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LeetCode 3922 - Minimum Flips to Make Binary String Coherent

LeetCode Problem 3922 Difficulty: 🟡 Medium Topics: String Solution Problem Understanding We are given a binary string s consisting only of '0' and '1' . A string is called coherent if it does not contain either of the following patterns as a subsequence: "011" "110" Recall that a subsequence does not need to occupy consecutive positions. We only need to be able to select characters in order. In one operation,...

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LeetCode 3924 - Minimum Threshold Path With Limited Heavy Edges

LeetCode Problem 3924 Difficulty: 🔴 Hard Topics: Binary Search, Breadth-First Search, Graph Theory Solution LeetCode 3924 - Minimum Threshold Path With Limited Heavy Edges Problem Understanding We are given an undirected weighted graph with n nodes and a list of weighted edges. We must travel from source to target . The key concept in this problem is the definition of a threshold . Once a threshold is chosen, every edge...

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LeetCode 3899 - Angles of a Triangle

LeetCode Problem 3899 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding We are given an array sides containing exactly three positive integers. Each integer represents the length of one side of a potential triangle. The task is to determine whether these three side lengths can form a triangle with positive area. A triangle exists if and only if the triangle inequality holds. For three sides a , b , and...

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LeetCode 3933 - Largest Local Values in a Matrix II

LeetCode Problem 3933 Difficulty: 🟡 Medium Topics: Array, Matrix, Prefix Sum Solution Problem Understanding The problem asks us to find local maximums in a 2D matrix according to a specialized neighborhood rule. Each cell in the matrix has a value x . A cell is a local maximum if it is non-zero and no neighboring cell within a distance of x in both row and column has a strictly greater...

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LeetCode 3926 - Count Valid Word Occurrences

LeetCode Problem 3926 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Counting Solution Problem Understanding The problem asks us to count occurrences of specific words in a string that is formed by concatenating an array of smaller string "chunks". The twist is that words are defined in a non-standard way: they can include joiner hyphens , which are hyphens that appear between two lowercase English letters. Any other character, including...

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LeetCode 3891 - Minimum Increase to Maximize Special Indices

LeetCode Problem 3891 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Greedy, Prefix Sum Solution Problem Understanding This problem asks us to modify an integer array to create as many special indices as possible, where a special index i is one where nums[i] > nums[i-1] and nums[i] > nums[i+1] . We can only increase values in the array, one unit at a time, and our goal is to maximize the number...

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LeetCode 3843 - First Element with Unique Frequency

LeetCode Problem 3843 Difficulty: 🟡 Medium Topics: Array, Hash Table, Counting Solution Correctness The proposed solution does not answer the question that Exercise 4.3.1.17 asks. The exercise is specific: given that $v_{n-1} \ge \lfloor b/2 \rfloor$ and $u_n = v_{n-1}$, one must show that the quotient digit $q$ in the division step satisfies $q = b-1$ or $q = b-2$. This is a statement about bounds on the first quotient...

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LeetCode 3687 - Library Late Fee Calculator

LeetCode Problem 3687 Difficulty: 🟢 Easy Topics: Array, Simulation Solution Problem Understanding The problem asks us to calculate the total late fee for a library based on how many days each book was returned late. You are given an integer array daysLate , where each element daysLate[i] represents the number of days the i-th book was returned past its due date. The penalty rules are tiered: if a book is...

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LeetCode 3672 - Sum of Weighted Modes in Subarrays

LeetCode Problem 3672 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sliding Window, Counting, Ordered Set Solution Problem Understanding The problem asks us to calculate the sum of weighted modes for all subarrays of length k in a given array nums . Each subarray is contiguous and has exactly k elements. For a subarray, the mode is the element that occurs most frequently. If multiple elements share the same highest frequency,...

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LeetCode 3753 - Total Waviness of Numbers in Range II

LeetCode Problem 3753 Difficulty: 🔴 Hard Topics: Math, Dynamic Programming Solution Problem Understanding The problem asks us to compute a cumulative score over all integers in an inclusive range [num1, num2] , where each individual number has a score called waviness . The waviness of a number is defined as the number of positions in its digit sequence that qualify as either a peak or a valley. A digit is...

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LeetCode 3761 - Minimum Absolute Distance Between Mirror Pairs

LeetCode Problem 3761 Difficulty: 🟡 Medium Topics: Array, Hash Table, Math Solution Correctness The proposed solution does not answer the question that Exercise 4.3.1.17 asks. The exercise is specific: given that $v_{n-1} \ge \lfloor b/2 \rfloor$ and $u_n = v_{n-1}$, one must show that the quotient digit $q$ in the division step satisfies $q = b-1$ or $q = b-2$. This is a statement about bounds on the first quotient...

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LeetCode 3666 - Minimum Operations to Equalize Binary String

LeetCode Problem 3666 Difficulty: 🔴 Hard Topics: Math, String, Breadth-First Search, Union-Find, Ordered Set Solution Problem Understanding The problem asks us to transform a binary string s consisting of characters '0' and '1' into a string where all characters are '1' . The allowed operation is flipping exactly k different indices in one move, turning '0' to '1' and '1' to '0' . The goal is to find the minimum...

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LeetCode 3656 - Determine if a Simple Graph Exists

LeetCode Problem 3656 Difficulty: 🟡 Medium Topics: Array, Binary Search, Graph Theory, Sorting, Prefix Sum Solution Correctness The proposed solution explains in detail how Algorithm S computes subtraction in radix $b$ and how the complement-based correction works when a final borrow occurs. However, the exercise asks specifically to show that if $u_n = v_{n-1}$, then $q = b - 1$ or $b - 2$ , where $q$ is presumably the...

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LeetCode 3650 - Minimum Cost Path with Edge Reversals

LeetCode Problem 3650 Difficulty: 🟡 Medium Topics: Graph Theory, Heap (Priority Queue), Shortest Path Solution LeetCode 3650 - Minimum Cost Path with Edge Reversals Problem Understanding We are given a directed weighted graph with n nodes and a list of directed edges. Each edge u → v has a traversal cost w . Normally, we may travel only along the original directed edges and pay the edge weight. However, every...

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LeetCode 3645 - Maximum Total from Optimal Activation Order

LeetCode Problem 3645 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Greedy, Sorting, Heap (Priority Queue) Solution Problem Understanding This problem involves determining the maximum total value achievable by activating elements in an array under a set of constraints. We are given two arrays, value and limit , both of length n . Each element starts inactive, and activating an element adds its corresponding value[i] to the total. However, activation is...

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LeetCode 3631 - Sort Threats by Severity and Exploitability

LeetCode Problem 3631 Difficulty: 🟡 Medium Topics: Array, Sorting Solution Problem Understanding The problem gives a list of threats, where each threat is represented as a triplet [IDi, sevi, expi] . Each threat has a unique identifier, a severity value, and an exploitability value. From these two attributes, a derived metric called score is defined as score = 2 × severity + exploitability . The task is to reorder the...

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LeetCode 3581 - Count Odd Letters from Number

LeetCode Problem 3581 Difficulty: 🟢 Easy Topics: Hash Table, String, Simulation, Counting Solution Solution Algorithm S performs digit-by-digit subtraction in radix $b$ without requiring knowledge of whether $(u_{n-1}\ldots u_0) b \ge (v {n-1}\ldots v_0) b$. It produces digits $w_0, w_1, \ldots, w {n-1}$ and a final borrow $k \in {0,-1}$, where $k=-1$ occurs if and only if $u < v$. Assume Algorithm S is executed without prior ordering of the...

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LeetCode 3575 - Maximum Good Subtree Score

LeetCode Problem 3575 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Tree, Depth-First Search, Bitmask Solution LeetCode 3575 - Maximum Good Subtree Score Problem Understanding We are given a rooted tree with n nodes. Node 0 is the root, and the tree structure is described by the parent array par , where par[i] is the parent of node i . Each node contains an integer value vals[i] . For...

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LeetCode 3576 - Transform Array to All Equal Elements

LeetCode Problem 3576 Difficulty: 🟡 Medium Topics: Array, Greedy Solution Problem Understanding The problem asks whether it is possible to transform an array of integers containing only 1 and -1 into an array where all elements are equal by performing at most k operations. Each operation consists of selecting an index i (from 0 to n-2 ) and multiplying both nums[i] and nums[i + 1] by -1 . The array...

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LeetCode 3473 - Sum of K Subarrays With Length at Least M

LeetCode Problem 3473 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Prefix Sum Solution Problem Understanding The problem gives an integer array nums , together with two integers k and m . We must choose exactly k non-overlapping subarrays, and every chosen subarray must have length at least m . Among all valid choices, we want the maximum possible total sum. A subarray is a contiguous segment of the array. Non-overlapping...

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LeetCode 3485 - Longest Common Prefix of K Strings After Removal

LeetCode Problem 3485 Difficulty: 🔴 Hard Topics: Array, String, Trie Solution Problem Understanding This problem asks us to calculate the longest common prefix (LCP) among any k strings from a list of strings, after removing each string in turn . Specifically, for each index i , we remove words[i] from the array, then find the longest prefix shared by any k remaining strings. The output is an array where each...

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LeetCode 3410 - Maximize Subarray Sum After Removing All Occurrences of One Element

LeetCode Problem 3410 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Segment Tree Solution Solution Algorithm S performs digit-by-digit subtraction in radix $b$ without requiring knowledge of whether $(u_{n-1}\ldots u_0) b \ge (v {n-1}\ldots v_0) b$. It produces digits $w_0, w_1, \ldots, w {n-1}$ and a final borrow $k \in {0,-1}$, where $k=-1$ occurs if and only if $u < v$. Assume Algorithm S is executed without prior ordering of the...

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LeetCode 3455 - Shortest Matching Substring

LeetCode Problem 3455 Difficulty: 🔴 Hard Topics: Two Pointers, String, Binary Search, String Matching Solution Problem Understanding The problem asks us to find the length of the shortest substring in a given string s that matches a pattern string p , where the pattern contains exactly two wildcard '*' characters . Each '*' matches any sequence of zero or more characters , which means it can represent nothing, a single...

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LeetCode 3943 - Number of Pairs After Increment

LeetCode Problem 3943 Difficulty: 🔴 Hard Topics: — Solution Problem Understanding The problem gives two integer arrays nums1 and nums2 and a list of queries. Each query is either an increment operation on a subarray of nums2 or a pair-counting operation that asks for the number of pairs (j, k) such that nums1[j] + nums2[k] equals a target value tot . The input arrays represent sequences of integers, with nums1...

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LeetCode 3942 - Minimum Operations to Sort a Permutation

LeetCode Problem 3942 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding The problem gives an array nums that is guaranteed to be a permutation of integers from 0 to n - 1 . The goal is to transform this array into the sorted order [0, 1, 2, ..., n - 1] using only two allowed operations: a left rotation by one position and a full reversal of the array. A...

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LeetCode 3940 - Limit Occurrences in Sorted Array

LeetCode Problem 3940 Difficulty: 🟢 Easy Topics: — Solution LeetCode 3940 - Limit Occurrences in Sorted Array Problem Understanding This problem gives us a sorted integer array nums and an integer k . Our goal is to produce a result where every distinct value appears no more than k times. Because the array is already sorted in non-decreasing order, all occurrences of the same value appear consecutively. This property is...

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LeetCode 3941 - Password Strength

LeetCode Problem 3941 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding The problem requires calculating the strength of a password based on its distinct characters. Each character type contributes differently to the strength: lowercase letters add 1 point, uppercase letters add 2 points, digits add 3 points, and special characters from "!@#$" add 5 points. Importantly, each character is counted only once , even if it appears multiple times in...

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LeetCode 3937 - Minimum Operations to Make Array Modulo Alternating I

LeetCode Problem 3937 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding The problem asks us to transform an array of integers, nums , into a modulo alternating array with the minimum number of operations , where each operation is either incrementing or decrementing an element by 1. A modulo alternating array is defined with respect to an integer k and two distinct residues x and y in the range [0,...

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LeetCode 3938 - Maximum Path Intersection Sum in a Grid

LeetCode Problem 3938 Difficulty: 🟡 Medium Topics: — Solution Here’s a fully detailed technical solution guide for LeetCode 3938, following your formatting and content requirements. Problem Understanding The problem provides an m x n integer grid and two players with distinct movement constraints. Player 1 starts at the top-left (0, 0) and moves only right or down to reach the bottom-right (m-1, n-1) . Player 2 starts at the bottom-left...

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LeetCode 3939 - Count Non Adjacent Subsets in a Rooted Tree

LeetCode Problem 3939 Difficulty: 🔴 Hard Topics: — Solution LeetCode 3939 - Count Non Adjacent Subsets in a Rooted Tree Problem Understanding We are given a rooted tree with n nodes. The tree is represented by the parent array, where parent[i] tells us the parent of node i . Node 0 is always the root because parent[0] = -1 . Each node also has a value stored in nums[i] ....

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LeetCode 3936 - Minimum Swaps to Move Zeros to End

LeetCode Problem 3936 Difficulty: 🟢 Easy Topics: — Solution LeetCode 3936 - Minimum Swaps to Move Zeros to End Problem Understanding The problem gives us an integer array nums containing values between 0 and 100 . We may perform an operation where we choose any two distinct indices and swap their values. Our goal is to move all zeros to the end of the array while using the minimum possible...

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LeetCode 3934 - Smallest Unique Subarray

LeetCode Problem 3934 Difficulty: 🔴 Hard Topics: Array, Hash Table, Binary Search, Rolling Hash, Suffix Array, Hash Function Solution Problem Understanding The problem asks us to find the smallest possible length of a contiguous subarray such that there exists at least one subarray of that length that appears exactly once in the entire array. In other words, for a fixed length L , we look at every subarray of size...

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LeetCode 3932 - Count K-th Roots in a Range

LeetCode Problem 3932 Difficulty: 🟡 Medium Topics: Math, Binary Search Solution Problem Understanding This problem asks us to count how many integers in a given range [l, r] are perfect kth powers , meaning each integer can be expressed as x^k for some integer x . In other words, given the lower bound l , the upper bound r , and an exponent k , we want to identify all...

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LeetCode 3931 - Check Adjacent Digit Differences

LeetCode Problem 3931 Difficulty: 🟢 Easy Topics: String Solution Problem Understanding The problem asks us to determine whether the absolute difference between every pair of adjacent digits in a given string s is at most 2. The input s is a string of digits, with a minimum length of 2 and a maximum of 100. Each character in the string is guaranteed to be a digit, so we do not...

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LeetCode 3928 - Minimum Cost to Buy Apples II

LeetCode Problem 3928 Difficulty: 🔴 Hard Topics: Array, Graph Theory, Heap (Priority Queue), Shortest Path Solution Problem Understanding The problem asks us to determine the minimum cost to purchase apples starting from each shop, taking into account two types of costs: the local price of apples at each shop and the transportation costs along roads connecting the shops. Each road has a base cost to traverse when empty and a...

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LeetCode 3927 - Minimize Array Sum Using Divisible Replacements

LeetCode Problem 3927 Difficulty: 🟡 Medium Topics: Array, Hash Table, Math, Greedy, Number Theory Solution Problem Understanding The problem gives an integer array nums and allows an operation that can reduce values under a divisibility condition. Specifically, you may choose two indices a and b such that nums[a] % nums[b] == 0 , and then replace nums[a] with nums[b] . The effect of this operation is that any number in...

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LeetCode 3925 - Concatenate Array With Reverse

LeetCode Problem 3925 Difficulty: 🟢 Easy Topics: Array, Simulation Solution Problem Understanding The problem asks us to construct a new array by concatenating an input array with its reversed version. Given an integer array nums of length n , we must return a new array ans of length 2 * n . The first n elements of ans are exactly the same as nums , preserving order. The next n...

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LeetCode 3904 - Smallest Stable Index II

LeetCode Problem 3904 Difficulty: 🟡 Medium Topics: Array, Prefix Sum Solution Problem Understanding The problem gives an integer array nums of length n and an integer k . For every index i , we split the array into two overlapping parts: The prefix nums[0..i] The suffix nums[i..n-1] For that index, we compute an instability score: $$\text{instability}(i)=\max(nums[0..i])-\min(nums[i..n-1])$$ An index is considered stable if this value is less than or equal to...

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LeetCode 3923 - Minimum Generations to Target Point

LeetCode Problem 3923 Difficulty: 🟡 Medium Topics: Array, Hash Table, Simulation Solution LeetCode 3923 - Minimum Generations to Target Point Problem Understanding This problem defines a process that repeatedly creates new 3D points from existing points. We begin with the given list points , which forms generation 0 . For every later generation, we consider all distinct points that have been created so far, including points from every previous generation....

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LeetCode 3921 - Score Validator

LeetCode Problem 3921 Difficulty: 🟢 Easy Topics: Array, String, Simulation Solution LeetCode 3921 - Score Validator Problem Understanding This problem asks us to simulate a simple scoring system while processing a sequence of event strings from left to right. We are given an array called events , where each element represents one event. Two variables are maintained throughout the simulation: score , initially 0 counter , initially 0 Each event...

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LeetCode 3920 - Maximize Fixed Points After Deletions

LeetCode Problem 3920 Difficulty: 🔴 Hard Topics: Array, Binary Search, Sorting Solution Problem Understanding The problem asks us to maximize the number of fixed points in an array after performing deletions. A fixed point is an index i such that nums[i] == i . We are allowed to delete any number of elements from the array, and after each deletion, all remaining elements shift left, which reassigns the indices starting...

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LeetCode 3919 - Minimum Cost to Move Between Indices

LeetCode Problem 3919 Difficulty: 🟡 Medium Topics: Array, Greedy, Prefix Sum Solution LeetCode 3919 - Minimum Cost to Move Between Indices Problem Understanding We are given a strictly increasing array nums . Each position represents an index in the array, and we want to move between indices as cheaply as possible. For every index x , a special neighbor called closest(x) is defined. Since the array is strictly increasing, each...

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LeetCode 3918 - Sum of Primes Between Number and Its Reverse

LeetCode Problem 3918 Difficulty: 🟡 Medium Topics: Math, Number Theory Solution LeetCode 3918 - Sum of Primes Between Number and Its Reverse Problem Understanding The problem gives us a single integer n . We first construct another integer r by reversing the digits of n . For example: If n = 13 , then r = 31 If n = 10 , then r = 1 If n = 120...

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LeetCode 3917 - Count Indices With Opposite Parity

LeetCode Problem 3917 Difficulty: 🟢 Easy Topics: Array Solution LeetCode 3917 - Count Indices With Opposite Parity Problem Understanding The problem gives us an integer array nums of length n . For every index i , we must determine how many indices to its right contain a number with the opposite parity. Parity refers to whether a number is even or odd: Even numbers have a remainder of 0 when...

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LeetCode 3914 - Minimum Operations to Make Array Non Decreasing

LeetCode Problem 3914 Difficulty: 🟡 Medium Topics: Array, Greedy Solution LeetCode 3914 - Minimum Operations to Make Array Non Decreasing Problem Understanding We are given an array nums . In a single operation, we choose any contiguous subarray and increase every element in that subarray by the same positive integer value x . The cost of an operation is exactly the chosen value x . If we perform multiple operations,...

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LeetCode 3915 - Maximum Sum of Alternating Subsequence With Distance at Least K

LeetCode Problem 3915 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Segment Tree Solution Correctness The solution does address the correct exercise and correctly identifies that the task is to generalize Algorithm S by handling the case when subtraction is performed without knowing which operand is larger. It correctly uses the standard TAOCP idea: if a final borrow remains, then the computed digit string represents a complement representation, and an additional...

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LeetCode 3913 - Sort Vowels by Frequency

LeetCode Problem 3913 Difficulty: 🟡 Medium Topics: String, Sorting, Counting Solution Problem Understanding The problem requires us to reorder the vowels in a given string s based on their frequency, while keeping all consonants in their original positions. Specifically, the vowels must appear in non-increasing order of frequency . If two vowels have the same frequency, the one that appeared first in the string should come first in the sorted...

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LeetCode 3912 - Valid Elements in an Array

LeetCode Problem 3912 Difficulty: 🟢 Easy Topics: Array Solution Correctness The solution does address the correct exercise and correctly identifies that the task is to generalize Algorithm S by handling the case when subtraction is performed without knowing which operand is larger. It correctly uses the standard TAOCP idea: if a final borrow remains, then the computed digit string represents a complement representation, and an additional correction step is needed...

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LeetCode 3911 - K-th Smallest Remaining Even Integer in Subarray Queries

LeetCode Problem 3911 Difficulty: 🔴 Hard Topics: Array, Binary Search Solution Problem Understanding The problem provides a strictly increasing integer array nums and a list of queries, each consisting of [li, ri, ki] . For each query, we consider the subarray nums[li..ri] and remove all elements of this subarray from the infinite sequence of positive even integers . The task is to determine the kith smallest number remaining in that...

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LeetCode 3909 - Compare Sums of Bitonic Parts

LeetCode Problem 3909 Difficulty: 🟡 Medium Topics: Array Solution Problem Understanding The problem gives us a bitonic array nums , meaning an array that first strictly increases to a single peak element and then strictly decreases. The task is to split this array into two overlapping parts: The ascending part , which includes all elements from the start of the array up to and including the peak. The descending part...

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LeetCode 3910 - Count Connected Subgraphs with Even Node Sum

LeetCode Problem 3910 Difficulty: 🔴 Hard Topics: Array, Bit Manipulation, Depth-First Search, Breadth-First Search, Union-Find, Graph Theory, Enumeration Solution Correctness The solution does address the correct exercise and correctly identifies that the task is to generalize Algorithm S by handling the case when subtraction is performed without knowing which operand is larger. It correctly uses the standard TAOCP idea: if a final borrow remains, then the computed digit string represents...

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LeetCode 3908 - Valid Digit Number

LeetCode Problem 3908 Difficulty: 🟢 Easy Topics: Math Solution Problem Understanding The problem is asking us to determine whether a given integer n is valid with respect to a digit x based on two conditions. First, n must contain at least one occurrence of the digit x . Second, n must not start with digit x . The input n is a non-negative integer up to 105 , and x...

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LeetCode 3906 - Count Good Integers on a Grid Path

LeetCode Problem 3906 Difficulty: 🔴 Hard Topics: Dynamic Programming Solution Correctness The solution does address the correct exercise and correctly identifies that the task is to generalize Algorithm S by handling the case when subtraction is performed without knowing which operand is larger. It correctly uses the standard TAOCP idea: if a final borrow remains, then the computed digit string represents a complement representation, and an additional correction step is...

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LeetCode 3905 - Multi Source Flood Fill

LeetCode Problem 3905 Difficulty: 🟡 Medium Topics: Array, Breadth-First Search, Matrix Solution Problem Understanding The problem asks us to simulate a multi-source flood fill on an n x m grid. Each element of the sources array represents a starting point with a specific color, and all other cells start uncolored, represented as 0. At each time step, the currently colored cells spread their color to their four immediate neighbors (up,...

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LeetCode 3901 - Good Subsequence Queries

LeetCode Problem 3901 Difficulty: 🔴 Hard Topics: — Solution Correctness The solution does address the correct exercise and correctly identifies that the task is to generalize Algorithm S by handling the case when subtraction is performed without knowing which operand is larger. It correctly uses the standard TAOCP idea: if a final borrow remains, then the computed digit string represents a complement representation, and an additional correction step is needed...

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LeetCode 3903 - Smallest Stable Index I

LeetCode Problem 3903 Difficulty: 🟢 Easy Topics: Array, Prefix Sum Solution Problem Understanding The problem asks us to find the smallest index i in an integer array nums such that the instability score at that index is less than or equal to a given integer k . The instability score is defined as the difference between the maximum of the prefix nums[0..i] and the minimum of the suffix nums[i..n-1] ....

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LeetCode 3900 - Longest Balanced Substring After One Swap

LeetCode Problem 3900 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding We are given a binary string s containing only '0' and '1' . A substring is considered balanced when it contains exactly the same number of zeros and ones. Before choosing the substring, we are allowed to perform at most one swap between any two positions in the entire string. The swap is optional, so we may also choose...

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LeetCode 3898 - Find the Degree of Each Vertex

LeetCode Problem 3898 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding The problem asks us to calculate the degree of each vertex in an undirected graph represented by an adjacency matrix. The input is a 2D integer array matrix of size n x n , where matrix[i][j] = 1 indicates an edge between vertices i and j , and matrix[i][j] = 0 indicates no edge. Because the graph is undirected,...

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LeetCode 3897 - Maximum Value of Concatenated Binary Segments

LeetCode Problem 3897 Difficulty: 🔴 Hard Topics: — Solution Problem Understanding The problem presents two integer arrays nums1 and nums0 , each of size n . Each index i represents a binary segment consisting of a number of '1' bits followed by a number of '0' bits. Specifically, nums1[i] gives the count of consecutive '1' s and nums0[i] gives the count of consecutive '0' s in the segment. The task...

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LeetCode 3895 - Count Digit Appearances

LeetCode Problem 3895 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding The problem asks us to count how many times a specific decimal digit appears when writing out every number in the array. We are given an integer array nums and a single digit between 0 and 9 . For each number in the array, we inspect its decimal representation and count how many positions contain the target digit. The...

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LeetCode 3894 - Traffic Signal Color

LeetCode Problem 3894 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding This problem asks us to determine the current state of a traffic signal based on an integer timer that represents the remaining seconds for the signal. The rules for the signal are strictly defined: if the timer is 0 , the signal shows "Green" ; if it is exactly 30 , the signal shows "Orange" ; if it is...

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LeetCode 3896 - Minimum Operations to Transform Array into Alternating Prime

LeetCode Problem 3896 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding The problem asks us to transform an integer array nums into an alternating prime array , where numbers at even indices are prime and numbers at odd indices are non-prime. We are allowed to increment any number by 1 in one operation, and the goal is to minimize the total number of operations required. The input is an array...

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LeetCode 3892 - Minimum Operations to Achieve At Least K Peaks

LeetCode Problem 3892 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming Solution LeetCode 3892 - Minimum Operations to Achieve At Least K Peaks Problem Understanding We are given a circular array nums . An index is considered a peak if its value is strictly greater than both of its neighbors. Because the array is circular, the first and last elements are adjacent. For example, the neighbors of index 0 are nums[n...

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LeetCode 3887 - Incremental Even-Weighted Cycle Queries

LeetCode Problem 3887 Difficulty: 🔴 Hard Topics: Union-Find, Graph Theory Solution Problem Understanding This problem describes a dynamic process of building an undirected graph with weighted edges where the weights are binary, either 0 or 1. You start with n isolated nodes labeled from 0 to n-1 . You are given a list of potential edges with weights, and you must add each edge in the given order only if...

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LeetCode 3886 - Sum of Sortable Integers

LeetCode Problem 3886 Difficulty: 🔴 Hard Topics: Array, Math, Sorting, Enumeration Solution Problem Understanding The problem asks us to find all integers k that divide the length of the input array nums and for which the array can be sorted into non-decreasing order using a very specific operation. The operation is to partition nums into consecutive subarrays of length k and then cyclically rotate each subarray independently any number of...

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LeetCode 3849 - Maximum Bitwise XOR After Rearrangement

LeetCode Problem 3849 Difficulty: 🟡 Medium Topics: String, Greedy, Bit Manipulation Solution Corrected Solution for Exercise 4.3.1.9 Exercise 4.3.1.9 asks for a generalization of Algorithm A to add two $n$-place numbers in a mixed-radix system with bases $b_0, b_1, \dots, b_{n-1}$ from right to left. Algorithm A in TAOCP §4.3.1 describes standard addition with carry propagation in a single-radix positional system. Here we adapt it to mixed-radix arithmetic, where each...

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LeetCode 3874 - Valid Subarrays With Exactly One Peak

LeetCode Problem 3874 Difficulty: 🟡 Medium Topics: Array, Math Solution Problem Understanding The problem asks us to count the number of contiguous subarrays of a given integer array nums that contain exactly one peak , where a peak is defined as an element nums[i] that is strictly greater than both its immediate neighbors nums[i-1] and nums[i+1] . Furthermore, for a subarray to be valid, the distance from the peak to...

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LeetCode 3861 - Minimum Capacity Box

LeetCode Problem 3861 Difficulty: 🟢 Easy Topics: Array Solution Problem Understanding The problem presents a straightforward search scenario. You are given an array capacity where each element represents the storage capacity of a box. You are also given an integer itemSize , representing the size of an item you want to store. The task is to find the index of the box that has the smallest capacity that is still...

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LeetCode 3859 - Count Subarrays With K Distinct Integers

LeetCode Problem 3859 Difficulty: 🔴 Hard Topics: Array, Hash Table, Sliding Window, Counting Solution Problem Understanding This problem asks us to count subarrays of a given integer array nums such that each subarray contains exactly k distinct integers , and each distinct integer in the subarray appears at least m times . In other words, for a subarray to be valid, it must satisfy two constraints: a cardinality constraint (exactly...

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LeetCode 3824 - Minimum K to Reduce Array Within Limit

LeetCode Problem 3824 Difficulty: 🟡 Medium Topics: Array, Binary Search Solution Problem Understanding This problem asks us to determine the minimum positive integer k such that, after repeatedly subtracting k from each element of the array nums , the total number of operations needed to reduce every element to non-positive is at most k^2 . In other words, for each element nums[i] , the number of operations required is ceil(nums[i]...

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LeetCode 3820 - Pythagorean Distance Nodes in a Tree

LeetCode Problem 3820 Difficulty: 🟡 Medium Topics: Tree, Breadth-First Search Solution Problem Understanding The problem requires identifying special nodes in a tree based on distances to three distinct target nodes, x , y , and z . A node is special if the distances from it to x , y , and z form a Pythagorean triplet , meaning that when sorted in ascending order, the sum of squares of...

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LeetCode 3831 - Median of a Binary Search Tree Level

LeetCode Problem 3831 Difficulty: 🟡 Medium Topics: Tree, Depth-First Search, Breadth-First Search, Binary Search Tree, Binary Tree Solution Corrected Solution for Exercise 4.3.1.9 Exercise 4.3.1.9 asks for a generalization of Algorithm A to add two $n$-place numbers in a mixed-radix system with bases $b_0, b_1, \dots, b_{n-1}$ from right to left. Algorithm A in TAOCP §4.3.1 describes standard addition with carry propagation in a single-radix positional system. Here we adapt...

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LeetCode 3810 - Minimum Operations to Reach Target Array

LeetCode Problem 3810 Difficulty: 🟡 Medium Topics: Array, Hash Table, Greedy Solution Problem Understanding We are given two arrays, nums and target , of equal length. The array nums represents the current state, while target represents the desired final state. In one operation, we choose a value x . Then we locate every maximal contiguous segment whose current value is exactly x . Every position inside those segments is simultaneously...

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LeetCode 3814 - Maximum Capacity Within Budget

LeetCode Problem 3814 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Binary Search, Sorting Solution Corrected Solution for Exercise 4.3.1.9 Exercise 4.3.1.9 asks for a generalization of Algorithm A to add two $n$-place numbers in a mixed-radix system with bases $b_0, b_1, \dots, b_{n-1}$ from right to left. Algorithm A in TAOCP §4.3.1 describes standard addition with carry propagation in a single-radix positional system. Here we adapt it to mixed-radix arithmetic,...

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LeetCode 3809 - Best Reachable Tower

LeetCode Problem 3809 Difficulty: 🟡 Medium Topics: Array Solution Problem Understanding This problem asks us to identify the "best reachable tower" from a given center location within a specified Manhattan distance radius. Each tower has a coordinate (xi, yi) and a quality factor qi . A tower is considered reachable if its Manhattan distance from the center (cx, cy) is less than or equal to the given radius . Among...

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LeetCode 3797 - Count Routes to Climb a Rectangular Grid

LeetCode Problem 3797 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Matrix, Prefix Sum Solution LeetCode 3797 - Count Routes to Climb a Rectangular Grid Problem Understanding We are given an n × m grid where each cell is either available ( '.' ) or blocked ( '#' ). A route starts from any available cell in the bottom row and must eventually end in the top row. During the route,...

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LeetCode 3800 - Minimum Cost to Make Two Binary Strings Equal

LeetCode Problem 3800 Difficulty: 🟡 Medium Topics: String, Greedy Solution Corrected Solution for Exercise 4.3.1.9 Exercise 4.3.1.9 asks for a generalization of Algorithm A to add two $n$-place numbers in a mixed-radix system with bases $b_0, b_1, \dots, b_{n-1}$ from right to left. Algorithm A in TAOCP §4.3.1 describes standard addition with carry propagation in a single-radix positional system. Here we adapt it to mixed-radix arithmetic, where each digit position...

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LeetCode 3796 - Find Maximum Value in a Constrained Sequence

LeetCode Problem 3796 Difficulty: 🟡 Medium Topics: Array, Greedy Solution Corrected Solution to Exercise 4.3.1.6 We are asked to design an algorithm that adds two numbers digit by digit from most significant to least significant , producing each output digit only when it cannot possibly be affected by future carries. Once an output digit is committed, it may never be revised. We must maintain linear time complexity in the number...

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LeetCode 3798 - Largest Even Number

LeetCode Problem 3798 Difficulty: 🟢 Easy Topics: String Solution LeetCode 3798 - Largest Even Number Problem Understanding We are given a string s that contains only the characters '1' and '2' . We are allowed to delete any number of characters while preserving the relative order of the remaining characters. In other words, we may choose any subsequence of the original string. The goal is to produce the largest possible...

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LeetCode 3793 - Find Users with High Token Usage

LeetCode Problem 3793 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding The prompts table records every prompt submitted by a user to an AI system. Each row contains a user_id , the prompt text itself, and the number of tokens consumed by that prompt. The task is to analyze prompt usage on a per-user basis and return only users who satisfy two separate conditions. First, the user must have submitted...

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LeetCode 3787 - Find Diameter Endpoints of a Tree

LeetCode Problem 3787 Difficulty: 🟡 Medium Topics: Tree, Breadth-First Search, Graph Theory Solution Problem Understanding The problem asks us to identify special nodes in a tree, which are nodes that serve as endpoints of any diameter path . A tree is an acyclic connected graph, and its diameter is defined as the longest simple path between any two nodes. Multiple diameter paths can exist, especially in trees with branches of...

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LeetCode 3785 - Minimum Swaps to Avoid Forbidden Values

LeetCode Problem 3785 Difficulty: 🔴 Hard Topics: Array, Hash Table, Greedy, Counting Solution Problem Understanding This problem asks us to modify an array nums so that for every index i , the element at nums[i] is not equal to the corresponding element at forbidden[i] . The only allowed operation is swapping any two distinct elements of nums . Our goal is to determine the minimum number of swaps required to...

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LeetCode 3777 - Minimum Deletions to Make Alternating Substring

LeetCode Problem 3777 Difficulty: 🔴 Hard Topics: String, Segment Tree Solution Problem Understanding We are given a mutable binary string consisting only of 'A' and 'B' . There are two kinds of queries: [1, j] flips the character at position j . If it was 'A' , it becomes 'B' , and vice versa. This permanently changes the string and affects all future queries. [2, l, r] asks for the...

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LeetCode 3783 - Mirror Distance of an Integer

LeetCode Problem 3783 Difficulty: 🟢 Easy Topics: Math Solution LeetCode 3783 - Mirror Distance of an Integer Problem Understanding The problem gives us a positive integer n and asks us to compute its mirror distance . The mirror distance is defined as: $$|n - reverse(n)|$$ where reverse(n) is the integer obtained by reversing the decimal digits of n , and |x| denotes the absolute value. For example, if n =...

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LeetCode 3776 - Minimum Moves to Balance Circular Array

LeetCode Problem 3776 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting Solution Corrected Solution for Exercise 4.3.1.7 Exercise 4.3.1.7 asks for the average number of times the algorithm of Exercise 5 finds that a carry propagates through exactly $k$ digits of the partial answer, for $k = 1, 2, \dots, n$, under the assumption that both inputs are independent and uniformly distributed integers in $[0, b^n - 1]$. We provide a...

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LeetCode 3752 - Lexicographically Smallest Negated Permutation that Sums to Target

LeetCode Problem 3752 Difficulty: 🟡 Medium Topics: Array, Math, Two Pointers, Greedy, Sorting Solution LeetCode 3752: Lexicographically Smallest Negated Permutation that Sums to Target Problem Understanding We are given two values: n , which determines the numbers 1, 2, ..., n target , which is the required sum of the final array We must construct an array of length n whose absolute values are exactly the numbers 1 through n...

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LeetCode 3747 - Count Distinct Integers After Removing Zeros

LeetCode Problem 3747 Difficulty: 🟡 Medium Topics: Math, Dynamic Programming Solution Problem Understanding The problem asks us to consider all integers from 1 up to a given number n . For each integer, we are required to write down a transformed version of that number in which all zeros are removed . For example, 102 would become 12 , and 500 would become 5 . After performing this transformation for...

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LeetCode 3740 - Minimum Distance Between Three Equal Elements I

LeetCode Problem 3740 Difficulty: 🟢 Easy Topics: Array, Hash Table Solution LeetCode 3740 - Minimum Distance Between Three Equal Elements I Problem Understanding The problem gives us an integer array nums and asks us to find three distinct indices (i, j, k) such that all three positions contain the same value: nums[i] == nums[j] == nums[k] Such a triple is called a good tuple. For every good tuple, we compute...

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LeetCode 3735 - Lexicographically Smallest String After Reverse II

LeetCode Problem 3735 Difficulty: 🔴 Hard Topics: String, Binary Search, Rolling Hash, Suffix Array, Hash Function Solution Problem Understanding The problem is asking us to manipulate a string s of length n in order to produce the lexicographically smallest possible string after exactly one operation. The operation allows you to choose an integer k between 1 and n and either reverse the first k characters or reverse the last k...

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LeetCode 3732 - Maximum Product of Three Elements After One Replacement

LeetCode Problem 3732 Difficulty: 🟡 Medium Topics: Array, Math, Greedy, Sorting Solution Problem Understanding This problem asks us to maximize the product of any three distinct elements in an array, given that we are allowed to replace exactly one element in the array with any integer from -10^5 to 10^5 . The input is an integer array nums of length at least 3 and at most 10^5 . The goal...

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LeetCode 3719 - Longest Balanced Subarray I

LeetCode Problem 3719 Difficulty: 🟡 Medium Topics: Array, Hash Table, Divide and Conquer, Segment Tree, Prefix Sum Solution Problem Understanding The problem asks us to find the longest contiguous subarray of an integer array nums such that the number of distinct even numbers in the subarray is equal to the number of distinct odd numbers . In simpler terms, a subarray is "balanced" if it has an equal count of...

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LeetCode 3713 - Longest Balanced Substring I

LeetCode Problem 3713 Difficulty: 🟡 Medium Topics: Hash Table, String, Counting, Enumeration Solution Problem Understanding The problem is asking us to find the length of the longest substring of a given string s where all distinct characters in that substring appear the same number of times. In other words, for any candidate substring, if you count how many times each unique character appears, all counts must be identical. The input...

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LeetCode 3701 - Compute Alternating Sum

LeetCode Problem 3701 Difficulty: 🟢 Easy Topics: Array, Simulation Solution Problem Understanding This problem asks us to compute the alternating sum of an integer array nums . The alternating sum is calculated by taking the sum of elements at even indices (0, 2, 4, ...) and subtracting the sum of elements at odd indices (1, 3, 5, ...). For example, given nums = [1, 3, 5, 7] , we compute...

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LeetCode 3678 - Smallest Absent Positive Greater Than Average

LeetCode Problem 3678 Difficulty: 🟢 Easy Topics: Array, Hash Table Solution The crash is now purely an input-format mismatch, and it already reveals exactly where the implementation diverges from the actual problem. What the traceback tells us The program fails here: n, m = map(int, input().split()) with: ValueError: not enough values to unpack (expected 2, got 1) So the input line is: 5 4 1 2 3 1 This means:...

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LeetCode 3673 - Find Zombie Sessions

LeetCode Problem 3673 Difficulty: 🔴 Hard Topics: — Solution Corrected Solution for Exercise 4.3.1.7 Exercise 4.3.1.7 asks for the average number of times the algorithm of Exercise 5 finds that a carry propagates through exactly $k$ digits of the partial answer, for $k = 1, 2, \dots, n$, under the assumption that both inputs are independent and uniformly distributed integers in $[0, b^n - 1]$. We provide a careful probabilistic...

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LeetCode 3670 - Maximum Product of Two Integers With No Common Bits

LeetCode Problem 3670 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Bit Manipulation Solution Problem Understanding The problem asks us to find the maximum product of two distinct elements in an array of integers, under the constraint that their binary representations do not share any set bits. In other words, for any two numbers nums[i] and nums[j] that we consider, the bitwise AND of the two numbers must be zero (...

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LeetCode 3669 - Balanced K-Factor Decomposition

LeetCode Problem 3669 Difficulty: 🟡 Medium Topics: Math, Backtracking, Number Theory Solution Problem Understanding The problem asks us to split a positive integer n into exactly k positive integers such that the product of these integers equals n . Among all possible splits, we are required to find one in which the maximum difference between any two numbers is minimized . In simpler terms, we want to factorize n into...

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LeetCode 3659 - Partition Array Into K-Distinct Groups

LeetCode Problem 3659 Difficulty: 🟡 Medium Topics: Array, Hash Table, Counting Solution LeetCode 3659 - Partition Array Into K-Distinct Groups Problem Understanding We are given an integer array nums and an integer k . The goal is to determine whether all elements of the array can be partitioned into one or more groups such that every group satisfies two conditions: Each group contains exactly k elements. All elements within a...

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LeetCode 3649 - Number of Perfect Pairs

LeetCode Problem 3649 Difficulty: 🟡 Medium Topics: Array, Math, Two Pointers, Sorting Solution Problem Understanding This problem asks us to count the number of perfect pairs in an integer array nums . A pair (i, j) is perfect if i < j and the elements at these indices satisfy two conditions: the minimum of |a - b| and |a + b| is less than or equal to the smaller absolute...

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LeetCode 3637 - Trionic Array I

LeetCode Problem 3637 Difficulty: 🟢 Easy Topics: Array Solution Solution We interpret the task as follows. Two nonnegative integers are given in radix $b$, each represented as a sequence of digits. The digits are not processed in the standard right-to-left carry propagation. Instead, output digits must be produced strictly from most significant to least significant position, and once a digit is output it may never be revised. Carries generated by...

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LeetCode 3644 - Maximum K to Sort a Permutation

LeetCode Problem 3644 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation Solution Problem Understanding The problem provides a permutation array nums of length n , meaning it contains each integer from 0 to n-1 exactly once, in some arbitrary order. The task is to determine the maximum value of k such that the array can be sorted in non-decreasing order using only swaps where the bitwise AND of the two numbers...

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LeetCode 3628 - Maximum Number of Subsequences After One Inserting

LeetCode Problem 3628 Difficulty: 🟡 Medium Topics: String, Dynamic Programming, Greedy, Prefix Sum Solution Correctness The solution partially addresses the exercise, but it does not fully satisfy what was asked. The exercise is not asking for modern algorithms that resemble the work of Sun Tsï, al-Khwārizmī, al-Uqlidisī, Fibonacci, and Recorde. It asks the reader to study the historical writings and translate their methods as faithfully as possible into precise algorithmic...

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LeetCode 3624 - Number of Integers With Popcount-Depth Equal to K II

LeetCode Problem 3624 Difficulty: 🔴 Hard Topics: Array, Divide and Conquer, Binary Indexed Tree, Segment Tree Solution Problem Understanding The problem asks us to efficiently handle queries on an array nums involving a special property called the popcount-depth . The popcount-depth of a number x is defined as the number of times we repeatedly apply the binary population count (the number of 1 bits in x ) until we reach...

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LeetCode 3627 - Maximum Median Sum of Subsequences of Size 3

LeetCode Problem 3627 Difficulty: 🟡 Medium Topics: Array, Math, Greedy, Sorting, Game Theory Solution LeetCode 3627 - Maximum Median Sum of Subsequences of Size 3 Problem Understanding We are given an array nums whose length is always divisible by 3 . The array must be emptied by repeatedly selecting exactly three elements. For each selected triple, we compute its median, add that median to our answer, and remove all three...

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LeetCode 3629 - Minimum Jumps to Reach End via Prime Teleportation

LeetCode Problem 3629 Difficulty: 🟡 Medium Topics: Array, Hash Table, Math, Breadth-First Search, Number Theory Solution Problem Understanding This problem is essentially about navigating an array using two types of moves: adjacent steps and prime-based teleportation . You start at the first index and want to reach the last index in the minimum number of moves. An adjacent step is straightforward: you can move to the next or previous index...

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LeetCode 3603 - Minimum Cost Path with Alternating Directions II

LeetCode Problem 3603 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Matrix Solution Correctness No. The proposed solution does not answer Exercise 4.3.1.1 at all. Exercise 4.3.1.1 asks the reader to study the early history of classical arithmetic algorithms by consulting historical sources (e.g., Sun Tzu, Muhammad ibn Musa al-Khwarizmi, Abu al-Hasan al-Uqlidisi, Fibonacci, and Robert Recorde) and to translate their arithmetic methods into precise algorithmic notation. The proposed solution discusses...

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LeetCode 3623 - Count Number of Trapezoids I

LeetCode Problem 3623 Difficulty: 🟡 Medium Topics: Array, Hash Table, Math, Geometry Solution Problem Understanding The problem asks us to count the number of horizontal trapezoids that can be formed from a set of points in 2D Cartesian space. A horizontal trapezoid is defined as a convex quadrilateral that has at least one pair of horizontal sides , meaning two sides are parallel to the x-axis. Since two sides are...

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LeetCode 3613 - Minimize Maximum Component Cost

LeetCode Problem 3613 Difficulty: 🟡 Medium Topics: Binary Search, Union-Find, Graph Theory, Sorting Solution Problem Understanding The problem asks us to minimize the maximum cost among components in a connected undirected graph after removing edges. Each edge has a weight, and the cost of a connected component is the largest weight of any edge in that component. You can remove edges freely, but the graph must end up with at...

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LeetCode 3608 - Minimum Time for K Connected Components

LeetCode Problem 3608 Difficulty: 🟡 Medium Topics: Binary Search, Union-Find, Graph Theory, Sorting Solution LeetCode 3608 - Minimum Time for K Connected Components Problem Understanding We are given an undirected graph with n vertices and a list of edges. Each edge has a removal time timei . The graph evolves over time. At time t , every edge whose removal time satisfies timei <= t has already been removed. All...

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LeetCode 3601 - Find Drivers with Improved Fuel Efficiency

LeetCode Problem 3601 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem asks us to analyze fuel efficiency trends for drivers across two different periods of the year. We are given two tables: drivers , which stores each driver's identifier and name. trips , which stores individual trip records, including distance traveled and fuel consumed. For every trip, fuel efficiency is defined as: $$\text{fuel efficiency} = \frac{\text{distance_km}}{\text{fuel_consumed}}$$ The year...

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LeetCode 3602 - Hexadecimal and Hexatrigesimal Conversion

LeetCode Problem 3602 Difficulty: 🟢 Easy Topics: Math, String Solution LeetCode 3602 - Hexadecimal and Hexatrigesimal Conversion Problem Understanding The problem gives us a single integer n and asks us to construct a string from two different number system conversions. First, we compute n² and convert that value into its hexadecimal (base-16) representation using the characters: 0-9 for values 0 through 9 A-F for values 10 through 15 Next, we...

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LeetCode 3584 - Maximum Product of First and Last Elements of a Subsequence

LeetCode Problem 3584 Difficulty: 🟡 Medium Topics: Array, Two Pointers Solution Analysis of Program B and Register X Program B is designed to perform a sequence of numerical calculations using the X-register of a hypothetical or HP-style RPN calculator. In such machines, the X-register holds the current number on the stack. If the program does not explicitly store or overwrite the contents of X, leftover or "garbage" values from prior...

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LeetCode 3598 - Longest Common Prefix Between Adjacent Strings After Removals

LeetCode Problem 3598 Difficulty: 🟡 Medium Topics: Array, String Solution Problem Understanding We are given a token placed at position $n$ on a vertical line of cells labeled from $1$ at the top to $n$ at the bottom. The goal is to count how many distinct sequences of moves can bring the token from $n$ down to $1$. From a position $x > 1$, two types of moves are allowed....

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LeetCode 3587 - Minimum Adjacent Swaps to Alternate Parity

LeetCode Problem 3587 Difficulty: 🟡 Medium Topics: Array, Greedy Solution Problem Understanding The problem requires transforming a given array of distinct integers into an arrangement where the parity of adjacent elements alternates - that is, an even number must always be next to an odd number, and vice versa. The only allowed operation is swapping adjacent elements , and we need to compute the minimum number of such swaps required...

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LeetCode 3583 - Count Special Triplets

LeetCode Problem 3583 Difficulty: 🟡 Medium Topics: Array, Hash Table, Counting Solution Problem Understanding This problem asks us to count the number of special triplets in an integer array nums . A special triplet (i, j, k) must satisfy three conditions: the indices are strictly increasing 0 <= i < j < k < n , nums[i] is exactly double nums[j] , and nums[k] is also exactly double nums[j] ....

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LeetCode 3562 - Maximum Profit from Trading Stocks with Discounts

LeetCode Problem 3562 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Tree, Depth-First Search Solution Problem Understanding This problem asks us to maximize profit from buying and selling stocks under a hierarchical discount structure. Each employee can buy a stock today at a present price and sell it tomorrow at a future price. The company hierarchy forms a tree, where employee 1 is the CEO and the direct or indirect boss...

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LeetCode 3569 - Maximize Count of Distinct Primes After Split

LeetCode Problem 3569 Difficulty: 🔴 Hard Topics: Array, Math, Segment Tree, Number Theory Solution Here is a complete, detailed technical solution guide following your exact formatting rules. Problem Understanding This problem asks us to handle dynamic array updates and, after each update, find the maximum sum of distinct prime counts across any valid split of the array. Formally, we are given an integer array nums of length n and a...

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LeetCode 3551 - Minimum Swaps to Sort by Digit Sum

LeetCode Problem 3551 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sorting Solution Problem Understanding The problem asks us to sort an array of distinct positive integers not by their natural numeric value, but by the sum of their digits . If two numbers share the same digit sum, the smaller number must come first. After determining this sorted order, we must calculate the minimum number of swaps needed to transform...

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LeetCode 3568 - Minimum Moves to Clean the Classroom

LeetCode Problem 3568 Difficulty: 🟡 Medium Topics: Array, Hash Table, Bit Manipulation, Breadth-First Search, Matrix Solution LeetCode 3568 - Minimum Moves to Clean the Classroom Problem Understanding We are given a grid representing a classroom. A student starts at the cell marked 'S' and must collect every litter cell marked 'L' . Movement is allowed only in the four cardinal directions, and moving one cell costs exactly one unit of...

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LeetCode 3564 - Seasonal Sales Analysis

LeetCode Problem 3564 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem asks us to analyze sales data and determine the most popular product category for each season based on the total quantity sold. The input consists of two tables: sales , which records individual transactions including product ID, date, quantity, and price; and products , which maps each product ID to its name and category. The expected output...

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LeetCode 3539 - Find Sum of Array Product of Magical Sequences

LeetCode Problem 3539 Difficulty: 🔴 Hard Topics: Array, Math, Dynamic Programming, Bit Manipulation, Combinatorics, Bitmask Solution Problem Understanding The expression in the statement should be interpreted as: $$2^{seq[0]} + 2^{seq[1]} + \cdots + 2^{seq[m-1]}$$ A sequence seq of length m is magical when the binary representation of this sum contains exactly k set bits. Each element of the sequence is an index into nums . The contribution of an index...

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LeetCode 3555 - Smallest Subarray to Sort in Every Sliding Window

LeetCode Problem 3555 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Stack, Greedy, Sorting, Monotonic Stack Solution Problem Understanding We are given an array nums and a window size k . For every contiguous subarray of length k , we must determine the minimum length of a continuous segment that needs to be sorted so that the entire window becomes non-decreasing. In other words, for each sliding window: nums[i : i...

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LeetCode 3550 - Smallest Index With Digit Sum Equal to Index

LeetCode Problem 3550 Difficulty: 🟢 Easy Topics: Array, Math Solution Problem Understanding This problem asks us to find the smallest index i in an integer array nums such that the sum of the digits of nums[i] equals i . In other words, for each element in the array, we compute the sum of its digits and check whether that sum matches the element's index. If multiple indices satisfy this condition,...

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LeetCode 3548 - Equal Sum Grid Partition II

LeetCode Problem 3548 Difficulty: 🔴 Hard Topics: Array, Hash Table, Matrix, Enumeration, Prefix Sum Solution Problem Understanding The problem is asking whether a given m x n matrix of positive integers can be split exactly once , either horizontally or vertically, such that the sums of the two resulting sections are equal, or can be made equal by discounting at most one cell . The catch is that if you...

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LeetCode 3531 - Count Covered Buildings

LeetCode Problem 3531 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sorting Solution Solution A single-precision floating point number in MIX, as defined in Section 4.2.1, consists of a sign byte, an exponent field, and a normalized fraction stored in one word. A double-precision floating point number in format (1) consists of the same sign and exponent structure, but with an eight-byte fraction split across two words, the most significant five...

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LeetCode 3537 - Fill a Special Grid

LeetCode Problem 3537 Difficulty: 🟡 Medium Topics: Array, Divide and Conquer, Matrix Solution Problem Understanding The problem asks us to generate a special 2ⁿ x 2ⁿ grid filled with integers from 0 to 4ⁿ - 1 (note that 22n - 1 in the problem is likely a typo; it should be 4^n - 1 ) such that certain order constraints between quadrants are satisfied. Specifically, the grid is divided recursively...

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LeetCode 3526 - Range XOR Queries with Subarray Reversals

LeetCode Problem 3526 Difficulty: 🔴 Hard Topics: Array, Tree, Binary Tree Solution Here’s a full technical solution guide for LeetCode 3526 - Range XOR Queries with Subarray Reversals following your requested structure and formatting: Problem Understanding The problem provides an array nums of integers and a list of queries , where each query can either update a value in the array, reverse a subarray, or compute the XOR of a...

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LeetCode 3522 - Calculate Score After Performing Instructions

LeetCode Problem 3522 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Simulation Solution Problem Understanding This problem asks you to simulate a linear sequence of instructions that can either modify a running score or move the instruction pointer by a specified offset. You are given two arrays, instructions and values , both of size n . Each index i represents an instruction. If instructions[i] is "add" , you add values[i]...

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LeetCode 3520 - Minimum Threshold for Inversion Pairs Count

LeetCode Problem 3520 Difficulty: 🟡 Medium Topics: Array, Binary Search, Binary Indexed Tree, Segment Tree Solution Solution Program M computes a double-precision product by expanding each normalized operand into high and low halves, forming four partial products, then discarding all terms that lie strictly to the right of the retained word boundary. The only arithmetic operations that combine values are additions of aligned partial results inside fixed byte fields. Overflow...

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LeetCode 3502 - Minimum Cost to Reach Every Position

LeetCode Problem 3502 Difficulty: 🟢 Easy Topics: Array Solution Problem Understanding You are given an array cost where cost[i] represents how much person i charges if you want to swap places with them while they are in front of you. Initially, you stand at position n , which is the very end of a line containing positions 0 through n . Your goal is to determine the minimum cost required...

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LeetCode 3495 - Minimum Operations to Make Array Elements Zero

LeetCode Problem 3495 Difficulty: 🔴 Hard Topics: Array, Math, Bit Manipulation Solution Problem Understanding This problem asks us to determine the minimum number of operations required to reduce all elements of arrays defined by queries to zero, where each query [l, r] defines an array of consecutive integers from l to r . The allowed operation consists of selecting any two elements a and b from the array and replacing...

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LeetCode 3487 - Maximum Unique Subarray Sum After Deletion

LeetCode Problem 3487 Difficulty: 🟢 Easy Topics: Array, Hash Table, Greedy Solution Problem Understanding The problem asks us to find the maximum sum of a subarray from an integer array nums under two key constraints: all elements in the chosen subarray must be unique, and we are allowed to delete any number of elements (except leaving the array empty) before selecting the subarray. In other words, we are looking for...

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LeetCode 3466 - Maximum Coin Collection

LeetCode Problem 3466 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding The problem describes Mario driving along a two-lane freeway with coins (or tolls) on each mile. The arrays lane1 and lane2 represent the coin values at each mile for each lane. Positive numbers mean Mario collects coins, negative numbers mean Mario loses coins. Mario always starts in lane 1 but can switch lanes up to two times...

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LeetCode 3483 - Unique 3-Digit Even Numbers

LeetCode Problem 3483 Difficulty: 🟢 Easy Topics: Array, Hash Table, Recursion, Enumeration Solution Here’s a comprehensive technical guide for LeetCode 3483 following your requested format: Problem Understanding The problem asks us to determine the number of distinct three-digit even numbers that can be formed from an array of digits called digits . Each digit in the array can only be used once per number , but the array may contain...

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LeetCode 3431 - Minimum Unlocked Indices to Sort Nums

LeetCode Problem 3431 Difficulty: 🟡 Medium Topics: Array, Hash Table Solution LeetCode 3431 - Minimum Unlocked Indices to Sort Nums Problem Understanding We are given two arrays of equal length: nums , where every value is either 1 , 2 , or 3 locked , where each value is either 0 or 1 The array is considered sortable if we can repeatedly perform certain adjacent swaps until the array becomes...

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LeetCode 3443 - Maximum Manhattan Distance After K Changes

LeetCode Problem 3443 Difficulty: 🟡 Medium Topics: Hash Table, Math, String, Counting Solution Problem Understanding The input is a string s consisting of the four cardinal directions 'N' , 'S' , 'E' , and 'W' . Starting from the origin (0, 0) , we perform the moves one by one in the order given by the string. After every step, we can compute the Manhattan distance from the origin: $|x|+|y|$...

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LeetCode 3434 - Maximum Frequency After Subarray Operation

LeetCode Problem 3434 Difficulty: 🟡 Medium Topics: Array, Hash Table, Dynamic Programming, Greedy, Enumeration, Prefix Sum Solution LeetCode 3434 - Maximum Frequency After Subarray Operation Problem Understanding We are given an array nums and a target value k . We must perform exactly one operation: Choose a contiguous subarray nums[i..j] . Choose an integer x . Add x to every element inside that subarray. After performing this operation, some elements...

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LeetCode 3025 - Find the Number of Ways to Place People I

LeetCode Problem 3025 Difficulty: 🟡 Medium Topics: Array, Math, Geometry, Sorting, Enumeration Solution Correctness The proposed solution does not address the actual content of the TAOCP exercise. The exercise is about constructing and explaining numerical instability in floating point evaluation of algebraically equivalent expressions, but the “solution” instead discusses Python runtime errors, missing imports, and input parsing issues. These are unrelated to floating point arithmetic, polynomial rearrangement, or conditioning. A...

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LeetCode 3432 - Count Partitions with Even Sum Difference

LeetCode Problem 3432 Difficulty: 🟢 Easy Topics: Array, Math, Prefix Sum Solution LeetCode 3432 - Count Partitions with Even Sum Difference Problem Understanding The problem gives us an integer array nums of length n . We must consider every possible partition point between elements, where the array is split into two non-empty parts. For a partition at index i : The left subarray is nums[0...i] . The right subarray is...

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LeetCode 3426 - Manhattan Distances of All Arrangements of Pieces

LeetCode Problem 3426 Difficulty: 🔴 Hard Topics: Math, Combinatorics Solution LeetCode 3426 - Manhattan Distances of All Arrangements of Pieces Problem Understanding We are given an m × n grid and must place exactly k identical pieces onto distinct cells. Every possible placement of these k pieces is considered a valid arrangement. For a single arrangement, we compute the sum of Manhattan distances between every pair of placed pieces. The...

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LeetCode 3404 - Count Special Subsequences

LeetCode Problem 3404 Difficulty: 🟡 Medium Topics: Array, Hash Table, Math, Enumeration Solution LeetCode 3404. Count Special Subsequences Problem Understanding We are given an array nums of positive integers and need to count how many subsequences of length four satisfy a specific multiplicative relationship. A valid subsequence consists of indices (p, q, r, s) such that: p < q < r < s nums[p] * nums[r] == nums[q] * nums[s]...

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LeetCode 3405 - Count the Number of Arrays with K Matching Adjacent Elements

LeetCode Problem 3405 Difficulty: 🔴 Hard Topics: Math, Combinatorics Solution LeetCode 3405. Count the Number of Arrays with K Matching Adjacent Elements Problem Understanding We are given three integers: n , the length of the array. m , the number of possible values each element may take, namely integers in the range [1, m] . k , the exact number of adjacent pairs that must be equal. An array arr...

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LeetCode 3381 - Maximum Subarray Sum With Length Divisible by K

LeetCode Problem 3381 Difficulty: 🟡 Medium Topics: Array, Hash Table, Prefix Sum Solution LeetCode 3381 - Maximum Subarray Sum With Length Divisible by K Problem Understanding We are given an integer array nums and an integer k . We must find a contiguous subarray whose length is divisible by k , and among all such valid subarrays, return the maximum possible sum. A subarray is a contiguous segment of the...

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LeetCode 3313 - Find the Last Marked Nodes in Tree

LeetCode Problem 3313 Difficulty: 🔴 Hard Topics: Tree, Depth-First Search Solution Problem Understanding We are given an undirected tree with n nodes. A tree is a connected graph with exactly n - 1 edges and no cycles. For every node i , we perform the following process: Node i is marked at time t = 0 . Every second afterward, any unmarked node that is adjacent to at least one...

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LeetCode 2933 - High-Access Employees

LeetCode Problem 2933 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Sorting Solution LeetCode 2933 - High-Access Employees Problem Understanding This problem provides a list of employee access records. Each record contains two pieces of information: The employee's name. A timestamp in 24-hour "HHMM" format. All timestamps belong to the same day, so there is no need to handle dates or day transitions. An employee is considered high-access if they...

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LeetCode 1787 - Make the XOR of All Segments Equal to Zero

LeetCode Problem 1787 Difficulty: 🔴 Hard Topics: Array, Hash Table, Dynamic Programming, Bit Manipulation, Counting Solution LeetCode 1787. Make the XOR of All Segments Equal to Zero Problem Understanding We are given an array nums and an integer k . Every contiguous segment of length k must have XOR equal to 0 after we perform some modifications to the array. Our goal is to change as few elements as possible....

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LeetCode 3191 - Minimum Operations to Make Binary Array Elements Equal to One I

LeetCode Problem 3191 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation, Queue, Sliding Window, Prefix Sum Solution Problem Understanding The problem presents a binary array nums of length at least 3, containing only 0s and 1s. The allowed operation is to select any three consecutive elements and flip all of them, meaning each 0 becomes 1 and each 1 becomes 0. The goal is to determine the minimum number of such...

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LeetCode 3310 - Remove Methods From Project

LeetCode Problem 3310 Difficulty: 🟡 Medium Topics: Depth-First Search, Breadth-First Search, Graph Theory Solution Understood. For any TAOCP Volume 1 exercise you provide, I will write the solution in the style of a rigorous solution manual: Use Knuth's notation and terminology from the relevant section. State precisely what is to be proved or computed. Justify every algebraic manipulation, combinatorial argument, and algorithmic step. Omit unnecessary exposition and motivational commentary. Present...

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LeetCode 3158 - Find the XOR of Numbers Which Appear Twice

LeetCode Problem 3158 Difficulty: 🟢 Easy Topics: Array, Hash Table, Bit Manipulation Solution Problem Understanding This problem asks us to find all numbers in the array that appear exactly twice and compute the bitwise XOR of those numbers. The input is an integer array nums . The problem guarantees that every value appears either once or twice, never more than twice. Our task is not to count how many duplicate...

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LeetCode 3004 - Maximum Subtree of the Same Color

LeetCode Problem 3004 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Tree, Depth-First Search Solution Problem Understanding We are given a rooted tree with n nodes, where node 0 is the root. The input edges describes the tree structure. Each entry edges[i] = [u, v] indicates that there is an undirected edge between nodes u and v . Since the problem guarantees that the graph is a tree rooted at node...

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LeetCode 3660 - Jump Game IX

LeetCode Problem 3660 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding The problem asks us to determine, for each position in an array nums , the maximum value that can be reached by making a series of jumps under strict rules. From any index i , we can jump forward to an index j > i only if nums[j] < nums[i] , or jump backward to an index...

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LeetCode 3774 - Absolute Difference Between Maximum and Minimum K Elements

LeetCode Problem 3774 Difficulty: 🟢 Easy Topics: Array, Sorting Solution Problem Understanding The problem asks us to calculate the absolute difference between the sum of the k largest elements and the sum of the k smallest elements in a given array nums . In other words, we first need to identify the k smallest values, sum them up, then identify the k largest values, sum them, and finally compute the...

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LeetCode 3738 - Longest Non-Decreasing Subarray After Replacing at Most One Element

LeetCode Problem 3738 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding == 5 # already non-decreasing edge cases assert Solution().

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LeetCode 3438 - Find Valid Pair of Adjacent Digits in String

LeetCode Problem 3438 Difficulty: 🟢 Easy Topics: Hash Table, String, Counting Solution Problem Understanding The problem gives us a string s containing only digits from '1' to '9' . We need to find the first adjacent pair of digits that satisfies two conditions. First, the two digits in the pair must be different. A pair like "22" or "55" is never valid. Second, each digit in the pair must appear...

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LeetCode 3430 - Maximum and Minimum Sums of at Most Size K Subarrays

LeetCode Problem 3430 Difficulty: 🔴 Hard Topics: Array, Math, Stack, Monotonic Stack Solution Problem Understanding We are remains efficient even at the maximum constraint limit.

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LeetCode 3421 - Find Students Who Improved

LeetCode Problem 3421 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This This ensures that performance in one subject never affects another subject's result.

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LeetCode 3394 - Check if Grid can be Cut into Sections

LeetCode Problem 3394 Difficulty: 🟡 Medium Topics: Array, Sorting Solution

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LeetCode 3675 - Minimum Operations to Transform String

LeetCode Problem 3675 Difficulty: 🟡 Medium Topics: String, Greedy Solution Problem Understanding We are given a string s consisting of lowercase English letters. An operation chooses a character value c and simultaneously replaces every occurrence of c in the current string with the next letter of the alphabet. The alphabet is circular, so 'z' becomes 'a' . The important detail is that an operation acts on a letter value, not...

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LeetCode 3671 - Sum of Beautiful Subsequences

LeetCode Problem 3671 Difficulty: 🔴 Hard Topics: Array, Math, Binary Indexed Tree, Number Theory Solution Problem Understanding Let a subsequence of nums be any sequence multiples. citeturn0search1turn0search2 check whether it is strictly increasing, compute its GCD, and add that GCD to the answer. This is correct because every valid subsequence is examined exactly once. Unfortunately, there are 2^n subsequences. Even for `n = um queries efficiently. citeturn0search1turn0 Force | O(2^n...

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LeetCode 3639 - Minimum Time to Activate String

LeetCode Problem 3639 Difficulty: 🟡 Medium Topics: Array, Binary Search Solution Problem Understanding We are given a string s of length n and a permutation array order . At time t = 0 , the character at index order[0] is replaced with '*' . At time t = 1 , the character at index order[1] is also replaced with '*' . This process continues until every position has eventually been...

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LeetCode 3633 - Earliest Finish Time for Land and Water Rides I

LeetCode Problem 3633 Difficulty: 🟢 Easy Topics: Array, Two Pointers, Binary Search, Greedy, Sorting Solution Problem Understanding The problem asks us to determine the earliest possible time a tourist can finish exactly one land ride and one water ride at a theme park, where rides may be taken in either order. Each ride has a start time , representing when it becomes available, and a duration , representing how long...

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LeetCode 3634 - Minimum Removals to Balance Array

LeetCode Problem 3634 Difficulty: 🟡 Medium Topics: Array, Binary Search, Sliding Window, Sorting Solution Problem Understanding The problem asks us to transform a given integer array nums into a balanced array with the minimum number of removals . An array is defined as balanced if its maximum element does not exceed k times its minimum element. Formally, for array A , it must satisfy: $$\max(A) \le k \cdot \min(A)$$ We...

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LeetCode 3621 - Number of Integers With Popcount-Depth Equal to K I

LeetCode Problem 3621 Difficulty: 🔴 Hard Topics: Math, Dynamic Programming, Bit Manipulation, Combinatorics Solution Problem Understanding This problem asks us to count integers x in the range [1, n] such that the popcount-depth of x is exactly k . The popcount-depth is defined via a sequence p0, p1, ... where p0 = x and pi+1 = popcount(pi) for all i ≥ 0 . The popcount of a number is the...

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LeetCode 3616 - Number of Student Replacements

LeetCode Problem 3616 Difficulty: 🟡 Medium Topics: Array, Simulation Solution Problem Understanding The problem models a simple selection process among students arriving one by one. Each student has a rank, where a smaller rank value represents a better student. The first arriving student is automatically selected. As additional students arrive, we compare their rank against the rank of the currently selected student. If the new student has a strictly better...

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LeetCode 3615 - Longest Palindromic Path in Graph

LeetCode Problem 3615 Difficulty: 🔴 Hard Topics: String, Dynamic Programming, Bit Manipulation, Graph Theory, Bitmask Solution Problem Understanding We are given an undirected graph with n ≤ 14 vertices. Each vertex has a character label. We may choose any simple path in the graph, meaning a sequence of adjacent vertices in which no vertex is visited more than once. If the labels encountered along that path form a palindrome, the...

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LeetCode 3610 - Minimum Number of Primes to Sum to Target

LeetCode Problem 3610 Difficulty: 🟡 Medium Topics: Array, Math, Dynamic Programming, Number Theory Solution Problem Understanding The problem requires us to determine the minimum number of prime numbers from the first m primes whose sum equals n . A multiset is allowed, meaning each prime may be chosen multiple times. The input integers n and m specify the target sum and the number of primes available, respectively. The output is...

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LeetCode 3600 - Maximize Spanning Tree Stability with Upgrades

LeetCode Problem 3600 Difficulty: 🔴 Hard Topics: Binary Search, Greedy, Union-Find, Graph Theory, Minimum Spanning Tree Solution Problem Understanding This problem asks us to determine the maximum possible stability of a spanning tree built from a weighted, undirected graph with certain constraints. Each edge in the graph has a strength and a mandatory flag . A mandatory edge ( musti == 1 ) must appear in the spanning tree, and...

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LeetCode 3890 - Integers With Multiple Sum of Two Cubes

LeetCode Problem 3890 Difficulty: 🟡 Medium Topics: Hash Table, Sorting, Counting, Enumeration Solution Problem Understanding The problem asks us to find all integers x less than or equal to a given integer n such that x can be expressed as the sum of cubes of two positive integers in at least two distinct ways . A “distinct way” means that the pairs (a, b) used to form x are different,...

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LeetCode 3792 - Sum of Increasing Product Blocks

LeetCode Problem 3792 Difficulty: 🟡 Medium Topics: Math, Simulation Solution Problem Understanding The problem defines a sequence of blocks, where each block contains the product of a consecutive range of integers. The pattern works as follows: The 1st block contains only 1 The 2nd block contains 2 × 3 The 3rd block contains 4 × 5 × 6 The 4th block contains 7 × 8 × 9 × 10 Notice...

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LeetCode 3889 - Mirror Frequency Distance

LeetCode Problem 3889 Difficulty: 🟡 Medium Topics: Hash Table, String, Counting Solution LeetCode 3889 - Mirror Frequency Distance Problem Understanding We are given a string s containing only lowercase English letters ( a-z ) and digits ( 0-9 ). Each character has a corresponding mirror character: Letters are mirrored across the alphabet. a ↔ z b ↔ y c ↔ x and so on. Digits are mirrored across the digit...

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LeetCode 3875 - Construct Uniform Parity Array I

LeetCode Problem 3875 Difficulty: 🟢 Easy Topics: Array, Math Solution Problem Understanding The problem asks us to determine if it is possible to construct a new array nums2 of the same length as nums1 where all elements are either all odd or all even. For each element nums2[i] , we can either copy the corresponding element from nums1[i] directly, or we can set it as the difference between nums1[i] and...

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LeetCode 3791 - Number of Balanced Integers in a Range

LeetCode Problem 3791 Difficulty: 🔴 Hard Topics: Dynamic Programming Solution Here is the full, detailed technical solution guide for LeetCode 3791 - Number of Balanced Integers in a Range, following your requested structure. Problem Understanding The problem asks us to count all integers between low and high inclusive that are balanced . An integer is defined as balanced if it meets two conditions. First, it must have at least two...

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LeetCode 3885 - Design Event Manager

LeetCode Problem 3885 Difficulty: 🟡 Medium Topics: Array, Hash Table, Design, Heap (Priority Queue), Ordered Set Solution Problem Understanding The problem asks us to design an EventManager class that manages a set of events, each identified by a unique eventId and associated with a priority . The manager must support two primary operations: updating the priority of an active event and retrieving the highest-priority active event, with ties broken by...

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LeetCode 3790 - Smallest All-Ones Multiple

LeetCode Problem 3790 Difficulty: 🟡 Medium Topics: Hash Table, Math Solution Problem Understanding This problem asks us to find the smallest positive integer composed entirely of the digit 1 that is divisible by a given integer k . The input k is guaranteed to be between 2 and 100,000. We are asked not for the number itself, but for the number of digits in this number, which simplifies the task...

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LeetCode 3884 - First Matching Character From Both Ends

LeetCode Problem 3884 Difficulty: 🟢 Easy Topics: Two Pointers, String Solution LeetCode 3884 - First Matching Character From Both Ends Problem Understanding This problem gives us a string s of length n consisting of lowercase English letters. For every index i , we compare two characters: The character at position i , which is s[i] The character at the mirrored position from the other end, which is s[n - i...

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LeetCode 3882 - Minimum XOR Path in a Grid

LeetCode Problem 3882 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Bit Manipulation, Matrix Solution LeetCode 3882 - Minimum XOR Path in a Grid Problem Understanding We are given an m × n grid of integers. Starting from the top-left cell (0, 0) , we must reach the bottom-right cell (m - 1, n - 1) by moving only right or down. For every path, we compute its cost as the...

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LeetCode 3789 - Minimum Cost to Acquire Required Items

LeetCode Problem 3789 Difficulty: 🟡 Medium Topics: Math, Greedy Solution Problem Understanding This problem asks us to determine the minimum cost required to acquire a set of items that satisfy two separate type requirements. We have three types of items: type 1, type 2, and type 3. Type 1 contributes only to the first requirement, type 2 contributes only to the second requirement, and type 3 contributes to both requirements...

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LeetCode 3883 - Count Non Decreasing Arrays With Given Digit Sums

LeetCode Problem 3883 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Prefix Sum Solution Problem Understanding The problem asks us to compute the number of non-decreasing arrays of integers where each integer satisfies a specific digit sum constraint. Specifically, we are given an array digitSum of length n , where digitSum[i] represents the required sum of digits for the i -th element in the array. We must construct arrays arr of...

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LeetCode 3880 - Minimum Absolute Difference Between Two Values

LeetCode Problem 3880 Difficulty: 🟢 Easy Topics: Array, Enumeration Solution LeetCode 3880 - Minimum Absolute Difference Between Two Values Problem Understanding The problem gives us an integer array nums where every element is guaranteed to be one of three values: 0 , 1 , or 2 . A pair of indices (i, j) is considered valid when: nums[i] == 1 nums[j] == 2 For every valid pair, we compute the...

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LeetCode 3788 - Maximum Score of a Split

LeetCode Problem 3788 Difficulty: 🟡 Medium Topics: Array, Prefix Sum Solution Problem Understanding The problem asks us to maximize a "score" obtained by splitting an integer array nums at a valid index i . For each split index i , the score is calculated as the sum of all elements from the beginning of the array up to i ( prefixSum ) minus the minimum value in the remaining elements...

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LeetCode 3881 - Direction Assignments with Exactly K Visible People

LeetCode Problem 3881 Difficulty: 🟡 Medium Topics: Math, Combinatorics Solution LeetCode 3881 - Direction Assignments with Exactly K Visible People Problem Understanding We are given n people standing in a line, indexed from 0 to n - 1 . Each person independently chooses one of two directions: 'L' means the person is visible only to people on their right. 'R' means the person is visible only to people on their...

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LeetCode 3786 - Total Sum of Interaction Cost in Tree Groups

LeetCode Problem 3786 Difficulty: 🔴 Hard Topics: Array, Tree, Depth-First Search Solution I can do this, but I need the actual problem details for LeetCode 3786 - Total Sum of Interaction Cost in Tree Groups to ensure the algorithm, proof, and code are correct. The statement you pasted appears complete, but this problem is recent and correctness matters for a Hard tree problem. I need to verify whether there are...

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LeetCode 3878 - Count Good Subarrays

LeetCode Problem 3878 Difficulty: 🔴 Hard Topics: Array, Stack, Bit Manipulation, Monotonic Stack Solution LeetCode 3878 - Count Good Subarrays Problem Understanding We are given an integer array nums , and we must count how many subarrays are good . A subarray is considered good if the bitwise OR of all elements in that subarray is equal to at least one element that appears inside the same subarray. Suppose a...

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LeetCode 3879 - Maximum Distinct Path Sum in a Binary Tree

LeetCode Problem 3879 Difficulty: 🟡 Medium Topics: Hash Table, Tree, Depth-First Search, Binary Tree Solution Problem Understanding The problem asks us to find the maximum sum of node values along a path in a binary tree such that all values in the path are distinct . The path can start and end at any node, does not need to pass through the root, and must consist of connected nodes. Each...

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LeetCode 3784 - Minimum Deletion Cost to Make All Characters Equal

LeetCode Problem 3784 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Enumeration Solution Problem Understanding The problem asks us to minimize the total cost of deleting characters from a string such that the resulting string contains only one unique character . We are given a string s of length n and an array cost of the same length, where cost[i] is the cost of deleting the character s[i] . The...

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LeetCode 3877 - Minimum Removals to Achieve Target XOR

LeetCode Problem 3877 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Bit Manipulation Solution LeetCode 3877 - Minimum Removals to Achieve Target XOR Problem Understanding We are given an array nums and a target value target . We may remove any subset of elements from the array, including removing none of them or even removing all of them. After performing the removals, the remaining elements form a new array. The bitwise...

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LeetCode 3782 - Last Remaining Integer After Alternating Deletion Operations

LeetCode Problem 3782 Difficulty: 🔴 Hard Topics: Math, Recursion Solution Before I write the full guide, I want to confirm one critical detail because the examples appear inconsistent with the stated operations. The statement says: Operation 1: Starting from the left, delete every second number Example transforms [1,2,3,4,5,6,7,8] → [1,3,5,7] This means it is deleting positions 2,4,6,8 and keeping odd positions . However, for Operation 2 on [1,3,5,7] , the...

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LeetCode 3781 - Maximum Score After Binary Swaps

LeetCode Problem 3781 Difficulty: 🟡 Medium Topics: Array, String, Greedy, Heap (Priority Queue) Solution Before I write the full guide, I need one clarification: can you confirm the exact LeetCode 3781 problem details or provide the official title/link? “Maximum Score After Binary Swaps” does not match a problem I can reliably identify from memory, and I want to ensure the algorithm and proof are correct. In particular, I want to...

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LeetCode 3780 - Maximum Sum of Three Numbers Divisible by Three

LeetCode Problem 3780 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting, Heap (Priority Queue) Solution Here is a comprehensive, detailed solution guide for LeetCode 3780 - Maximum Sum of Three Numbers Divisible by Three, following your requested format: Problem Understanding The problem asks us to select exactly three integers from the given integer array nums such that the sum of those three integers is divisible by 3 . Among all possible...

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LeetCode 3876 - Construct Uniform Parity Array II

LeetCode Problem 3876 Difficulty: 🟡 Medium Topics: Array, Math Solution Problem Understanding The problem asks us to determine whether we can construct a new array nums2 from a given array nums1 of distinct integers such that all elements in nums2 have the same parity (all even or all odd). For each index i , we have two options: we can either take nums1[i] directly, or subtract any other element nums1[j]...

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LeetCode 3869 - Count Fancy Numbers in a Range

LeetCode Problem 3869 Difficulty: 🔴 Hard Topics: Math, Dynamic Programming Solution LeetCode 3869 - Count Fancy Numbers in a Range Problem Understanding We are given two integers l and r , and we must count how many integers in the inclusive range [l, r] are fancy . The definition of a fancy number is based on the concept of a good number. A number is good if its digits form...

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LeetCode 3779 - Minimum Number of Operations to Have Distinct Elements

LeetCode Problem 3779 Difficulty: 🟡 Medium Topics: Array, Hash Table Solution Problem Understanding The problem gives us an integer array nums and defines a very specific operation: in one move, we remove the first three elements of the current array. If fewer than three elements remain, we remove everything that is left. We continue performing this operation until one of two conditions becomes true: The array becomes empty. The remaining...

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LeetCode 3873 - Maximum Points Activated with One Addition

LeetCode Problem 3873 Difficulty: 🔴 Hard Topics: Array, Hash Table, Union-Find Solution Problem Understanding The problem is asking us to simulate a chain reaction of activations on a set of 2D points. Each point is defined by its (x, y) coordinates and all points are distinct. When a point is activated, any point sharing the same x coordinate or y coordinate becomes activated as well. This activation propagates recursively: newly...

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LeetCode 3872 - Longest Arithmetic Sequence After Changing At Most One Element

LeetCode Problem 3872 Difficulty: 🟡 Medium Topics: Array, Enumeration Solution Problem Understanding The problem requires us to find the longest arithmetic subarray from a given array of integers nums if we are allowed to modify at most one element. An arithmetic subarray is a contiguous sequence in which the difference between consecutive elements is constant. The input, nums , is an integer array of length between 4 and 105, and...

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LeetCode 3871 - Count Commas in Range II

LeetCode Problem 3871 Difficulty: 🟡 Medium Topics: Math Solution LeetCode 3871 - Count Commas in Range II Problem Understanding The problem asks us to count the total number of commas that appear when writing every integer from 1 through n using standard comma-separated number formatting. In standard formatting, commas are inserted every three digits from the right: 1 through 999 contain no commas. 1,000 through 999,999 contain one comma each....

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LeetCode 3870 - Count Commas in Range

LeetCode Problem 3870 Difficulty: 🟢 Easy Topics: Math Solution LeetCode 3870 - Count Commas in Range Problem Understanding The problem asks us to count how many commas appear when writing every integer from 1 through n using standard number formatting. In standard formatting, commas are inserted every three digits from the right side of the number. For example: 999 contains 0 commas. 1,000 contains 1 comma. 12,345 contains 1 comma....

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LeetCode 3778 - Minimum Distance Excluding One Maximum Weighted Edge

LeetCode Problem 3778 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding We are given a connected, weighted, undirected graph with n nodes numbered from 0 to n - 1 . Every edge is represented as [u, v, w] , meaning there is a bidirectional edge between nodes u and v with positive weight w . The objective is to find the minimum cost path from node 0 to node n...

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LeetCode 3868 - Minimum Cost to Equalize Arrays Using Swaps

LeetCode Problem 3868 Difficulty: 🟡 Medium Topics: Array, Hash Table, Greedy, Counting Solution Problem Understanding The problem requires us to make two integer arrays nums1 and nums2 identical by performing swaps. There are two types of swaps: swaps within the same array, which are free, and swaps between arrays at the same index, which cost 1 per operation. The goal is to determine the minimum cost to make the arrays...

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LeetCode 3867 - Sum of GCD of Formed Pairs

LeetCode Problem 3867 Difficulty: 🟡 Medium Topics: Array, Math, Two Pointers, Simulation, Number Theory Solution LeetCode 3867 - Sum of GCD of Formed Pairs Problem Understanding We are given an integer array nums of length n . For every index i , we first compute: mxi , the maximum value among nums[0...i] prefixGcd[i] = gcd(nums[i], mxi) This creates a new array called prefixGcd . After that, we sort prefixGcd in...

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LeetCode 3866 - First Unique Even Element

LeetCode Problem 3866 Difficulty: 🟢 Easy Topics: Array, Hash Table, Counting Solution Problem Understanding The problem asks us to find the first even integer in an array that appears exactly once . In other words, we need to traverse the array and identify even numbers, count their occurrences, and return the earliest one that occurs only a single time. If there is no such even number, we return -1 ....

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LeetCode 3775 - Reverse Words With Same Vowel Count

LeetCode Problem 3775 Difficulty: 🟡 Medium Topics: Two Pointers, String, Simulation Solution Problem Understanding The problem requires processing a string s consisting of lowercase English words separated by single spaces. The first task is to count the number of vowels in the first word . Then, for each subsequent word in the string, if the word has the same number of vowels as the first word, it should be reversed....

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LeetCode 3865 - Reverse K Subarrays

LeetCode Problem 3865 Difficulty: 🟡 Medium Topics: Array, Two Pointers Solution Problem Understanding The problem asks us to take an integer array nums of length n and divide it into k contiguous subarrays of equal length, then reverse each subarray individually. The resulting array should preserve the order of the subarrays but reflect the reversal within each one. For example, if nums = [1,2,4,3,5,6] and k = 3 , each...

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LeetCode 3864 - Minimum Cost to Partition a Binary String

LeetCode Problem 3864 Difficulty: 🔴 Hard Topics: String, Divide and Conquer, Prefix Sum Solution LeetCode 3864 - Minimum Cost to Partition a Binary String Problem Understanding We are given a binary string s , where each character represents whether an element is sensitive: '1' means the element is sensitive. '0' means the element is not sensitive. The entire string initially forms one segment. Every segment has a storage cost that...

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LeetCode 3773 - Maximum Number of Equal Length Runs

LeetCode Problem 3773 Difficulty: 🟡 Medium Topics: Hash Table, String, Counting Solution Problem Understanding The problem asks us to analyze a string s consisting of lowercase English letters and identify runs , which are contiguous sequences of identical characters that cannot be extended further. For example, in "aaabaaa" , the runs are "aaa" , "b" , and "aaa" . The goal is to select runs that all have the same...

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LeetCode 3862 - Find the Smallest Balanced Index

LeetCode Problem 3862 Difficulty: 🟡 Medium Topics: Array, Prefix Sum Solution LeetCode 3862 - Find the Smallest Balanced Index Problem Understanding We are given an integer array nums , and we need to find the smallest index i that satisfies a special balance condition. For a given index i : The left sum is the sum of all elements strictly before i , that is, nums[0] + nums[1] + ......

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LeetCode 3772 - Maximum Subgraph Score in a Tree

LeetCode Problem 3772 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Tree, Depth-First Search Solution Problem Understanding The problem asks us to compute, for each node in a tree, the maximum score of a connected subgraph that includes that node. The tree is represented as an undirected graph with n nodes and n - 1 edges. Each node has a value indicating whether it is good ( 1 ) or bad...

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LeetCode 3863 - Minimum Operations to Sort a String

LeetCode Problem 3863 Difficulty: 🟡 Medium Topics: String Solution Problem Understanding This problem is asking us to determine the minimum number of substring sort operations needed to make a string s sorted in non-descending alphabetical order . We are allowed to sort any substring of s , but we cannot sort the entire string at once. The goal is to find the smallest number of operations to achieve a fully...

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LeetCode 3771 - Total Score of Dungeon Runs

LeetCode Problem 3771 Difficulty: 🟡 Medium Topics: Array, Binary Search, Prefix Sum Solution Problem Understanding The problem describes a dungeon with n rooms, where entering room i reduces your health points by damage[i] . After taking this damage, if your remaining health is at least requirement[i] , you earn 1 point for that room. You can start your dungeon run at any room j (1-indexed) and proceed through the rest...

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LeetCode 3860 - Unique Email Groups

LeetCode Problem 3860 Difficulty: 🟡 Medium Topics: Array, Hash Table, String Solution LeetCode 3860 - Unique Email Groups Problem Understanding This problem asks us to determine how many distinct email groups exist after applying a specific normalization process to every email address. Each email consists of two parts separated by the '@' character: The local name appears before '@' . The domain name appears after '@' . Before comparing emails,...

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LeetCode 3858 - Minimum Bitwise OR From Grid

LeetCode Problem 3858 Difficulty: 🟡 Medium Topics: Array, Greedy, Bit Manipulation, Matrix Solution LeetCode 3858 - Minimum Bitwise OR From Grid Problem Understanding We are given an m x n grid of positive integers. From each row, we must choose exactly one value. After making one choice per row, we compute the bitwise OR of all selected values. Our goal is to make that final OR value as small as...

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LeetCode 3769 - Sort Integers by Binary Reflection

LeetCode Problem 3769 Difficulty: 🟢 Easy Topics: Array, Sorting Solution Problem Understanding This problem asks us to sort an array of positive integers based on a transformation called binary reflection . The binary reflection of a number is obtained by converting the number to its binary representation, reversing the order of the bits (ignoring leading zeros), and then interpreting the resulting binary string as a decimal integer. For example, the...

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LeetCode 3857 - Minimum Cost to Split into Ones

LeetCode Problem 3857 Difficulty: 🟡 Medium Topics: Math, Dynamic Programming Solution LeetCode 3857 - Minimum Cost to Split into Ones Problem Understanding We are given a single integer n . Starting with this integer, we repeatedly perform split operations until every resulting piece is equal to 1 . A split operation takes some integer x and divides it into two positive integers a and b such that: $$a + b...

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LeetCode 3767 - Maximize Points After Choosing K Tasks

LeetCode Problem 3767 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting, Heap (Priority Queue) Solution Problem Understanding The problem gives two integer arrays, technique1 and technique2 , each of length n , representing two ways to complete n tasks. Completing the i th task with technique1 yields technique1[i] points, while using technique2 yields technique2[i] points. You are also given an integer k , which specifies the minimum number of tasks that...

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LeetCode 3856 - Trim Trailing Vowels

LeetCode Problem 3856 Difficulty: 🟢 Easy Topics: String Solution LeetCode 3856 - Trim Trailing Vowels Problem Understanding This problem asks us to remove all vowels that appear at the end of a given string. The input is a string s consisting only of lowercase English letters. A vowel is defined as one of the five characters: 'a' , 'e' , 'i' , 'o' , or 'u' . The goal is...

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LeetCode 3854 - Minimum Operations to Make Array Parity Alternating

LeetCode Problem 3854 Difficulty: 🟡 Medium Topics: Array, Greedy Solution Problem Understanding We are given an integer array nums . An array is called parity alternating when every pair of adjacent elements has different parity. In other words, the parity pattern must alternate between even and odd. For an array of length n , there are only two possible valid parity patterns: Even, Odd, Even, Odd, ... Odd, Even, Odd,...

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LeetCode 3766 - Minimum Operations to Make Binary Palindrome

LeetCode Problem 3766 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Binary Search, Bit Manipulation Solution Problem Understanding This problem asks us to find the minimum number of increment or decrement operations needed to convert each number in a list into a binary palindrome . A binary palindrome is a number whose binary representation reads the same forwards and backwards once leading zeros are removed. For example, the number 5 in...

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LeetCode 3855 - Sum of K-Digit Numbers in a Range

LeetCode Problem 3855 Difficulty: 🔴 Hard Topics: Math, Divide and Conquer, Combinatorics, Number Theory Solution LeetCode 3855 - Sum of K-Digit Numbers in a Range Problem Understanding We are given three integers l , r , and k . For every digit position, we may independently choose any digit from the inclusive range [l, r] . We then form all possible numbers consisting of exactly k digits. A key detail...

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LeetCode 3763 - Maximum Total Sum with Threshold Constraints

LeetCode Problem 3763 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting, Heap (Priority Queue) Solution Problem Understanding The problem gives you two integer arrays, nums and threshold , each of length n . Each index i represents a value nums[i] you can add to a running total, but you can only choose that index when the current step is at least threshold[i] . You start at step = 1 and increment...

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LeetCode 3852 - Smallest Pair With Different Frequencies

LeetCode Problem 3852 Difficulty: 🟢 Easy Topics: Array, Hash Table, Counting Solution LeetCode 3852 - Smallest Pair With Different Frequencies Problem Understanding This problem gives us an integer array nums and asks us to find a pair of distinct values [x, y] that satisfies two conditions: x < y The frequency of x in the array is different from the frequency of y . Among all valid pairs, we must...

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LeetCode 3853 - Merge Close Characters

LeetCode Problem 3853 Difficulty: 🟡 Medium Topics: Hash Table, String Solution Problem Understanding The problem asks us to repeatedly merge close, equal characters in a string s . A character pair is considered close if the distance between their indices is at most k . When a merge occurs, the right character is removed and the string is updated immediately. Merges are performed one at a time, always choosing the...

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LeetCode 3759 - Count Elements With at Least K Greater Values

LeetCode Problem 3759 Difficulty: 🟡 Medium Topics: Array, Binary Search, Divide and Conquer, Sorting, Quickselect Solution Problem Understanding The problem asks us to count how many elements in an array have at least k values that are strictly greater than them. More concretely, for every element nums[i] , we need to determine how many numbers in the array are larger than nums[i] . If that count is at least k...

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LeetCode 3850 - Count Sequences to K

LeetCode Problem 3850 Difficulty: 🔴 Hard Topics: Array, Math, Dynamic Programming, Memoization, Number Theory Solution LeetCode 3850 - Count Sequences to K Problem Understanding We start with a value val = 1 and process the array from left to right. For every element nums[i] , we must choose exactly one of three actions: Multiply the current value by nums[i] Divide the current value by nums[i] Do nothing Division is exact...

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LeetCode 3851 - Maximum Requests Without Violating the Limit

LeetCode Problem 3851 Difficulty: 🟡 Medium Topics: Array, Hash Table, Greedy, Sliding Window, Sorting Solution LeetCode 3851 - Maximum Requests Without Violating the Limit Problem Understanding We are given a list of requests, where each request consists of a user ID and a timestamp. Multiple users can appear in the input, and a user may have multiple requests at different times. For a particular user, the rate limit rule states...

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LeetCode 3758 - Convert Number Words to Digits

LeetCode Problem 3758 Difficulty: 🟡 Medium Topics: String, Trie Solution Problem Understanding The problem asks us to parse a string s that contains lowercase English letters and may include concatenated English words representing digits from 0 to 9. Our goal is to extract all valid number words in order and convert them to their corresponding digit, producing a string of digits. The string must be processed from left to right...

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LeetCode 3847 - Find the Score Difference in a Game

LeetCode Problem 3847 Difficulty: 🟡 Medium Topics: Array, Simulation Solution LeetCode 3847 - Find the Score Difference in a Game Problem Understanding This problem describes a game played over a sequence of rounds. The array nums represents the points awarded in each game, where nums[i] is the number of points available during game i . There are exactly two players. At the beginning: The first player is active. The second...

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LeetCode 3757 - Number of Effective Subsequences

LeetCode Problem 3757 Difficulty: 🔴 Hard Topics: Array, Math, Dynamic Programming, Bit Manipulation, Combinatorics Solution Here’s a complete, detailed technical guide for LeetCode 3757 - Number of Effective Subsequences , following your formatting instructions exactly. Problem Understanding The problem gives us an array of integers, nums , and asks us to determine the number of effective subsequences . The strength of the array is defined as the bitwise OR of...

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LeetCode 3848 - Check Digitorial Permutation

LeetCode Problem 3848 Difficulty: 🟡 Medium Topics: Math, Counting Solution Problem Understanding The problem asks us to determine whether any permutation of the digits of a given integer n forms a digitorial number. A digitorial number is defined as a number equal to the sum of the factorials of its digits. For instance, 145 is digitorial because $1! + 4! + 5! = 145$. The input is a single integer...

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LeetCode 3846 - Total Distance to Type a String Using One Finger

LeetCode Problem 3846 Difficulty: 🟡 Medium Topics: Hash Table, String Solution LeetCode 3846 - Total Distance to Type a String Using One Finger Problem Understanding This problem asks us to calculate the total finger movement required to type a given lowercase string on a special keyboard layout using only one finger. The keyboard is arranged as: q w e r t y u i o p a s d f...

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LeetCode 3844 - Longest Almost-Palindromic Substring

LeetCode Problem 3844 Difficulty: 🟡 Medium Topics: Two Pointers, String, Dynamic Programming Solution LeetCode 3844 - Longest Almost-Palindromic Substring Problem Understanding We are given a string s consisting of lowercase English letters. We must find the length of the longest substring that is almost-palindromic . A substring is almost-palindromic if we can remove exactly one character from that substring and the remaining characters form a palindrome. The key detail is...

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LeetCode 3756 - Concatenate Non-Zero Digits and Multiply by Sum II

LeetCode Problem 3756 Difficulty: 🟡 Medium Topics: Math, String, Prefix Sum Solution Please provide the official LeetCode problem statement or confirm the exact problem details for LeetCode 3756 - Concatenate Non-Zero Digits and Multiply by Sum II . I want to avoid hallucinating the intended optimal approach because this appears to be a very recent/problem-specific question, and correctness matters for the full guide, code, worked examples, and complexity analysis. The...

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LeetCode 3754 - Concatenate Non-Zero Digits and Multiply by Sum I

LeetCode Problem 3754 Difficulty: 🟢 Easy Topics: Math Solution Problem Understanding The problem asks us to process an integer n and construct a new number using only its non-zero digits. These digits must remain in the same order in which they originally appear. After constructing this new integer x , we calculate the sum of its digits and then return the product: $$x \times \text{sum of digits of } x$$...

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LeetCode 3845 - Maximum Subarray XOR with Bounded Range

LeetCode Problem 3845 Difficulty: 🔴 Hard Topics: Array, Bit Manipulation, Trie, Queue, Sliding Window, Prefix Sum, Monotonic Queue Solution Problem Understanding The problem asks us to find a subarray of a given non-negative integer array nums such that the difference between the maximum and minimum elements of the subarray does not exceed a given integer k . Once such a subarray is chosen, we compute the XOR of all its...

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LeetCode 3750 - Minimum Number of Flips to Reverse Binary String

LeetCode Problem 3750 Difficulty: 🟢 Easy Topics: Math, Two Pointers, String, Bit Manipulation Solution Problem Understanding The problem gives us a positive integer n , and asks us to work with its binary representation. First, we convert n into a binary string s without leading zeros. Then, we compute the reverse of that binary string. Our goal is to determine the minimum number of bit flips required so that s...

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LeetCode 3842 - Toggle Light Bulbs

LeetCode Problem 3842 Difficulty: 🟢 Easy Topics: Array, Hash Table, Sorting, Simulation Solution LeetCode 3842 - Toggle Light Bulbs Problem Understanding The problem gives us an array bulbs , where each value represents a light bulb number between 1 and 100 . Initially, there are exactly 100 light bulbs, and every bulb is turned off. We process the array from left to right. For each value bulbs[i] : If that...

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LeetCode 3841 - Palindromic Path Queries in a Tree

LeetCode Problem 3841 Difficulty: 🔴 Hard Topics: Array, String, Divide and Conquer, Tree, Segment Tree Solution LeetCode 3841: Palindromic Path Queries in a Tree Problem Understanding We are given a tree with n nodes. Each node stores a lowercase English letter. The tree is undirected and connected, so there is exactly one simple path between any two nodes. The problem supports two kinds of operations: Update Change the character assigned...

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LeetCode 3839 - Number of Prefix Connected Groups

LeetCode Problem 3839 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Counting Solution LeetCode 3839: Number of Prefix Connected Groups Problem Understanding The problem gives us an array of strings words and an integer k . Two words are considered prefix-connected if they share exactly the same first k characters and they come from different indices in the array. A connected group is defined as a set of words where...

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LeetCode 3838 - Weighted Word Mapping

LeetCode Problem 3838 Difficulty: 🟢 Easy Topics: Array, String, Simulation Solution Problem Understanding The problem provides two inputs: words , an array of lowercase English strings. weights , an array of 26 integers where weights[i] represents the weight assigned to the letter corresponding to index i ( 0 -> 'a' , 1 -> 'b' , ..., 25 -> 'z' ). For every word, we must compute its total weight by...

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LeetCode 3840 - House Robber V

LeetCode Problem 3840 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding The problem is a variation of the classic House Robber problem, but with an additional constraint: each house has a color, and you cannot rob two adjacent houses if they share the same color. We are given two arrays nums and colors of length n . The array nums represents the amount of money at each house,...

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LeetCode 3837 - Delayed Count of Equal Elements

LeetCode Problem 3837 Difficulty: 🟡 Medium Topics: Array, Hash Table, Counting Solution Problem Understanding The problem requires computing a delayed count for each element in an array nums . For an index i , the delayed count is defined as the number of later elements (indices j > i + k ) that are equal to nums[i] . In simpler terms, for each element, we want to count how many...

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LeetCode 3836 - Maximum Score Using Exactly K Pairs

LeetCode Problem 3836 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming Solution LeetCode 3836 - Maximum Score Using Exactly K Pairs Problem Understanding We are given two arrays, nums1 of length n and nums2 of length m , along with an integer k . Our goal is to choose exactly k pairs of indices: $$(i_1, j_1), (i_2, j_2), \dots, (i_k, j_k)$$ such that: $$i_1 < i_2 < \dots < i_k$$ and...

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LeetCode 3835 - Count Subarrays With Cost Less Than or Equal to K

LeetCode Problem 3835 Difficulty: 🟡 Medium Topics: Array, Queue, Monotonic Queue Solution LeetCode 3835 - Count Subarrays With Cost Less Than or Equal to K Problem Understanding We are given an array nums and an integer k . For every subarray nums[l..r] , its cost is defined as: $$(\max(nums[l..r]) - \min(nums[l..r])) \times (r-l+1)$$ The first part measures the range of values inside the subarray, while the second part measures the...

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LeetCode 3834 - Merge Adjacent Equal Elements

LeetCode Problem 3834 Difficulty: 🟡 Medium Topics: Array, Stack, Simulation Solution Problem Understanding The problem asks us to repeatedly merge adjacent equal elements in an integer array nums until no further merges are possible. Specifically, if two consecutive elements are equal, we replace them with their sum. The key points are that we always pick the leftmost pair for merging, and after each merge, the array size decreases by one....

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LeetCode 3833 - Count Dominant Indices

LeetCode Problem 3833 Difficulty: 🟢 Easy Topics: Array, Enumeration Solution LeetCode 3833 - Count Dominant Indices Problem Understanding The problem gives us an integer array nums of length n . For every index i , we must determine whether the element nums[i] is dominant . An index is considered dominant if its value is strictly greater than the average of all elements to its right. In other words, for index...

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LeetCode 3829 - Design Ride Sharing System

LeetCode Problem 3829 Difficulty: 🟡 Medium Topics: Hash Table, Design, Queue, Data Stream Solution Problem Understanding The problem asks us to design a ride sharing system that manages both riders and drivers as they enter the system, and to match them in a first-come, first-served order. The system must track riders who are waiting for rides, drivers who are available, and support canceling rider requests. Inputs include rider and driver...

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LeetCode 3749 - Evaluate Valid Expressions

LeetCode Problem 3749 Difficulty: 🔴 Hard Topics: Hash Table, Math, String, Divide and Conquer, Stack Solution Problem Understanding The problem presents a simplified version of evaluating nested mathematical expressions in string format. The input expression is either a single integer literal, which may be negative, or a nested operation of the form op(a,b) where op is one of the four basic arithmetic operations: add , sub , mul , or...

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LeetCode 3832 - Find Users with Persistent Behavior Patterns

LeetCode Problem 3832 Difficulty: 🔴 Hard Topics: — Solution LeetCode 3832 - Find Users with Persistent Behavior Patterns Problem Understanding The activity table records user actions. Each row contains a user_id , the action_date , and the specific action performed on that date. The primary key is (user_id, action_date, action) , which guarantees that the exact same action for the same user on the same day cannot appear twice. However,...

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LeetCode 3746 - Minimum String Length After Balanced Removals

LeetCode Problem 3746 Difficulty: 🟡 Medium Topics: String, Stack, Counting Solution Before I write the full guide, I want to verify one detail because this appears to be a very new LeetCode problem and correctness matters here. The examples strongly suggest a key simplification: the answer may reduce to the absolute difference between the total number of 'a' and 'b' characters, because any balanced substring has net contribution 0 ,...

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LeetCode 3828 - Final Element After Subarray Deletions

LeetCode Problem 3828 Difficulty: 🟡 Medium Topics: Array, Math, Brainteaser, Game Theory Solution Problem Understanding We are given an integer array nums . Two players, Alice and Bob, repeatedly remove a contiguous subarray from the current array. The only restriction is that the removed subarray cannot be the entire current array, so after every move at least one element remains. After a subarray is removed, the remaining elements are concatenated...

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LeetCode 3741 - Minimum Distance Between Three Equal Elements II

LeetCode Problem 3741 Difficulty: 🟡 Medium Topics: Array, Hash Table Solution Problem Understanding The problem asks us to find three distinct indices (i, j, k) such that the values at those positions are identical: nums[i] == nums[j] == nums[k] Among all such valid triples, we must compute the minimum possible distance , where the distance is defined as: abs(i - j) + abs(j - k) + abs(k - i) If...

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LeetCode 3830 - Longest Alternating Subarray After Removing At Most One Element

LeetCode Problem 3830 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Enumeration Solution Problem Understanding The problem asks us to find the longest alternating subarray in a given integer array nums , where a subarray is defined as consecutive elements. A subarray is considered alternating if the sequence of comparisons between adjacent elements strictly alternates between less-than and greater-than. Formally, for a subarray nums[l..r] , it must satisfy either: nums[l] <...

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LeetCode 3803 - Count Residue Prefixes

LeetCode Problem 3803 Difficulty: 🟢 Easy Topics: Hash Table, String Solution Problem Understanding The problem asks us to analyze prefixes of a string s and count how many of them satisfy a specific condition. A prefix is any substring that starts at the first character and extends to some point in the string. For a prefix to be a residue , the number of distinct characters in that prefix must...

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LeetCode 3826 - Minimum Partition Score

LeetCode Problem 3826 Difficulty: 🔴 Hard Topics: Array, Divide and Conquer, Dynamic Programming, Queue, Prefix Sum, Monotonic Queue Solution LeetCode 3826 - Minimum Partition Score Problem Understanding We are given an array nums and must divide it into exactly k contiguous subarrays. For every subarray, we first compute its sum: $$\text{sumArr} = \sum \text{elements in the subarray}$$ Its value is then defined as: $$\text{value} = \frac{\text{sumArr} \cdot (\text{sumArr}+1)}{2}$$ The score...

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LeetCode 3739 - Count Subarrays With Majority Element II

LeetCode Problem 3739 Difficulty: 🔴 Hard Topics: Array, Hash Table, Divide and Conquer, Segment Tree, Merge Sort, Prefix Sum Solution Here’s a complete, detailed technical solution guide for LeetCode 3739 - Count Subarrays With Majority Element II following your requested format. Problem Understanding The problem asks us to count the number of contiguous subarrays in which a given target element is the majority element . A majority element is one...

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LeetCode 3827 - Count Monobit Integers

LeetCode Problem 3827 Difficulty: 🟢 Easy Topics: Bit Manipulation, Enumeration Solution Problem Understanding The problem asks us to count Monobit integers from 0 to n . A Monobit integer is one where all bits in its binary representation are the same. This means there are only two possibilities for a valid Monobit integer: all zeros or all ones. For instance, 0 ( 0b0 ), 1 ( 0b1 ), 3 (...

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LeetCode 3737 - Count Subarrays With Majority Element I

LeetCode Problem 3737 Difficulty: 🟡 Medium Topics: Array, Hash Table, Divide and Conquer, Segment Tree, Merge Sort, Counting, Prefix Sum Solution Here is a comprehensive, detailed reference guide for LeetCode 3737 - Count Subarrays With Majority Element I , following your formatting requirements exactly. Problem Understanding The problem provides an integer array nums and a target integer. The goal is to count the number of subarrays in which the target...

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LeetCode 3825 - Longest Strictly Increasing Subsequence With Non-Zero Bitwise AND

LeetCode Problem 3825 Difficulty: 🟡 Medium Topics: Array, Binary Search, Bit Manipulation, Enumeration Solution Problem Understanding This problem asks us to find the longest strictly increasing subsequence (LIS) in a given integer array nums , with the additional constraint that the bitwise AND of all elements in the subsequence must be non-zero . In simpler terms, among all sequences you can extract from nums where each number is strictly larger...

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LeetCode 3736 - Minimum Moves to Equal Array Elements III

LeetCode Problem 3736 Difficulty: 🟢 Easy Topics: Array, Math Solution Problem Understanding The problem asks us to determine the minimum number of moves required to make every element in an integer array equal. A move consists of selecting one element and increasing it by exactly 1 . We are not allowed to decrease values, and we can only increment elements. In other words, we need to choose a target value...

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LeetCode 3823 - Reverse Letters Then Special Characters in a String

LeetCode Problem 3823 Difficulty: 🟢 Easy Topics: Two Pointers, String, Simulation Solution LeetCode 3823 - Reverse Letters Then Special Characters in a String Problem Understanding This problem gives us a string s that contains two types of characters: Lowercase English letters ( 'a' to 'z' ) Special characters from the set "!@#$%^&*()" We must perform two independent reversals, in a specific order. First, we extract all lowercase letters from the...

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LeetCode 3733 - Minimum Time to Complete All Deliveries

LeetCode Problem 3733 Difficulty: 🟡 Medium Topics: Math, Binary Search Solution This is a long, structured reference document. To make sure I target the correct problem and avoid producing an incorrect guide, I want to verify one thing first: Can you confirm the exact LeetCode problem number/title? “LeetCode 3733 - Minimum Time to Complete All Deliveries” does not appear to match a known standard problem in my current knowledge, and...

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LeetCode 3731 - Find Missing Elements

LeetCode Problem 3731 Difficulty: 🟢 Easy Topics: Array, Hash Table, Sorting Solution Problem Understanding This problem asks us to reconstruct a missing sequence of integers from a partially incomplete array. We are given an integer array nums containing unique values , and we know an important fact: the array originally contained every integer in a continuous range , but some numbers were removed. Even though some values are missing, the...

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LeetCode 3822 - Design Order Management System

LeetCode Problem 3822 Difficulty: 🟡 Medium Topics: Hash Table, Design Solution LeetCode 3822 - Design Order Management System Problem Understanding This problem asks us to implement a small in-memory order management system that supports four operations on trading orders. Each order has three attributes: orderId , a unique identifier orderType , either "buy" or "sell" price , an integer value When an order is added, it becomes active. Orders remain...

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LeetCode 3730 - Maximum Calories Burnt from Jumps

LeetCode Problem 3730 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Greedy, Sorting Solution Problem Understanding The problem asks us to determine the maximum total calories that can be burned while visiting every block exactly once in an arbitrary order. We are given an integer array heights , where heights[i] represents the height of a block. We begin on the ground at height 0 , and our first jump must go...

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LeetCode 3821 - Find Nth Smallest Integer With K One Bits

LeetCode Problem 3821 Difficulty: 🔴 Hard Topics: Math, Bit Manipulation, Combinatorics Solution Problem Understanding This problem asks us to find the nth smallest positive integer whose binary representation contains exactly k ones . In other words, we are working with numbers that, when written in binary, have a specific number of bits set to 1 . The input consists of two integers: n representing the ordinal position in the sequence...

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LeetCode 3728 - Stable Subarrays With Equal Boundary and Interior Sum

LeetCode Problem 3728 Difficulty: 🟡 Medium Topics: Array, Hash Table, Prefix Sum Solution Problem Understanding The problem asks us to count stable subarrays in an integer array capacity . A subarray capacity[l..r] is stable if it satisfies two conditions: its length is at least 3, and the first and last elements are each equal to the sum of the elements strictly between them. In other words, for a subarray [a0,...

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LeetCode 3819 - Rotate Non Negative Elements

LeetCode Problem 3819 Difficulty: 🟡 Medium Topics: Array, Simulation Solution Problem Understanding The problem asks us to rotate only the non-negative elements of an integer array nums to the left by k positions in a cyclic manner, while leaving all negative elements fixed in their original positions. In other words, the negative numbers act as "anchors" in the array, and the rotation affects only the positive numbers and zeros. After...

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LeetCode 3725 - Count Ways to Choose Coprime Integers from Rows

LeetCode Problem 3725 Difficulty: 🔴 Hard Topics: Array, Math, Dynamic Programming, Matrix, Combinatorics, Number Theory Solution Problem Understanding The problem asks us to determine how many ways we can choose exactly one number from each row of a given m x n matrix such that the greatest common divisor (GCD) of all chosen numbers is 1. In other words, we need to count all valid combinations of one element per...

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LeetCode 3817 - Good Indices in a Digit String

LeetCode Problem 3817 Difficulty: 🟡 Medium Topics: Math, String Solution LeetCode 3817 - Good Indices in a Digit String Problem Understanding We are given a string s consisting only of decimal digits. The string length is n , and indices are zero-based. For every index i , we need to determine whether i is a good index . An index is considered good if there exists a substring ending exactly...

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LeetCode 3818 - Minimum Prefix Removal to Make Array Strictly Increasing

LeetCode Problem 3818 Difficulty: 🟡 Medium Topics: Array Solution Problem Understanding The problem asks us to process an integer array nums and determine the minimum length of a prefix that we can remove so that the remaining array becomes strictly increasing. A prefix is any number of contiguous elements starting from the beginning of the array, including possibly zero elements (meaning we may not need to remove anything). A strictly...

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LeetCode 3724 - Minimum Operations to Transform Array

LeetCode Problem 3724 Difficulty: 🟡 Medium Topics: Array, Greedy Solution Problem Understanding This problem asks us to transform an array nums1 of length n into another array nums2 of length n + 1 using the minimum number of operations. The allowed operations are increasing or decreasing any element of nums1 by 1, or appending any element of nums1 to the end of the array. The goal is to make nums1...

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LeetCode 3816 - Lexicographically Smallest String After Deleting Duplicate Characters

LeetCode Problem 3816 Difficulty: 🔴 Hard Topics: Hash Table, String, Stack, Greedy, Monotonic Stack Solution LeetCode 3816 - Lexicographically Smallest String After Deleting Duplicate Characters Problem Understanding We are given a string s consisting only of lowercase English letters. The allowed operation is very specific: if a character currently appears at least twice in the string, we may delete exactly one occurrence of that character. We may repeat this operation...

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LeetCode 3722 - Lexicographically Smallest String After Reverse

LeetCode Problem 3722 Difficulty: 🟡 Medium Topics: Two Pointers, Binary Search, Enumeration Solution Problem Understanding The problem asks us to find the lexicographically smallest string after performing exactly one reverse operation on a contiguous prefix or suffix of a given string s . The string consists only of lowercase English letters and can have a length up to 1000 characters. In other words, we can either reverse the first k...

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LeetCode 3815 - Design Auction System

LeetCode Problem 3815 Difficulty: 🟡 Medium Topics: Hash Table, Design, Heap (Priority Queue), Ordered Set Solution LeetCode 3815 - Design Auction System Problem Understanding This problem asks us to design a real time auction system that supports inserting, updating, removing, and querying bids efficiently. Each bid is uniquely identified by the pair (userId, itemId) . A user may have at most one active bid for a particular item. If addBid...

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LeetCode 3721 - Longest Balanced Subarray II

LeetCode Problem 3721 Difficulty: 🔴 Hard Topics: Array, Hash Table, Divide and Conquer, Segment Tree, Prefix Sum Solution Problem Understanding The problem requires us to find the length of the longest subarray in an integer array nums where the count of distinct even numbers equals the count of distinct odd numbers . A subarray is a contiguous section of the array, and “distinct” means that duplicate values are counted only...

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LeetCode 3813 - Vowel-Consonant Score

LeetCode Problem 3813 Difficulty: 🟢 Easy Topics: String, Simulation Solution LeetCode 3813 - Vowel-Consonant Score Problem Understanding The problem asks us to compute a score for a given string s . The string may contain lowercase English letters, spaces, and digits. We need to count two quantities: v , the number of vowels in the string. c , the number of consonants in the string. The vowels are exactly the...

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LeetCode 3720 - Lexicographically Smallest Permutation Greater Than Target

LeetCode Problem 3720 Difficulty: 🟡 Medium Topics: Hash Table, String, Greedy, Counting, Enumeration Solution Before I write the full guide, I want to verify one important detail: LeetCode 3720 appears to be a very recent problem , and the exact intended optimal approach depends on the precise judge behavior and hidden constraints. Please confirm that the problem title and statement are exactly: LeetCode 3720 - Lexicographically Smallest Permutation Greater Than...

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LeetCode 3717 - Minimum Operations to Make the Array Beautiful

LeetCode Problem 3717 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Here is the complete, detailed technical solution guide for LeetCode 3717 - Minimum Operations to Make the Array Beautiful following your exact formatting rules. Problem Understanding The problem asks us to transform an integer array nums into a beautiful array . An array is considered beautiful if every element (except the first) is divisible by its previous element. Formally,...

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LeetCode 3812 - Minimum Edge Toggles on a Tree

LeetCode Problem 3812 Difficulty: 🔴 Hard Topics: Tree, Depth-First Search, Graph Theory, Topological Sort, Sorting Solution LeetCode 3812 - Minimum Edge Toggles on a Tree Problem Understanding We are given a tree with n nodes and n - 1 edges. Every node has a binary color represented by the strings start and target . An operation consists of selecting an edge and toggling both of its endpoints. If a node...

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LeetCode 3714 - Longest Balanced Substring II

LeetCode Problem 3714 Difficulty: 🟡 Medium Topics: Hash Table, String, Prefix Sum Solution Problem Understanding The problem gives us a string s that contains only three possible characters: 'a' , 'b' , and 'c' . We must find the longest substring where every distinct character in that substring appears the same number of times . A key detail is that the condition only applies to distinct characters present in the...

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LeetCode 3712 - Sum of Elements With Frequency Divisible by K

LeetCode Problem 3712 Difficulty: 🟢 Easy Topics: Array, Hash Table, Counting Solution Problem Understanding The problem asks us to compute the sum of all elements in the array whose total frequency is divisible by a given integer k . To understand the requirement clearly, we need to focus on two important details: First, we must determine how many times each number appears in the array. This is the element's frequency...

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LeetCode 3811 - Number of Alternating XOR Partitions

LeetCode Problem 3811 Difficulty: 🟡 Medium Topics: Array, Hash Table, Dynamic Programming, Bit Manipulation Solution LeetCode 3811 - Number of Alternating XOR Partitions Problem Understanding We are given an array nums and two distinct target XOR values, target1 and target2 . A partition divides the array into contiguous, non-empty blocks. Every element must belong to exactly one block, and the blocks must cover the entire array. The partition is considered...

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LeetCode 3711 - Maximum Transactions Without Negative Balance

LeetCode Problem 3711 Difficulty: 🟡 Medium Topics: Array, Greedy, Heap (Priority Queue) Solution Here is a complete, detailed technical solution guide for LeetCode 3711 - Maximum Transactions Without Negative Balance , following your formatting instructions precisely. Problem Understanding The problem provides an array transactions of integers representing sequential money movements in an account. Positive values correspond to receiving money, while negative values correspond to sending money. The account starts at...

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LeetCode 3710 - Maximum Partition Factor

LeetCode Problem 3710 Difficulty: 🔴 Hard Topics: Array, Binary Search, Depth-First Search, Breadth-First Search, Union-Find, Graph Theory Solution Problem Understanding The problem asks us to split a set of n points in a 2D Cartesian plane into exactly two non-empty groups, such that the minimum Manhattan distance among all pairs of points within each group (the partition factor) is maximized. The Manhattan distance between points [xi, yi] and [xj, yj]...

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LeetCode 3808 - Find Emotionally Consistent Users

LeetCode Problem 3808 Difficulty: 🟡 Medium Topics: — Solution LeetCode 3808 - Find Emotionally Consistent Users Problem Understanding This problem asks us to analyze user reactions and determine which users exhibit a strong preference for a particular reaction type. The input is a table named reactions , where each row represents a reaction given by a user to a specific content item. The pair (user_id, content_id) is unique, which means...

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LeetCode 3709 - Design Exam Scores Tracker

LeetCode Problem 3709 Difficulty: 🟡 Medium Topics: Array, Binary Search, Design, Prefix Sum Solution Problem Understanding This problem asks us to design a system that tracks Alice's exam scores over time and efficiently computes the total score for any given time interval. The system must support two operations: recording a new exam with a timestamp and score, and querying the total score of exams between two timestamps inclusive. The input...

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LeetCode 3807 - Minimum Cost to Repair Edges to Traverse a Graph

LeetCode Problem 3807 Difficulty: 🟡 Medium Topics: Binary Search, Breadth-First Search, Graph Theory Solution Problem Understanding The problem presents an undirected graph with n nodes labeled from 0 to n-1 and m edges. Each edge has a repair cost, and initially, all edges are damaged. We can spend a certain amount of money to repair all edges whose cost is less than or equal to that amount. After repairing some...

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LeetCode 3704 - Count No-Zero Pairs That Sum to N

LeetCode Problem 3704 Difficulty: 🔴 Hard Topics: Math, Dynamic Programming Solution Problem Understanding The problem asks us to count all pairs of positive integers (a, b) such that their sum equals a given integer n and neither a nor b contains the digit 0 in their decimal representation. These integers are called no-zero integers . The input n is guaranteed to be at least 2 and can be as large...

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LeetCode 3805 - Count Caesar Cipher Pairs

LeetCode Problem 3805 Difficulty: 🟡 Medium Topics: Array, Hash Table, Math, String, Counting Solution LeetCode 3805 - Count Caesar Cipher Pairs Problem Understanding We are given an array words containing n lowercase strings. Every string has the same length m . Two strings are considered similar if we can repeatedly apply the following operation to either string: Shift every character forward by one position in the alphabet. The alphabet wraps...

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LeetCode 3702 - Longest Subsequence With Non-Zero Bitwise XOR

LeetCode Problem 3702 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation Solution Problem Understanding We are given an integer array nums , and we must determine the maximum possible length of a subsequence whose bitwise XOR is not equal to zero . A subsequence is formed by deleting zero or more elements from the array while preserving the relative order of the remaining elements. Unlike subarrays, subsequences do not need to...

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LeetCode 3806 - Maximum Bitwise AND After Increment Operations

LeetCode Problem 3806 Difficulty: 🔴 Hard Topics: Array, Greedy, Bit Manipulation, Sorting Solution Problem Understanding The problem asks us to find the maximum possible bitwise AND of any subset of size m from an array nums after performing up to k increment operations . Each operation allows us to increase any element in the array by 1. The output is the largest integer that can be obtained as the bitwise...

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LeetCode 3804 - Number of Centered Subarrays

LeetCode Problem 3804 Difficulty: 🟡 Medium Topics: Array, Hash Table, Enumeration Solution Problem Understanding The problem asks us to count the number of centered subarrays in a given integer array nums . A subarray is called centered if the sum of its elements is equal to at least one element within that subarray . In simpler terms, for every contiguous sequence of numbers in nums , we need to check...

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LeetCode 3700 - Number of ZigZag Arrays II

LeetCode Problem 3700 Difficulty: 🔴 Hard Topics: Math, Dynamic Programming Solution Problem Understanding The problem asks us to count the number of arrays of length n where each element is in the range [l, r] , no two consecutive elements are equal, and no three consecutive elements are strictly increasing or strictly decreasing. These arrays are termed ZigZag arrays . In other words, for an array A of length n...

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LeetCode 3802 - Number of Ways to Paint Sheets

LeetCode Problem 3802 Difficulty: 🔴 Hard Topics: — Solution Problem Understanding The problem asks us to compute the number of ways to paint n sheets using exactly two distinct colors , subject to constraints on the maximum number of sheets each color can paint. The input consists of an integer n and an array limit of size m , where limit[i] represents the maximum sheets color i can paint. The...

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LeetCode 3799 - Word Squares II

LeetCode Problem 3799 Difficulty: 🟡 Medium Topics: Array, String, Backtracking, Sorting, Enumeration Solution LeetCode 3799 - Word Squares II Problem Understanding We are given an array of distinct 4-letter words. Our goal is to construct every valid word square consisting of exactly four different words: top forms the top row. bottom forms the bottom row. left forms the left column. right forms the right column. Since each word has length...

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LeetCode 3699 - Number of ZigZag Arrays I

LeetCode Problem 3699 Difficulty: 🔴 Hard Topics: Dynamic Programming, Prefix Sum Solution Here is the complete technical solution guide for LeetCode 3699 - Number of ZigZag Arrays I , formatted exactly according to your specifications. Problem Understanding The problem asks us to count arrays of length n where each element is within the range [l, r] and satisfies the ZigZag constraints. A ZigZag array has two main rules: no two...

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LeetCode 3801 - Minimum Cost to Merge Sorted Lists

LeetCode Problem 3801 Difficulty: 🔴 Hard Topics: Array, Two Pointers, Binary Search, Dynamic Programming, Bit Manipulation Solution Problem Understanding We are given between 2 and 12 sorted lists. At any moment we may choose any two existing lists and merge them. If the two lists are $a$ and $b$, the merge cost is $$\operatorname{len}(a)+\operatorname{len}(b)+ \left|\operatorname{median}(a)-\operatorname{median}(b)\right|.$$ After the merge, the two lists disappear and are replaced by their sorted union. The...

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LeetCode 3698 - Split Array With Minimum Difference

LeetCode Problem 3698 Difficulty: 🟡 Medium Topics: Array, Prefix Sum Solution I can write the full detailed guide, but I need to flag one issue first: the problem statement for LeetCode 3698 - Split Array With Minimum Difference appears inconsistent with the provided Go stub and the current LeetCode catalog. Before I produce a rigorous reference-quality solution, I need to confirm the exact problem definition, because there is a high...

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LeetCode 3696 - Maximum Distance Between Unequal Words in Array I

LeetCode Problem 3696 Difficulty: 🟢 Easy Topics: Array, String Solution Problem Understanding The problem gives us an array of strings, words , and asks us to find the maximum distance between two indices i and j where the words at those positions are different . More formally, we want to find two indices such that: words[i] != words[j] i < j the value j - i + 1 is as...

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LeetCode 3692 - Majority Frequency Characters

LeetCode Problem 3692 Difficulty: 🟢 Easy Topics: Hash Table, String, Counting Solution Problem Understanding The problem asks us to analyze the frequency distribution of characters in a string and identify a particular group of characters based on how often they appear. We are given a string s containing only lowercase English letters. For every distinct character, we first count how many times it appears. Characters with the same count belong...

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LeetCode 3685 - Subsequence Sum After Capping Elements

LeetCode Problem 3685 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Dynamic Programming, Sorting Solution Here is a complete, rigorous study companion-style solution guide for LeetCode 3685 - Subsequence Sum After Capping Elements , following your requested format and voice. Problem Understanding We are given an integer array nums of size n and a positive integer k . For any integer x from 1 to n , we define the capped...

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LeetCode 3795 - Minimum Subarray Length With Distinct Sum At Least K

LeetCode Problem 3795 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sliding Window Solution LeetCode 3795: Minimum Subarray Length With Distinct Sum At Least K Problem Understanding This problem asks us to find the shortest contiguous subarray whose distinct-value sum is at least k . The important detail is that we do not sum all elements in the subarray. Instead, each distinct value contributes to the sum exactly once, regardless of...

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LeetCode 3794 - Reverse String Prefix

LeetCode Problem 3794 Difficulty: 🟢 Easy Topics: Two Pointers, String Solution LeetCode 3794 - Reverse String Prefix Problem Understanding This problem gives us a string s and an integer k . Our task is to reverse only the first k characters of the string while leaving the remaining characters unchanged. In other words, we take the substring consisting of the first k characters, reverse its order, and then append the...

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LeetCode 3765 - Complete Prime Number

LeetCode Problem 3765 Difficulty: 🟡 Medium Topics: Math, Enumeration, Number Theory Solution LeetCode 3765 - Complete Prime Number Problem Understanding The problem gives us a positive integer num and asks whether it is a Complete Prime Number . A number qualifies as a Complete Prime Number if every prefix and every suffix of its decimal representation is prime. For a number with digits d1 d2 d3 ... dn : Prefixes...

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LeetCode 3755 - Find Maximum Balanced XOR Subarray Length

LeetCode Problem 3755 Difficulty: 🟡 Medium Topics: Array, Hash Table, Bit Manipulation, Prefix Sum Solution LeetCode 3755 - Find Maximum Balanced XOR Subarray Length Problem Understanding This problem asks us to find the longest contiguous subarray that simultaneously satisfies two independent conditions: The bitwise XOR of all elements in the subarray is equal to 0 . The subarray contains an equal number of even and odd elements. We are given...

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LeetCode 3742 - Maximum Path Score in a Grid

LeetCode Problem 3742 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Matrix Solution Problem Understanding This problem presents a grid of size m x n where each cell contains a value of 0, 1, or 2. Each cell contributes both a score and a cost: a cell with value 0 adds 0 to both score and cost, a cell with value 1 adds 1 to score and 1 to cost, and...

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LeetCode 3729 - Count Distinct Subarrays Divisible by K in Sorted Array

LeetCode Problem 3729 Difficulty: 🔴 Hard Topics: Array, Hash Table, Prefix Sum Solution Problem Understanding The problem asks us to find the number of distinct subarrays in a sorted array nums such that the sum of elements in the subarray is divisible by a given integer k . A subarray is a contiguous segment of the original array, and two subarrays are considered distinct if their sequences of values differ,...

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LeetCode 3718 - Smallest Missing Multiple of K

LeetCode Problem 3718 Difficulty: 🟢 Easy Topics: Array, Hash Table Solution Problem Understanding The problem asks us to find the smallest positive multiple of k that is not present in a given integer array nums . In other words, if we consider the infinite sequence of numbers k, 2k, 3k, 4k… , we need to identify the first number in this sequence that does not appear in nums . The...

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LeetCode 3708 - Longest Fibonacci Subarray

LeetCode Problem 3708 Difficulty: 🟡 Medium Topics: Array Solution LeetCode 3708 - Longest Fibonacci Subarray Problem Understanding The problem gives us an array nums consisting of positive integers and asks us to find the length of the longest contiguous subarray that satisfies the Fibonacci property. A subarray is a contiguous segment of the original array. For a sequence to be considered Fibonacci, every element from the third position onward must...

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LeetCode 3703 - Remove K-Balanced Substrings

LeetCode Problem 3703 Difficulty: 🟡 Medium Topics: String, Stack, Simulation Solution LeetCode 3703 - Remove K-Balanced Substrings Problem Understanding We are given a string s consisting only of '(' and ')' , along with an integer k . A substring is considered k-balanced if it is exactly: "(" repeated k times + ")" repeated k times For example: k = 1 → "()" k = 2 → "(())" k =...

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LeetCode 3691 - Maximum Total Subarray Value II

LeetCode Problem 3691 Difficulty: 🔴 Hard Topics: Array, Greedy, Segment Tree, Heap (Priority Queue) Solution Problem Understanding The problem is asking us to select exactly k distinct subarrays from a given integer array nums such that the sum of their "values" is maximized. Each subarray's value is calculated as the difference between its maximum and minimum elements. Subarrays may overlap, but the exact same subarray (defined by the same start...

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LeetCode 3690 - Split and Merge Array Transformation

LeetCode Problem 3690 Difficulty: 🟡 Medium Topics: Array, Hash Table, Breadth-First Search Solution LeetCode 3690 - Split and Merge Array Transformation Problem Understanding The problem gives us two arrays, nums1 and nums2 , of equal length n . We are allowed to repeatedly perform a special operation on nums1 . In a single operation, we choose any contiguous subarray, remove it from its current location, and then insert that entire...

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LeetCode 3681 - Maximum XOR of Subsequences

LeetCode Problem 3681 Difficulty: 🔴 Hard Topics: Array, Math, Greedy, Bit Manipulation Solution LeetCode 3681 - Maximum XOR of Subsequences Problem Understanding The problem gives us an array nums of non-negative integers. We must choose two subsequences: The first subsequence has XOR value X . The second subsequence has XOR value Y . The two subsequences: May be empty. Must preserve the original order of elements, as all subsequences do....

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LeetCode 3679 - Minimum Discards to Balance Inventory

LeetCode Problem 3679 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sliding Window, Simulation, Counting Solution LeetCode 3679 - Minimum Discards to Balance Inventory Problem Understanding This problem models a stream of arriving items. On each day, exactly one item arrives, and each item has a type represented by an integer. We are given two parameters: w , the size of the sliding window. m , the maximum number of times...

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LeetCode 3661 - Maximum Walls Destroyed by Robots

LeetCode Problem 3661 Difficulty: 🔴 Hard Topics: Array, Binary Search, Dynamic Programming, Sorting Solution LeetCode 3661 - Maximum Walls Destroyed by Robots Problem Understanding This problem takes place on a one dimensional number line. We are given positions of robots and positions of walls. Every robot owns exactly one bullet, and that bullet can be fired either to the left or to the right. A robot located at position robots[i]...

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LeetCode 3654 - Minimum Sum After Divisible Sum Deletions

LeetCode Problem 3654 Difficulty: 🟡 Medium Topics: Array, Hash Table, Dynamic Programming, Prefix Sum Solution LeetCode 3654 - Minimum Sum After Divisible Sum Deletions Problem Understanding This problem gives us an array nums containing positive integers and an integer k . We may repeatedly remove any contiguous subarray whose sum is divisible by k . After each removal, the remaining elements close the gap, meaning the array becomes shorter and...

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LeetCode 3642 - Find Books with Polarized Opinions

LeetCode Problem 3642 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding The problem asks us to identify books that exhibit polarized opinions based on reading session ratings. We have two tables: books , which contains metadata about each book including its title, author, genre, and number of pages, and reading_sessions , which records individual reading sessions with a session_rating from 1 to 5. A book qualifies as having polarized opinions...

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LeetCode 3635 - Earliest Finish Time for Land and Water Rides II

LeetCode Problem 3635 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Binary Search, Greedy, Sorting Solution Great! We will cover LeetCode 3627 - Maximum Median Sum of Subsequences of Size 3 in a full, comprehensive technical guide following your formatting requirements. Problem Understanding The problem gives us an integer array nums with a length divisible by 3. We are asked to remove the array in steps by selecting any three elements...

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LeetCode 3611 - Find Overbooked Employees

LeetCode Problem 3611 Difficulty: 🟡 Medium Topics: Database Solution LeetCode 3611 - Find Overbooked Employees Problem Understanding This problem asks us to identify employees who spend an excessive amount of their working time in meetings. We are given two tables: The employees table contains employee information, including their unique identifier, name, and department. The meetings table contains meeting attendance records. Each record tells us which employee attended a meeting, on...

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LeetCode 3609 - Minimum Moves to Reach Target in Grid

LeetCode Problem 3609 Difficulty: 🔴 Hard Topics: Math Solution Problem Understanding The problem asks us to determine the minimum number of moves to reach a target point (tx, ty) from a starting point (sx, sy) on an infinite 2D grid. The movement rules are specific: from any point (x, y) , you can move either right by max(x, y) units or up by max(x, y) units. That means each move...

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LeetCode 3595 - Once Twice

LeetCode Problem 3595 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation Solution Problem Understanding The problem provides an integer array nums where every element appears exactly three times , except for one element that appears once and one element that appears twice . We are asked to identify these two unique elements and return them as a list, with the element appearing once first and the element appearing twice second. The...

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LeetCode 3593 - Minimum Increments to Equalize Leaf Paths

LeetCode Problem 3593 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Tree, Depth-First Search Solution LeetCode 3593 - Minimum Increments to Equalize Leaf Paths Problem Understanding We are given a rooted tree with root node 0 . Every node has a cost, and the score of a root-to-leaf path is the sum of the costs of all nodes along that path. We are allowed to increase the cost of any nodes...

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LeetCode 3590 - Kth Smallest Path XOR Sum

LeetCode Problem 3590 Difficulty: 🔴 Hard Topics: Array, Tree, Depth-First Search, Ordered Set Solution Problem Understanding The problem asks us to work with an undirected tree rooted at node 0, where each node has a value vals[i] and a parent par[i] . We are asked to calculate the path XOR sum for each node, which is defined as the XOR of all vals[i] along the path from the root to...

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LeetCode 3572 - Maximize Y‑Sum by Picking a Triplet of Distinct X‑Values

LeetCode Problem 3572 Difficulty: 🟡 Medium Topics: Array, Hash Table, Greedy, Sorting, Heap (Priority Queue) Solution LeetCode 3572 - Maximize Y-Sum by Picking a Triplet of Distinct X-Values Problem Understanding The problem gives us two arrays, x and y , both of length n . Each position i represents a pair (x[i], y[i]) . We need to select exactly three distinct indices i , j , and k such that...

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LeetCode 3566 - Partition Array into Two Equal Product Subsets

LeetCode Problem 3566 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation, Recursion, Enumeration Solution Here’s a detailed technical solution guide for LeetCode 3566 following your formatting rules: Problem Understanding The problem asks us to determine whether a given array of distinct positive integers can be split into two non-empty, disjoint subsets , such that the product of the elements in each subset equals a given target value . Each element of...

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LeetCode 3558 - Number of Ways to Assign Edge Weights I

LeetCode Problem 3558 Difficulty: 🟡 Medium Topics: Math, Tree, Depth-First Search Solution LeetCode 3558 - Number of Ways to Assign Edge Weights I Problem Understanding We are given an undirected tree rooted at node 1 . Every edge initially has weight 0 , and we must assign each edge a weight of either 1 or 2 . The problem asks us to choose any node x that has the maximum...

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LeetCode 3557 - Find Maximum Number of Non Intersecting Substrings

LeetCode Problem 3557 Difficulty: 🟡 Medium Topics: Hash Table, String, Dynamic Programming, Greedy Solution Problem Understanding This problem asks us to identify the maximum number of non-intersecting substrings from a given string word such that each substring is at least four characters long and starts and ends with the same character . In other words, we are scanning the string for patterns where the first and last character match and...

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LeetCode 3556 - Sum of Largest Prime Substrings

LeetCode Problem 3556 Difficulty: 🟡 Medium Topics: Hash Table, Math, String, Sorting, Number Theory Solution Problem Understanding The problem requires identifying prime numbers from all possible substrings of a given string of digits and summing the three largest unique primes. In simpler terms, given a string s of length up to 10, we must consider every contiguous sequence of digits, convert it to an integer (ignoring any leading zeros), and...

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LeetCode 3534 - Path Existence Queries in a Graph II

LeetCode Problem 3534 Difficulty: 🔴 Hard Topics: Array, Two Pointers, Binary Search, Dynamic Programming, Greedy, Bit Manipulation, Graph Theory, Sorting Solution Problem Understanding This problem asks us to compute the shortest path between nodes in an implicit undirected graph defined by a nums array and a maxDiff . Each node i corresponds to nums[i] . There is an edge between nodes i and j if the absolute difference of their...

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LeetCode 3528 - Unit Conversion I

LeetCode Problem 3528 Difficulty: 🟡 Medium Topics: Depth-First Search, Breadth-First Search, Graph Theory Solution Problem Understanding The problem is asking us to compute, for each unit type from 0 to n-1 , the number of that unit equivalent to a single unit of type 0 . We are given a list of direct conversion relationships between units. Each conversion specifies that 1 unit of sourceUnit is equivalent to some integer...

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LeetCode 3521 - Find Product Recommendation Pairs

LeetCode Problem 3521 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem asks us to identify product pairs that are frequently purchased by the same customers. The goal is to support a recommendation feature similar to "Customers who bought this also bought...", where products that commonly appear together in customer purchase histories can be suggested to future buyers. The ProductPurchases table contains one row for each (user_id, product_id) combination....

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LeetCode 3519 - Count Numbers with Non-Decreasing Digits

LeetCode Problem 3519 Difficulty: 🔴 Hard Topics: Math, String, Dynamic Programming Solution LeetCode 3519 - Count Numbers with Non-Decreasing Digits Problem Understanding We are given two very large integers l and r as decimal strings and a base b where 2 ≤ b ≤ 10 . For every integer x in the inclusive range [l, r] , we consider its representation in base b . We want to count how...

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LeetCode 3506 - Find Time Required to Eliminate Bacterial Strains

LeetCode Problem 3506 Difficulty: 🔴 Hard Topics: Array, Math, Greedy, Heap (Priority Queue) Solution Problem Understanding This problem asks us to find the minimum time required to eliminate all bacterial strains given a single initial white blood cell (WBC) and the ability of WBCs to split into two after some splitTime . Each bacterial strain has a specific time requirement timeReq[i] to be eliminated by a single WBC. The WBCs...

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LeetCode 3505 - Minimum Operations to Make Elements Within K Subarrays Equal

LeetCode Problem 3505 Difficulty: 🔴 Hard Topics: Array, Hash Table, Math, Dynamic Programming, Sliding Window, Heap (Priority Queue) Solution Problem Understanding You are given an integer array nums , and you want to create at least k non-overlapping subarrays. Every chosen subarray must have length exactly x , and after performing some modifications, every element inside each chosen subarray must become equal. The only allowed operation is increasing or decreasing...

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LeetCode 3504 - Longest Palindrome After Substring Concatenation II

LeetCode Problem 3504 Difficulty: 🔴 Hard Topics: Two Pointers, String, Dynamic Programming Solution LeetCode 3504, Longest Palindrome After Substring Concatenation II Problem Understanding We are given two strings, s and t . We may choose any substring from s and any substring from t . Either substring is allowed to be empty. After selecting them, we concatenate them in this exact order: substring_from_s + substring_from_t The resulting string must be...

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LeetCode 3482 - Analyze Organization Hierarchy

LeetCode Problem 3482 Difficulty: 🔴 Hard Topics: Database Solution LeetCode 3482 - Analyze Organization Hierarchy Problem Understanding This problem is a hierarchical organization analysis task over an employee table that forms a tree structure. Each employee has a unique employee_id , a name, a salary, and a manager_id . The employee whose manager_id is NULL is the CEO and serves as the root of the organization tree. Every other employee...

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LeetCode 3468 - Find the Number of Copy Arrays

LeetCode Problem 3468 Difficulty: 🟡 Medium Topics: Array, Math Solution LeetCode 3468 - Find the Number of Copy Arrays Problem Understanding We are given an array original and a range constraint for every position in the form of bounds[i] = [ui, vi] . We need to count how many arrays copy satisfy two conditions. The first condition states that the difference between consecutive elements in copy must be exactly the...

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LeetCode 3464 - Maximize the Distance Between Points on a Square

LeetCode Problem 3464 Difficulty: 🔴 Hard Topics: Array, Math, Binary Search, Geometry, Sorting Solution LeetCode 3464 - Maximize the Distance Between Points on a Square Problem Understanding We are given a square of side length side . Every point in the input lies somewhere on the boundary of this square. We must choose exactly k points from the given set. For any two selected points, we can compute their Manhattan...

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LeetCode 3453 - Separate Squares I

LeetCode Problem 3453 Difficulty: 🟡 Medium Topics: Array, Binary Search Solution LeetCode 3453 - Separate Squares I Problem Understanding We are given a collection of axis-aligned squares. Each square is represented by three integers: xi : x-coordinate of the bottom-left corner yi : y-coordinate of the bottom-left corner li : side length The square therefore occupies the region: $$[x_i, x_i + l_i] \times [y_i, y_i + l_i]$$ We must find...

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LeetCode 3445 - Maximum Difference Between Even and Odd Frequency II

LeetCode Problem 3445 Difficulty: 🔴 Hard Topics: String, Sliding Window, Enumeration, Prefix Sum Solution LeetCode 3445 - Maximum Difference Between Even and Odd Frequency II Problem Understanding We are given a string s consisting only of digits '0' through '4' , and an integer k . For any substring subs whose length is at least k , we may choose two characters: Character a must appear an odd number of...

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LeetCode 3419 - Minimize the Maximum Edge Weight of Graph

LeetCode Problem 3419 Difficulty: 🟡 Medium Topics: Binary Search, Depth-First Search, Breadth-First Search, Graph Theory, Shortest Path Solution Problem Understanding The problem is asking us to manipulate a directed weighted graph in order to minimize the maximum edge weight while satisfying two constraints: every node must be able to reach node 0, and no node may have more outgoing edges than a given threshold . The input consists of: n...

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LeetCode 3414 - Maximum Score of Non-overlapping Intervals

LeetCode Problem 3414 Difficulty: 🔴 Hard Topics: Array, Binary Search, Dynamic Programming, Sorting Solution Problem Understanding This problem combines weighted interval scheduling with an additional constraint: we may select at most 4 intervals, and if multiple selections achieve the same maximum total weight, we must return the lexicographically smallest list of original indices. Each interval is represented as: [left, right, weight] where: left is the starting position right is the...

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LeetCode 3412 - Find Mirror Score of a String

LeetCode Problem 3412 Difficulty: 🟡 Medium Topics: Hash Table, String, Stack, Simulation Solution LeetCode 3412 - Find Mirror Score of a String Problem Understanding We are given a lowercase English string s . Every letter has a unique "mirror" letter obtained by reversing the alphabet. For example: 'a' ↔ 'z' 'b' ↔ 'y' 'c' ↔ 'x' and so on. We process the string from left to right. For each position...

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LeetCode 3406 - Find the Lexicographically Largest String From the Box II

LeetCode Problem 3406 Difficulty: 🔴 Hard Topics: Two Pointers, String Solution LeetCode 3406 - Find the Lexicographically Largest String From the Box II Problem Understanding We are given a string word of length n and an integer numFriends . In every round, Alice splits the entire string into exactly numFriends non-empty pieces. Every possible valid split is considered exactly once. Every piece produced by every split is placed into a...

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LeetCode 3401 - Find Circular Gift Exchange Chains

LeetCode Problem 3401 Difficulty: 🔴 Hard Topics: Database Solution Here’s a full technical solution guide following your requested format for LeetCode 3401 - Find Circular Gift Exchange Chains : Problem Understanding This problem asks us to analyze a table of gift exchanges in a Secret Santa setting and identify circular chains of gift exchanges. Each row in the SecretSanta table represents a gift transaction, with giver_id as the person giving...

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LeetCode 3402 - Minimum Operations to Make Columns Strictly Increasing

LeetCode Problem 3402 Difficulty: 🟢 Easy Topics: Array, Greedy, Matrix Solution Problem Understanding The problem gives us a matrix grid of size m x n containing non-negative integers. Each column must become strictly increasing , meaning for each column j , the condition grid[i][j] < grid[i+1][j] must hold for all 0 <= i < m-1 . We are allowed to perform operations that increment any element by 1 , and...

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LeetCode 3770 - Largest Prime from Consecutive Prime Sum

LeetCode Problem 3770 Difficulty: 🟡 Medium Topics: Array, Math, Number Theory Solution LeetCode 3770 - Largest Prime from Consecutive Prime Sum Problem Understanding The problem gives us an integer n and asks us to find the largest prime number that satisfies two conditions: It is less than or equal to n . It can be written as the sum of one or more consecutive prime numbers starting from 2 ....

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LeetCode 3768 - Minimum Inversion Count in Subarrays of Fixed Length

LeetCode Problem 3768 Difficulty: 🔴 Hard Topics: Array, Segment Tree, Sliding Window Solution LeetCode 3768 - Minimum Inversion Count in Subarrays of Fixed Length Problem Understanding We are given an array nums of length n and an integer k . For every contiguous subarray of length k , we must compute its inversion count, then return the smallest inversion count among all such windows. An inversion is a pair of...

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LeetCode 3764 - Most Common Course Pairs

LeetCode Problem 3764 Difficulty: 🔴 Hard Topics: — Solution Problem Understanding The course_completions table records every course completed by every user. Each row contains the user, the course they completed, the completion date, and the rating they gave that course. The problem asks us to identify common learning pathways among strong students. A student is considered a top performer only if they satisfy two conditions: They completed at least 5...

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LeetCode 3762 - Minimum Operations to Equalize Subarrays

LeetCode Problem 3762 Difficulty: 🔴 Hard Topics: Array, Math, Binary Search, Segment Tree Solution Problem Understanding We are given an array nums and a fixed integer k . A single operation allows us to choose any element and either increase it by exactly k or decrease it by exactly k . We may perform as many operations as needed. For each query [l, r] , we only consider the subarray...

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LeetCode 3760 - Maximum Substrings With Distinct Start

LeetCode Problem 3760 Difficulty: 🟡 Medium Topics: Hash Table, String Solution LeetCode 3760 - Maximum Substrings With Distinct Start Problem Understanding The problem asks us to split a string into as many non-empty substrings as possible, with one important restriction: the first character of every substring must be different from the first character of every other substring. In other words, if we divide the string into several contiguous pieces, and...

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LeetCode 3751 - Total Waviness of Numbers in Range I

LeetCode Problem 3751 Difficulty: 🟡 Medium Topics: Math, Dynamic Programming, Enumeration Solution LeetCode 3751 - Total Waviness of Numbers in Range I Problem Understanding This problem asks us to compute the total waviness of every integer in an inclusive range [num1, num2] . For a single number, waviness is defined as the number of digits that are either peaks or valleys. A digit is a peak if it is strictly...

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LeetCode 3748 - Count Stable Subarrays

LeetCode Problem 3748 Difficulty: 🔴 Hard Topics: Array, Binary Search, Prefix Sum Solution Problem Understanding The problem asks us to count "stable" subarrays within a given array nums . A subarray is stable if it contains no inversions , which means that for any two indices i < j in the subarray, nums[i] <= nums[j] . Essentially, a stable subarray is non-decreasing . We are given multiple queries [li, ri]...

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LeetCode 3745 - Maximize Expression of Three Elements

LeetCode Problem 3745 Difficulty: 🟢 Easy Topics: Array, Greedy, Sorting, Enumeration Solution LeetCode 3745 - Maximize Expression of Three Elements Problem Understanding The problem gives us an integer array nums and asks us to choose three elements a , b , and c from distinct indices such that the expression: $$a + b - c$$ is as large as possible. The important detail is that the three elements must come...

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LeetCode 3744 - Find Kth Character in Expanded String

LeetCode Problem 3744 Difficulty: 🟡 Medium Topics: String Solution LeetCode 3744 - Find Kth Character in Expanded String Problem Understanding The problem gives us a string s containing one or more lowercase words separated by single spaces. From this original string, we conceptually build a new string t using a special expansion rule. For each word, the first character appears once, the second character appears twice, the third character appears...

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LeetCode 3743 - Maximize Cyclic Partition Score

LeetCode Problem 3743 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming Solution Problem Understanding We are given a cyclic array nums , which means the array is considered to wrap around from the last element back to the first element. We want to partition the entire cycle into at most k contiguous subarrays. Since the array is cyclic, one of the subarrays is allowed to cross the boundary between the last...

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LeetCode 3734 - Lexicographically Smallest Palindromic Permutation Greater Than Target

LeetCode Problem 3734 Difficulty: 🔴 Hard Topics: Two Pointers, String, Enumeration Solution Problem Understanding We are given two strings, s and target , of the same length n . The goal is to rearrange the characters of s into a palindrome and then choose, among all possible palindromic permutations, the lexicographically smallest one that is strictly greater than target . A string a is lexicographically greater than a string b...

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LeetCode 3727 - Maximum Alternating Sum of Squares

LeetCode Problem 3727 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting Solution LeetCode 3727 - Maximum Alternating Sum of Squares Problem Understanding We are given an integer array nums , and we are allowed to rearrange its elements in any order before computing a score. The score of a rearranged array arr is defined as: $$arr[0]^2 - arr[1]^2 + arr[2]^2 - arr[3]^2 + \cdots$$ The sign alternates between positive and negative...

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LeetCode 3726 - Remove Zeros in Decimal Representation

LeetCode Problem 3726 Difficulty: 🟢 Easy Topics: Math, Simulation Solution LeetCode 3726 - Remove Zeros in Decimal Representation Problem Understanding The problem gives us a positive integer n and asks us to remove every digit '0' from its decimal representation. After all zero digits have been removed, we must return the resulting value as an integer. In other words, we first view the number as a sequence of decimal digits....

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LeetCode 3723 - Maximize Sum of Squares of Digits

LeetCode Problem 3723 Difficulty: 🟡 Medium Topics: Math, Greedy Solution Problem Understanding The problem asks us to construct a positive integer n of exactly num digits such that the sum of its digits equals sum . Among all possible integers that satisfy these conditions (called good integers ), we must return the integer that maximizes the sum of the squares of its digits , which is called the score ....

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LeetCode 3716 - Find Churn Risk Customers

LeetCode Problem 3716 Difficulty: 🟡 Medium Topics: — Solution Find Churn Risk Customers Problem Understanding This problem asks us to identify subscribers who appear likely to churn based on their subscription history. The data is stored in the subscription_events table, where each row represents a subscription-related action performed by a user. Each event records the subscription state after that action. A user may start a subscription, upgrade to a more...

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LeetCode 3715 - Sum of Perfect Square Ancestors

LeetCode Problem 3715 Difficulty: 🔴 Hard Topics: Array, Hash Table, Math, Tree, Depth-First Search, Counting, Number Theory Solution Problem Understanding This problem asks us to compute a sum across all non-root nodes in a tree based on ancestor relationships and the property of perfect squares. We are given a rooted tree of n nodes, represented as an edge list. Each node has a positive integer value from the nums array....

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LeetCode 3707 - Equal Score Substrings

LeetCode Problem 3707 Difficulty: 🟢 Easy Topics: String, Prefix Sum Solution Problem Understanding The problem asks us to determine if a given string s can be split into two non-empty substrings such that the sum of the alphabetic positions of characters in the left substring is equal to the sum in the right substring. Each character 'a' to 'z' maps to values 1 through 26 respectively. The input is a...

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LeetCode 3706 - Maximum Distance Between Unequal Words in Array II

LeetCode Problem 3706 Difficulty: 🟡 Medium Topics: Array, String Solution LeetCode 3706 - Maximum Distance Between Unequal Words in Array II Problem Understanding We are given an array of strings called words . Our goal is to find two different indices i and j such that the strings at those positions are different, meaning words[i] != words[j] . For every valid pair, the distance is defined as: $$j - i...

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LeetCode 3705 - Find Golden Hour Customers

LeetCode Problem 3705 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding This problem asks us to identify "golden hour customers" from a restaurant's order history. A golden hour customer is defined as someone who consistently orders during peak hours and maintains high satisfaction. Specifically, a customer must meet all of the following conditions: they must have made at least three orders, at least 60% of their orders must fall within...

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LeetCode 3697 - Compute Decimal Representation

LeetCode Problem 3697 Difficulty: 🟢 Easy Topics: Array, Math Solution Problem Understanding This problem asks us to decompose a positive integer n into the fewest possible base-10 components , where a base-10 component is defined as a single digit (1-9) multiplied by a power of 10. Essentially, we are breaking n down into its decimal place contributions . For example, for n = 537 , the hundreds place contributes 500,...

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LeetCode 3695 - Maximize Alternating Sum Using Swaps

LeetCode Problem 3695 Difficulty: 🔴 Hard Topics: Array, Greedy, Union-Find, Sorting Solution LeetCode 3695 - Maximize Alternating Sum Using Swaps Problem Understanding We are given an array nums and a list of allowed swap operations. The alternating sum of an array is defined as: $$nums[0] - nums[1] + nums[2] - nums[3] + \cdots$$ Elements at even indices contribute positively, while elements at odd indices contribute negatively. The important detail is...

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LeetCode 3693 - Climbing Stairs II

LeetCode Problem 3693 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding This problem is an extension of the classic "climbing stairs" dynamic programming problem but with more complex jump costs. You are given a staircase with n + 1 steps, numbered from 0 to n . Each intermediate step i (1-indexed) has an associated cost costs[i] . You start at step 0 with zero cost. From any step...

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LeetCode 3694 - Distinct Points Reachable After Substring Removal

LeetCode Problem 3694 Difficulty: 🟡 Medium Topics: Hash Table, String, Sliding Window, Prefix Sum Solution LeetCode 3694 - Distinct Points Reachable After Substring Removal Problem Understanding We are given a movement string s consisting of the four directions: U increases the y-coordinate by 1. D decreases the y-coordinate by 1. L decreases the x-coordinate by 1. R increases the x-coordinate by 1. Starting from (0, 0) , the entire string...

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LeetCode 3689 - Maximum Total Subarray Value I

LeetCode Problem 3689 Difficulty: 🟡 Medium Topics: Array, Greedy Solution Problem Understanding The problem asks us to select exactly k non-empty subarrays from a given integer array nums , where subarrays may overlap and can even be identical. For each chosen subarray nums[l..r] , we compute its value as the difference between its maximum and minimum element, specifically max(nums[l..r]) - min(nums[l..r]) . The goal is to maximize the total sum...

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LeetCode 3686 - Number of Stable Subsequences

LeetCode Problem 3686 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming Solution Problem Understanding The problem asks us to count how many subsequences of a given integer array are stable , where stability is defined by a constraint on parity patterns inside the subsequence itself. A subsequence is formed by deleting zero or more elements without changing the relative order of the remaining elements. A subsequence is considered unstable if, when...

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LeetCode 3688 - Bitwise OR of Even Numbers in an Array

LeetCode Problem 3688 Difficulty: 🟢 Easy Topics: Array, Bit Manipulation, Simulation Solution Problem Understanding This problem asks us to compute the bitwise OR of all even numbers in a given integer array nums . A number is considered even if it is divisible by 2, meaning its least significant bit is 0. The task is to iterate through the array, select only the even numbers, and combine them using the...

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LeetCode 3683 - Earliest Time to Finish One Task

LeetCode Problem 3683 Difficulty: 🟢 Easy Topics: Array Solution LeetCode 3683 - Earliest Time to Finish One Task Problem Understanding The problem gives us a list of tasks, where each task is represented by two integers: si , the time when the task starts. ti , the amount of time required to complete the task. A task finishes at time: $$\text{finishTime} = s_i + t_i$$ Our goal is to determine...

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LeetCode 3684 - Maximize Sum of At Most K Distinct Elements

LeetCode Problem 3684 Difficulty: 🟢 Easy Topics: Array, Hash Table, Greedy, Sorting Solution Problem Understanding This problem requires selecting at most k distinct elements from a given array of positive integers nums such that their sum is maximized. The result must be returned as a list sorted in strictly descending order . The input nums represents a collection of numbers from which we can pick a subset. Each number can...

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LeetCode 3677 - Count Binary Palindromic Numbers

LeetCode Problem 3677 Difficulty: 🔴 Hard Topics: Math, Bit Manipulation Solution Problem Understanding We are given a non-negative integer n and asked to count how many integers k in the range [0, n] have a binary representation that is a palindrome when written without leading zeros. A binary palindrome means that if you take the binary string of a number and read it from left to right or right to...

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LeetCode 3682 - Minimum Index Sum of Common Elements

LeetCode Problem 3682 Difficulty: 🟡 Medium Topics: Array, Hash Table Solution Problem Understanding This problem is asking us to identify the smallest sum of indices from two equal-length arrays, nums1 and nums2 , such that the elements at those indices are equal. Formally, we want a pair (i, j) where nums1[i] == nums2[j] , and we want the minimum value of i + j . If no such pair exists,...

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LeetCode 3680 - Generate Schedule

LeetCode Problem 3680 Difficulty: 🟡 Medium Topics: Array, Math, Greedy Solution Problem Understanding The problem is asking us to generate a round-robin style schedule for n teams, where each team plays every other team exactly twice, once at home and once away. Each day in the schedule can host exactly one match, and a team is not allowed to play on consecutive days. The input is simply an integer n...

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LeetCode 3676 - Count Bowl Subarrays

LeetCode Problem 3676 Difficulty: 🟡 Medium Topics: Array, Stack, Monotonic Stack Solution Problem Understanding The problem asks us to count how many subarrays in an array of distinct integers satisfy a specific “bowl” condition. A subarray nums[l...r] is considered a bowl if it has length at least 3 and the smaller of its two endpoints is strictly greater than the maximum value of all elements strictly inside the subarray. In...

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LeetCode 3674 - Minimum Operations to Equalize Array

LeetCode Problem 3674 Difficulty: 🟢 Easy Topics: Array, Bit Manipulation, Brainteaser Solution Let's go step by step and produce a fully detailed, reference-style solution guide for LeetCode 3674 following your requested formatting. Problem Understanding The problem asks us to make all elements of an integer array nums equal using the minimum number of operations. Each operation consists of selecting a contiguous subarray and replacing every element in that subarray with...

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LeetCode 3667 - Sort Array By Absolute Value

LeetCode Problem 3667 Difficulty: 🟢 Easy Topics: Array, Math, Two Pointers, Sorting Solution Problem Understanding The problem asks us to reorder an integer array such that the elements are sorted in non-decreasing order of their absolute values . This means we are not sorting based on the actual numeric value, but rather based on how far each number is from zero on the number line, regardless of sign. In simpler...

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LeetCode 3668 - Restore Finishing Order

LeetCode Problem 3668 Difficulty: 🟢 Easy Topics: Array, Hash Table Solution LeetCode 3668 - Restore Finishing Order Problem Understanding This problem gives us two arrays: order , which represents the finishing order of all participants in a race. friends , which contains the IDs of our friends. The array order is a permutation of the integers from 1 to n , meaning every participant appears exactly once. The position of...

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LeetCode 3665 - Twisted Mirror Path Count

LeetCode Problem 3665 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Matrix Solution Problem Understanding This problem asks us to count all unique paths from the top-left corner (0, 0) to the bottom-right corner (m - 1, n - 1) of a binary grid where certain cells contain mirrors. The robot can move only right or down , but mirrors change its trajectory in a very specific way: moving right into...

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LeetCode 3664 - Two-Letter Card Game

LeetCode Problem 3664 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Counting, Enumeration Solution Problem Understanding Each card consists of exactly two lowercase letters. A card is only relevant if it contains the given letter x somewhere in its two positions. During the game, we repeatedly select two cards that satisfy two conditions: Both cards contain the letter x . The two strings differ in exactly one position. After selecting...

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LeetCode 3662 - Filter Characters by Frequency

LeetCode Problem 3662 Difficulty: 🟢 Easy Topics: Hash Table, String, Counting Solution Problem Understanding This problem asks us to filter a string based on character frequency while preserving the original order of characters. We are given a string s consisting only of lowercase English letters and an integer k . The goal is to construct a new string by keeping only those characters whose total frequency in the entire string...

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LeetCode 3663 - Find The Least Frequent Digit

LeetCode Problem 3663 Difficulty: 🟢 Easy Topics: Array, Hash Table, Math, Counting Solution Problem Understanding The problem asks us to find the least frequent digit in the decimal representation of a given integer n . In other words, we need to count how many times each digit from 0 to 9 appears in the number, and then return the smallest digit that occurs the fewest times. The input is a...

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LeetCode 3658 - GCD of Odd and Even Sums

LeetCode Problem 3658 Difficulty: 🟢 Easy Topics: Math, Number Theory Solution Problem Understanding The problem asks us to calculate the greatest common divisor (GCD) of two specific sums derived from an integer input n . The first sum, sumOdd , is the sum of the first n positive odd numbers, and the second sum, sumEven , is the sum of the first n positive even numbers. The input n is...

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LeetCode 3657 - Find Loyal Customers

LeetCode Problem 3657 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding This problem is a SQL aggregation and filtering task. We are given a table named customer_transactions that contains every transaction performed by customers. Each row represents either a purchase or a refund. A customer is considered loyal only if all three conditions are satisfied: They have made at least 3 purchase transactions. Their activity spans at least 30 days....

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LeetCode 3651 - Minimum Cost Path with Teleportations

LeetCode Problem 3651 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Matrix Solution Problem Understanding The problem asks us to find the minimum cost to travel from the top-left corner (0, 0) of a 2D grid to the bottom-right corner (m - 1, n - 1) . Each cell contains a non-negative integer representing its cost. There are two ways to move: Normal move : move either right or down, paying...

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LeetCode 3655 - XOR After Range Multiplication Queries II

LeetCode Problem 3655 Difficulty: 🔴 Hard Topics: Array, Divide and Conquer Solution Problem Understanding We are given an array nums and a list of queries. Each query has the form: [li, ri, ki, vi] For a query, we start at index li and repeatedly jump forward by ki until we pass ri . Every visited position is multiplied by vi , and the result is taken modulo 10^9 + 7...

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LeetCode 3653 - XOR After Range Multiplication Queries I

LeetCode Problem 3653 Difficulty: 🟡 Medium Topics: Array, Divide and Conquer, Simulation Solution LeetCode 3653 - XOR After Range Multiplication Queries I Problem Understanding We are given an integer array nums and a list of queries. Each query has the form: [li, ri, ki, vi] For a query, we start at index li and repeatedly move forward by ki positions until we exceed ri . Every visited index is updated...

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LeetCode 3652 - Best Time to Buy and Sell Stock using Strategy

LeetCode Problem 3652 Difficulty: 🟡 Medium Topics: Array, Sliding Window, Prefix Sum Solution Problem Understanding This problem asks us to calculate the maximum possible profit from a stock trading strategy with the option to modify it once in a very specific way. You are given two arrays: prices , which contains the stock price on each day, and strategy , which tells you what action to take each day: -1...

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LeetCode 3647 - Maximum Weight in Two Bags

LeetCode Problem 3647 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding This problem asks us to distribute a set of items, each with a given weight, into two separate bags with fixed capacity limits, in order to maximize the total weight placed across both bags. Each item in the input array weights can be used at most once, and for each item we must decide one of three...

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LeetCode 3648 - Minimum Sensors to Cover Grid

LeetCode Problem 3648 Difficulty: 🟡 Medium Topics: Math Solution Problem Understanding The problem gives an n × m grid where each cell is identified by coordinates (r, c) . A sensor can be placed on any cell, and its coverage is defined using Chebyshev distance. Specifically, a sensor at (r, c) covers every cell (r2, c2) such that max(|r - r2|, |c - c2|) ≤ k . This means each...

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LeetCode 3646 - Next Special Palindrome Number

LeetCode Problem 3646 Difficulty: 🔴 Hard Topics: Backtracking, Bit Manipulation Solution Problem Understanding This problem asks us to construct a number system under two simultaneous constraints and then perform a “next greater element” query over that constrained set. We are given an integer n , and we must find the smallest integer strictly greater than n such that the number satisfies a special structural property. A number is considered special...

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LeetCode 3640 - Trionic Array II

LeetCode Problem 3640 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming Solution Problem Understanding We are given an integer array nums , and we must find the maximum possible sum of a contiguous subarray that follows a very specific shape: It first increases strictly. Then decreases strictly. Then increases strictly again. More formally, for a subarray nums[l...r] , there must exist indices: l < p < q < r such that:...

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LeetCode 3643 - Flip Square Submatrix Vertically

LeetCode Problem 3643 Difficulty: 🟢 Easy Topics: Array, Two Pointers, Matrix Solution LeetCode 3643 - Flip Square Submatrix Vertically Problem Understanding This problem gives us an m x n matrix called grid and three integers: x , y , and k . The values x and y specify the top-left corner of a square submatrix, while k specifies the side length of that square. Therefore, the submatrix occupies: Problem Understanding...

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LeetCode 3641 - Longest Semi-Repeating Subarray

LeetCode Problem 3641 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sliding Window Solution LeetCode 3641 - Longest Semi-Repeating Subarray Problem Understanding We are given an integer array nums and an integer k . A subarray is considered semi-repeating if the number of distinct values that appear more than once inside that subarray is at most k . To understand this carefully, consider a frequency map for a subarray: If a...

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LeetCode 3636 - Threshold Majority Queries

LeetCode Problem 3636 Difficulty: 🔴 Hard Topics: Array, Hash Table, Binary Search, Divide and Conquer, Counting, Prefix Sum Solution Problem Understanding The problem asks us to process multiple queries on a given array nums where each query specifies a subarray defined by [li, ri] and a threshold . For each query, we need to find an element in the subarray that appears at least threshold times. If multiple elements meet...

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LeetCode 3638 - Maximum Balanced Shipments

LeetCode Problem 3638 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Stack, Greedy, Monotonic Stack Solution Problem Understanding We are given an array weight representing parcels arranged in a line. We must partition some prefix-suffix segments of this array into a collection of non-overlapping contiguous subarrays called shipments. Each parcel can belong to at most one shipment, and it is also allowed to leave some parcels unused. A shipment is considered...

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LeetCode 3632 - Subarrays with XOR at Least K

LeetCode Problem 3632 Difficulty: 🔴 Hard Topics: Array, Bit Manipulation, Trie, Prefix Sum Solution Problem Understanding This problem asks us to count the number of contiguous subarrays of a given array nums such that the bitwise XOR of all elements in the subarray is greater than or equal to a given integer k . The input array nums consists of positive integers, and k is a non-negative integer. A contiguous...

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LeetCode 3630 - Partition Array for Maximum XOR and AND

LeetCode Problem 3630 Difficulty: 🔴 Hard Topics: Array, Math, Greedy, Bit Manipulation, Enumeration Solution Problem Understanding The problem asks us to partition an integer array nums into three subsequences A , B , and C such that every element belongs to exactly one subsequence. The goal is to maximize the sum XOR(A) + AND(B) + XOR(C) , where XOR and AND represent the bitwise XOR and AND of the elements...

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LeetCode 3625 - Count Number of Trapezoids II

LeetCode Problem 3625 Difficulty: 🔴 Hard Topics: Array, Hash Table, Math, Geometry Solution Problem Understanding The problem asks us to count the number of unique trapezoids that can be formed from a set of points on a 2D Cartesian plane. Each point is given as a pair of integers representing its x and y coordinates. A trapezoid is defined as a convex quadrilateral with at least one pair of parallel...

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LeetCode 3626 - Find Stores with Inventory Imbalance

LeetCode Problem 3626 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding This problem asks us to identify stores with an inventory imbalance . Specifically, for each store, we need to compare the quantity of the most expensive product against the quantity of the cheapest product . A store is considered imbalanced if the most expensive product has fewer units in stock than the cheapest product. Additionally, we need to calculate...

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LeetCode 3620 - Network Recovery Pathways

LeetCode Problem 3620 Difficulty: 🔴 Hard Topics: Array, Binary Search, Dynamic Programming, Graph Theory, Topological Sort, Heap (Priority Queue), Shortest Path Solution LeetCode 3620 - Network Recovery Pathways Problem Understanding We are given a directed acyclic graph (DAG) with n nodes numbered from 0 to n - 1 . Each directed edge is represented as: u -> v with cost c and stored in: edges[i] = [u, v, c] We...

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LeetCode 3617 - Find Students with Study Spiral Pattern

LeetCode Problem 3617 Difficulty: 🔴 Hard Topics: — Solution Problem Understanding The task asks us to identify students who exhibit a very specific behavioral pattern in their study history, called a Study Spiral Pattern. We are given two relational tables: one describing students and another describing their study sessions over time. Each study session includes the subject studied, the date, and the number of hours spent. The goal is to...

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LeetCode 3622 - Check Divisibility by Digit Sum and Product

LeetCode Problem 3622 Difficulty: 🟢 Easy Topics: Math Solution Problem Understanding The problem asks us to determine if a given positive integer n is divisible by the sum of two specific quantities derived from its digits: the digit sum and the digit product . The digit sum is obtained by adding all the digits of n , and the digit product is obtained by multiplying all the digits of n...

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LeetCode 3612 - Process String with Special Operations I

LeetCode Problem 3612 Difficulty: 🟡 Medium Topics: String, Simulation Solution Problem Understanding The problem asks us to simulate the construction of a string called result by processing an input string s from left to right. The input string contains lowercase English letters and three special operators: * , # , and % . Each character in the input modifies the evolving result string in a specific way. A lowercase letter...

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LeetCode 3619 - Count Islands With Total Value Divisible by K

LeetCode Problem 3619 Difficulty: 🟡 Medium Topics: Array, Depth-First Search, Breadth-First Search, Union-Find, Matrix Solution Problem Understanding The problem is asking us to count islands in a 2D grid where the sum of the values in each island is divisible by a given integer k . An island is defined as a group of positive integers that are 4-directionally connected, meaning we can move horizontally or vertically between adjacent positive...

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LeetCode 3618 - Split Array by Prime Indices

LeetCode Problem 3618 Difficulty: 🟡 Medium Topics: Array, Math, Number Theory Solution LeetCode 3618 - Split Array by Prime Indices Problem Understanding The problem gives us an integer array nums and asks us to divide its elements into two groups based on their indices. Array A contains all elements whose indices are prime numbers. Array B contains all remaining elements, meaning indices that are not prime. Remember that array indices...

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LeetCode 3614 - Process String with Special Operations II

LeetCode Problem 3614 Difficulty: 🔴 Hard Topics: String, Simulation Solution Problem Understanding The problem defines a transformation process over a string s that contains lowercase letters and three special operation characters: '*' , '#' , and '%' . We process the string from left to right, maintaining a dynamically changing result string. Each lowercase letter is appended to the result. The '*' operation deletes the last character of the result...

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LeetCode 3605 - Minimum Stability Factor of Array

LeetCode Problem 3605 Difficulty: 🔴 Hard Topics: Array, Math, Binary Search, Greedy, Segment Tree, Number Theory Solution LeetCode 3605 - Minimum Stability Factor of Array Problem Understanding We are given an array nums and an integer maxC . A subarray is called stable if the greatest common divisor (HCF/GCD) of all elements in that subarray is at least 2 . The stability factor of the entire array is defined as...

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LeetCode 3606 - Coupon Code Validator

LeetCode Problem 3606 Difficulty: 🟢 Easy Topics: Array, Hash Table, String, Sorting Solution Problem Understanding The problem is asking us to validate a set of coupons based on three criteria: the coupon code must be a non-empty string containing only alphanumeric characters or underscores, the business line must belong to a set of four predefined categories, and the coupon must be active. We are given three arrays of equal length,...

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LeetCode 3604 - Minimum Time to Reach Destination in Directed Graph

LeetCode Problem 3604 Difficulty: 🟡 Medium Topics: Graph Theory, Heap (Priority Queue), Shortest Path Solution Problem Understanding This problem asks us to compute the minimum time required to reach the last node in a directed graph where each edge has a time window constraint. You start at node 0 at time 0 , and each edge [u, v, start, end] can only be used if you traverse it at an...

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LeetCode 3607 - Power Grid Maintenance

LeetCode Problem 3607 Difficulty: 🟡 Medium Topics: Array, Hash Table, Depth-First Search, Breadth-First Search, Union-Find, Graph Theory, Heap (Priority Queue), Ordered Set Solution Problem Understanding The problem gives an undirected graph of c power stations labeled from 1 to c , connected by bidirectional cables. These connections define connected components, which are referred to as power grids. Importantly, these grids are static, meaning connectivity does not change even if stations...

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LeetCode 3599 - Partition Array to Minimize XOR

LeetCode Problem 3599 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Bit Manipulation, Prefix Sum Solution Problem Understanding This problem asks us to partition an array of integers, nums , into exactly k non-empty contiguous subarrays, and then compute the bitwise XOR of each subarray. The goal is to minimize the maximum XOR among these subarrays. Essentially, we are trying to distribute the elements into k groups such that the "largest...

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LeetCode 3594 - Minimum Time to Transport All Individuals

LeetCode Problem 3594 Difficulty: 🔴 Hard Topics: Array, Bit Manipulation, Graph Theory, Heap (Priority Queue), Shortest Path, Bitmask Solution Problem Understanding This problem is a shortest-path optimization over a highly constrained state space where you are repeatedly moving groups of people across a river using a single boat. The twist is that the travel time is not fixed: it depends both on the slowest person in the group and on...

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LeetCode 3597 - Partition String

LeetCode Problem 3597 Difficulty: 🟡 Medium Topics: Hash Table, String, Trie, Simulation Solution LeetCode 3597 - Partition String Problem Understanding We are given a string s and must partition it into segments according to a very specific process. We start at the current position in the string and begin building a segment character by character. As we extend the segment, we continuously check whether that exact segment has already appeared...

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LeetCode 3415 - Find Products with Three Consecutive Digits

LeetCode Problem 3415 Difficulty: 🟢 Easy Topics: Database Solution Problem Understanding This is a SQL database problem involving pattern matching on strings. We are given a table named Products with two columns: Column Description product_id Unique identifier for each product name Product name string The goal is to return all products whose names contain a sequence of exactly three consecutive digits . The important detail is the word exactly ....

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LeetCode 3596 - Minimum Cost Path with Alternating Directions I

LeetCode Problem 3596 Difficulty: 🟡 Medium Topics: Math, Brainteaser Solution Problem Understanding This problem requires computing the minimum total cost to traverse a grid from the top-left corner (0, 0) to the bottom-right corner (m - 1, n - 1) while following a strict alternating movement pattern. Each cell (i, j) has a cost to enter, calculated as (i + 1) * (j + 1) . Movement is constrained by...

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LeetCode 3592 - Inverse Coin Change

LeetCode Problem 3592 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding The problem gives us a 1-indexed array numWays , where numWays[i] indicates the number of ways to form a total amount i using an infinite supply of some unknown coin denominations . The goal is to recover the original set of coin denominations. The array effectively represents the output of a classical coin change problem, but in...

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LeetCode 3591 - Check if Any Element Has Prime Frequency

LeetCode Problem 3591 Difficulty: 🟢 Easy Topics: Array, Hash Table, Math, Counting, Number Theory Solution Problem Understanding This problem asks us to determine whether any number in an array appears a prime number of times. In other words, for each unique number in the input array nums , we calculate its frequency-the number of occurrences-and check if that frequency is a prime number. If at least one element has a...

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LeetCode 3589 - Count Prime-Gap Balanced Subarrays

LeetCode Problem 3589 Difficulty: 🟡 Medium Topics: Array, Math, Queue, Sliding Window, Number Theory, Monotonic Queue Solution Count Prime-Gap Balanced Subarrays Problem Understanding We are given an integer array nums and an integer k . We must count how many contiguous subarrays satisfy two conditions: The subarray contains at least two prime numbers. Among all prime numbers inside that subarray, the difference between the largest prime and the smallest prime...

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LeetCode 3586 - Find COVID Recovery Patients

LeetCode Problem 3586 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The task is to identify patients who have recovered from COVID based on their testing history. We are given two tables: one containing patient demographic information and another containing COVID test records with timestamps and results. A patient is considered recovered if they have at least one positive test and, after that positive test, they later have at least...

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LeetCode 3585 - Find Weighted Median Node in Tree

LeetCode Problem 3585 Difficulty: 🔴 Hard Topics: Array, Binary Search, Dynamic Programming, Bit Manipulation, Tree, Depth-First Search Solution Problem Understanding We are given a weighted tree with n nodes. A tree is an undirected connected graph with exactly n - 1 edges, which guarantees that there is exactly one simple path between any two nodes. Each edge has a positive weight. For every query [u, v] , we look at...

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LeetCode 3588 - Find Maximum Area of a Triangle

LeetCode Problem 3588 Difficulty: 🟡 Medium Topics: Array, Hash Table, Math, Greedy, Geometry, Enumeration Solution LeetCode 3588 - Find Maximum Area of a Triangle Problem Understanding We are given n distinct points on a 2D Cartesian plane. Each point is represented as [x, y] . We must choose any three points that form a non-degenerate triangle, meaning the area must be strictly greater than zero. Among all valid triangles, we...

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LeetCode 3582 - Generate Tag for Video Caption

LeetCode Problem 3582 Difficulty: 🟢 Easy Topics: String, Simulation Solution Problem Understanding The problem asks us to transform a given caption string into a valid video tag following a strict sequence of rules. The input is a single string caption consisting only of English letters and spaces. These words must be transformed into a single hashtag-style identifier. The transformation has three ordered steps. First, we must merge all words into...

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LeetCode 3580 - Find Consistently Improving Employees

LeetCode Problem 3580 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The task asks us to identify employees whose performance has consistently improved over their most recent three performance reviews. Each employee may have multiple reviews stored in the performance_reviews table, and we must focus only on the last three reviews per employee when ordered by review_date . For each employee, we first determine whether they have at least three...

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LeetCode 3579 - Minimum Steps to Convert String with Operations

LeetCode Problem 3579 Difficulty: 🔴 Hard Topics: String, Dynamic Programming Solution Problem Understanding The problem asks us to transform one string, word1 , into another string, word2 , using the minimum number of operations. Both strings have equal length and consist only of lowercase English letters. The allowed operations are applied on contiguous substrings of word1 and include replacing a character, swapping two characters, or reversing the entire substring. Each...

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LeetCode 3578 - Count Partitions With Max-Min Difference at Most K

LeetCode Problem 3578 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Queue, Sliding Window, Prefix Sum, Monotonic Queue Solution LeetCode 3578 - Count Partitions With Max-Min Difference at Most K Problem Understanding We are given an array nums and an integer k . We want to split the array into one or more contiguous, non-empty segments. Every element must belong to exactly one segment, and the segments must preserve the original...

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LeetCode 3577 - Count the Number of Computer Unlocking Permutations

LeetCode Problem 3577 Difficulty: 🟡 Medium Topics: Array, Math, Brainteaser, Combinatorics Solution Problem Understanding The problem presents a set of n computers, each with a unique password complexity represented in an array complexity of length n . The computers are labeled 0 to n - 1 , and only computer 0 is initially unlocked. To unlock another computer i , you must already have unlocked at least one computer j...

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LeetCode 3573 - Best Time to Buy and Sell Stock V

LeetCode Problem 3573 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution LeetCode 3573 - Best Time to Buy and Sell Stock V Problem Understanding This problem extends the classic stock trading dynamic programming family by allowing two different kinds of transactions. A normal transaction consists of buying first and selling later. If the stock price rises, the profit is: $$\text{sell price} - \text{buy price}$$ A short selling transaction reverses the...

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LeetCode 3574 - Maximize Subarray GCD Score

LeetCode Problem 3574 Difficulty: 🔴 Hard Topics: Array, Math, Enumeration, Number Theory Solution Problem Understanding The problem asks us to choose a contiguous subarray from an array of positive integers after performing at most k doubling operations, where each element can be doubled at most once. After applying these optional doublings, we compute the score of a subarray as the product of its length and the greatest common divisor (GCD)...

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LeetCode 3571 - Find the Shortest Superstring II

LeetCode Problem 3571 Difficulty: 🟢 Easy Topics: String Solution Problem Understanding This problem asks us to construct the shortest string that contains two given strings, s1 and s2 , as substrings. In other words, we are asked to merge s1 and s2 in such a way that no unnecessary characters are added, but both strings appear contiguously somewhere in the resulting string. The inputs, s1 and s2 , are both...

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LeetCode 3570 - Find Books with No Available Copies

LeetCode Problem 3570 Difficulty: 🟢 Easy Topics: Database Solution Problem Understanding This problem asks us to identify books in a library system that are both fully unavailable for borrowing and currently have active borrowers who have not returned them yet. We are given two tables. The library_books table contains static information about each book, including how many total physical copies exist in the library. The borrowing_records table captures individual borrow...

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LeetCode 3567 - Minimum Absolute Difference in Sliding Submatrix

LeetCode Problem 3567 Difficulty: 🟡 Medium Topics: Array, Sorting, Matrix Solution Problem Understanding The problem requires computing a specific statistic for every contiguous k x k submatrix of a given m x n integer matrix grid . For each submatrix, we must find the minimum absolute difference between any two distinct elements. The final result is a 2D array ans of size (m - k + 1) x (n -...

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LeetCode 3560 - Find Minimum Log Transportation Cost

LeetCode Problem 3560 Difficulty: 🟢 Easy Topics: Math Solution Problem Understanding The problem asks us to transport two logs of lengths n and m using three trucks, where each truck can carry a log of length at most k . If a log is longer than k , it must be cut into smaller pieces. Cutting a log of length x into two pieces of lengths len1 and len2 incurs...

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LeetCode 3565 - Sequential Grid Path Cover

LeetCode Problem 3565 Difficulty: 🟡 Medium Topics: Array, Recursion, Matrix Solution Problem Understanding The problem asks us to find a path that visits every cell of a given m x n grid exactly once while visiting certain numbered cells in a specified order. Specifically, the grid contains integers from 1 to k in exactly one cell each, and the rest of the cells are zeros. The path can start at...

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LeetCode 3563 - Lexicographically Smallest String After Adjacent Removals

LeetCode Problem 3563 Difficulty: 🔴 Hard Topics: String, Dynamic Programming Solution Problem Understanding The problem asks us to find the lexicographically smallest string that can be formed by repeatedly removing adjacent pairs of characters in a string s that are consecutive in the alphabet. Consecutive letters can be in either order (e.g., 'a' followed by 'b' or 'b' followed by 'a' ) and the alphabet is considered circular, meaning 'a'...

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LeetCode 3561 - Resulting String After Adjacent Removals

LeetCode Problem 3561 Difficulty: 🟡 Medium Topics: String, Stack, Simulation Solution Problem Understanding The problem asks us to repeatedly remove pairs of adjacent characters in a string that are consecutive in the alphabet, considering the alphabet as circular. "Consecutive in the alphabet" means two characters where the difference in their positions in the alphabet is 1, either forwards or backwards, and 'a' and 'z' are also considered consecutive. The operation...

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LeetCode 3559 - Number of Ways to Assign Edge Weights II

LeetCode Problem 3559 Difficulty: 🔴 Hard Topics: Array, Math, Dynamic Programming, Bit Manipulation, Tree, Depth-First Search Solution Problem Understanding We are given an undirected tree with n nodes, rooted at node 1 . Every edge will eventually receive a weight of either 1 or 2 . For each query [u, v] , we only care about the unique path connecting u and v . All edges outside that path are...

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LeetCode 3549 - Multiply Two Polynomials

LeetCode Problem 3549 Difficulty: 🔴 Hard Topics: Array, Math Solution Problem Understanding The input arrays represent polynomials in coefficient form. If: poly1 = [a0, a1, a2, ...] then it represents: A(x) = a0 + a1x + a2x² + ... Similarly: poly2 = [b0, b1, b2, ...] represents: B(x) = b0 + b1x + b2x² + ... The task is to compute the product polynomial: R(x) = A(x) × B(x) and...

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LeetCode 3554 - Find Category Recommendation Pairs

LeetCode Problem 3554 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding This is a SQL database problem involving customer purchasing behavior across product categories. We are given two tables: ProductPurchases records which products each user purchased. A user may purchase multiple products, and each purchase has a quantity. The quantity is irrelevant for this problem because we only care whether a user bought from a category, not how much they...

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LeetCode 3553 - Minimum Weighted Subgraph With the Required Paths II

LeetCode Problem 3553 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Tree, Depth-First Search Solution Problem Understanding We are given a weighted, undirected tree with n nodes. Because the graph is a tree, there is exactly one simple path between any two nodes. For each query [src1, src2, dest] , we must find the minimum total weight of a connected subtree such that both src1 and src2 can reach...

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LeetCode 3552 - Grid Teleportation Traversal

LeetCode Problem 3552 Difficulty: 🟡 Medium Topics: Array, Hash Table, Breadth-First Search, Matrix Solution Problem Understanding This problem presents a 2D grid traversal scenario with obstacles and teleportation portals. You are given a matrix of characters representing cells. Empty cells '.' are freely passable, '#' represents obstacles that block movement, and uppercase letters 'A' - 'Z' are teleportation portals. The task is to move from the top-left (0, 0) to...

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LeetCode 3547 - Maximum Sum of Edge Values in a Graph

LeetCode Problem 3547 Difficulty: 🔴 Hard Topics: Math, Greedy, Graph Theory Solution Problem Understanding The graph is undirected, connected, and every node has degree at most 2. A connected graph where every node has degree at most 2 can only have one of two shapes: A simple path, containing exactly n - 1 edges. A simple cycle, containing exactly n edges. We must assign the numbers 1 through n to...

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LeetCode 3546 - Equal Sum Grid Partition I

LeetCode Problem 3546 Difficulty: 🟡 Medium Topics: Array, Matrix, Enumeration, Prefix Sum Solution LeetCode 3546 - Equal Sum Grid Partition I Problem Understanding This problem asks us to determine whether a rectangular grid of positive integers can be split into two parts with exactly the same sum using a single straight cut. The cut can be made in only one of two ways: A horizontal cut between two adjacent rows....

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LeetCode 3544 - Subtree Inversion Sum

LeetCode Problem 3544 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Tree, Depth-First Search Solution Problem Understanding This problem asks us to select a subset of nodes in a rooted tree such that each selected node triggers a subtree inversion, and inversions interact through ancestor-descendant relationships with a distance constraint. Each inversion multiplies all values in the corresponding subtree by −1, and multiple inversions stack multiplicatively, meaning each node’s final sign...

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LeetCode 3545 - Minimum Deletions for At Most K Distinct Characters

LeetCode Problem 3545 Difficulty: 🟢 Easy Topics: Hash Table, String, Greedy, Sorting, Counting Solution LeetCode 3545 - Minimum Deletions for At Most K Distinct Characters Problem Understanding The problem gives us a string s containing lowercase English letters and an integer k . We are allowed to delete any characters from the string, including multiple occurrences of the same character. After performing the deletions, the resulting string must contain at...

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LeetCode 3542 - Minimum Operations to Convert All Elements to Zero

LeetCode Problem 3542 Difficulty: 🟡 Medium Topics: Array, Hash Table, Stack, Greedy, Monotonic Stack Solution Problem Understanding The problem requires us to reduce all elements of a given non-negative integer array nums to zero using the fewest number of operations. Each operation allows selecting a contiguous subarray and setting all occurrences of the minimum non-negative integer in that subarray to zero. In essence, we can remove the "smallest" numbers in...

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LeetCode 3543 - Maximum Weighted K-Edge Path

LeetCode Problem 3543 Difficulty: 🟡 Medium Topics: Hash Table, Dynamic Programming, Graph Theory Solution LeetCode 3543 - Maximum Weighted K-Edge Path Problem Understanding We are given a directed acyclic graph (DAG) with n nodes and weighted directed edges. Each edge is represented as [u, v, w] , meaning there is a directed edge from node u to node v with weight w . The goal is to find a path...

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LeetCode 3540 - Minimum Time to Visit All Houses

LeetCode Problem 3540 Difficulty: 🟡 Medium Topics: Array, Prefix Sum Solution LeetCode 3540 - Minimum Time to Visit All Houses Problem Understanding This problem describes a set of n houses arranged in a circle. Between adjacent houses, there are two directed road systems: forward[i] is the distance from house i to (i + 1) % n . backward[i] is the distance from house i to (i - 1 + n)...

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LeetCode 3541 - Find Most Frequent Vowel and Consonant

LeetCode Problem 3541 Difficulty: 🟢 Easy Topics: Hash Table, String, Counting Solution Problem Understanding The problem requires analyzing a string s composed of lowercase English letters and determining the sum of the maximum frequency of vowels and the maximum frequency of consonants. Vowels are defined as 'a' , 'e' , 'i' , 'o' , and 'u' . All other letters are consonants. The frequency of a character is the number...

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LeetCode 3538 - Merge Operations for Minimum Travel Time

LeetCode Problem 3538 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Prefix Sum Solution Problem Understanding This problem presents a road of length l kilometers, segmented by n signs at strictly increasing positions, where the first sign is at the start of the road ( position[0] = 0 ) and the last sign is at the end of the road ( position[n-1] = l ). Each segment between consecutive signs has...

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LeetCode 3535 - Unit Conversion II

LeetCode Problem 3535 Difficulty: 🟡 Medium Topics: Array, Math, Depth-First Search, Breadth-First Search, Graph Theory Solution Problem Understanding The input describes a collection of unit conversion relationships. Each conversion is given as: source -> target with factor f meaning: 1 unit of source = f units of target The important observation is that there are exactly n - 1 conversion edges among n units, and the statement guarantees that unit...

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LeetCode 3536 - Maximum Product of Two Digits

LeetCode Problem 3536 Difficulty: 🟢 Easy Topics: Math, Sorting Solution LeetCode 3536 - Maximum Product of Two Digits Problem Understanding The problem gives us a positive integer n and asks us to find the maximum product that can be formed by multiplying any two digits that appear in the number. The input is a single integer. We must examine all of its digits and determine which pair of digits produces...

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LeetCode 3533 - Concatenated Divisibility

LeetCode Problem 3533 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution LeetCode 3533 - Concatenated Divisibility Problem Understanding We are given an array nums containing up to 13 positive integers and an integer k . We may reorder the numbers in any permutation. After choosing an ordering, we concatenate the decimal representations of the numbers to form a single large integer. The task is to find a...

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LeetCode 3529 - Count Cells in Overlapping Horizontal and Vertical Substrings

LeetCode Problem 3529 Difficulty: 🟡 Medium Topics: Array, String, Rolling Hash, String Matching, Matrix, Hash Function Solution Problem Understanding We are given a character matrix and a pattern string. The key observation is that the problem defines two unusual traversal orders: A horizontal traversal reads the matrix row by row, from left to right. When a row ends, reading continues at the beginning of the next row. A vertical traversal...

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LeetCode 3532 - Path Existence Queries in a Graph I

LeetCode Problem 3532 Difficulty: 🟡 Medium Topics: Array, Hash Table, Binary Search, Union-Find, Graph Theory Solution Path Existence Queries in a Graph I Problem Understanding This problem defines an undirected graph implicitly through a sorted array nums . Each index in nums represents a graph node. Two nodes i and j are connected by an edge whenever: $$|nums[i] - nums[j]| \le maxDiff$$ We are then given many connectivity queries. For...

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LeetCode 3530 - Maximum Profit from Valid Topological Order in DAG

LeetCode Problem 3530 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Graph Theory, Topological Sort, Bitmask Solution Problem Understanding The problem requires computing the maximum possible profit achievable by processing nodes of a Directed Acyclic Graph (DAG) in a valid topological order . Each node has a score, and the profit contribution of a node is its score multiplied by its position in the processing order (1-based). The goal...

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LeetCode 3527 - Find the Most Common Response

LeetCode Problem 3527 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Counting Solution LeetCode 3527 - Find the Most Common Response Problem Understanding This problem gives us a two dimensional array of strings called responses . Each responses[i] represents all survey responses collected on the i th day. A response is simply a string such as "good" , "ok" , or "bad" . The important detail is that duplicate responses...

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LeetCode 3525 - Find X Value of Array II

LeetCode Problem 3525 Difficulty: 🔴 Hard Topics: Array, Math, Segment Tree Solution Problem Understanding For each query, two things happen in order. First, we permanently update one element of nums : nums[index] = value This modification remains in effect for all future queries. Second, we conceptually remove the prefix nums[0..start-1] . After this removal, we are left with the suffix: nums[start..n-1] Now we must count how many ways we can...

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LeetCode 3524 - Find X Value of Array I

LeetCode Problem 3524 Difficulty: 🟡 Medium Topics: Array, Math, Dynamic Programming Solution LeetCode 3524 - Find X Value of Array I Problem Understanding The operation described in the problem may initially look unusual, but it is actually equivalent to choosing a non-empty contiguous subarray. When we remove a prefix and a suffix that do not overlap, the elements left behind form a contiguous segment of the original array. Conversely, every...

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LeetCode 3523 - Make Array Non-decreasing

LeetCode Problem 3523 Difficulty: 🟡 Medium Topics: Array, Stack, Greedy, Monotonic Stack Solution Problem Understanding The problem asks us to transform an integer array nums into a non-decreasing array by performing zero or more operations, where an operation consists of selecting a contiguous subarray and replacing it with its maximum value . The goal is to maximize the size of the resulting array after all operations. In other words, we...

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LeetCode 3518 - Smallest Palindromic Rearrangement II

LeetCode Problem 3518 Difficulty: 🔴 Hard Topics: Hash Table, Math, String, Combinatorics, Counting Solution Problem Understanding We are given a string s that is guaranteed to already be a palindrome. We may rearrange its characters, but the final rearranged string must also be a palindrome. Among all distinct palindromic permutations that can be formed from the characters of s , we must return the k -th lexicographically smallest one. If...

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LeetCode 3515 - Shortest Path in a Weighted Tree

LeetCode Problem 3515 Difficulty: 🔴 Hard Topics: Array, Tree, Depth-First Search, Binary Indexed Tree, Segment Tree Solution LeetCode 3515. Shortest Path in a Weighted Tree Problem Understanding We are given a weighted tree with n nodes, rooted at node 1 . A tree has exactly one simple path between any pair of nodes. Since the tree is rooted at node 1 , every node has a unique path from the...

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LeetCode 3514 - Number of Unique XOR Triplets II

LeetCode Problem 3514 Difficulty: 🟡 Medium Topics: Array, Math, Bit Manipulation, Enumeration Solution LeetCode 3514 - Number of Unique XOR Triplets II Problem Understanding We are given an integer array nums , and we must consider every triplet of indices (i, j, k) such that i <= j <= k . For each valid triplet, we compute: $$nums[i] \oplus nums[j] \oplus nums[k]$$ where ⊕ denotes the bitwise XOR operation. The...

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LeetCode 3511 - Make a Positive Array

LeetCode Problem 3511 Difficulty: 🟡 Medium Topics: Array, Greedy, Prefix Sum Solution Before diving into the detailed solution guide, I want to clarify one subtle point: the problem specifies that all subarrays with more than two elements must have a positive sum. This means the smallest subarray we need to consider is of length 3. This nuance is crucial for correctness. Here’s the comprehensive solution guide following your formatting rules....

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LeetCode 3513 - Number of Unique XOR Triplets I

LeetCode Problem 3513 Difficulty: 🟡 Medium Topics: Array, Math, Bit Manipulation Solution Problem Understanding The problem asks us to determine the number of unique values that can result from taking the XOR of three elements in a given array nums , where the triplets (i, j, k) must satisfy i <= j <= k . Importantly, nums is a permutation of integers from 1 to n , meaning every integer...

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LeetCode 3517 - Smallest Palindromic Rearrangement I

LeetCode Problem 3517 Difficulty: 🟡 Medium Topics: String, Sorting, Counting Sort Solution Problem Understanding The problem asks us to take a palindromic string s and return its lexicographically smallest palindromic permutation . In other words, we need to rearrange the characters of s into a palindrome that is the smallest possible if you were to compare it alphabetically with all other palindromic arrangements. The input string s is guaranteed to...

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LeetCode 3516 - Find Closest Person

LeetCode Problem 3516 Difficulty: 🟢 Easy Topics: Math Solution LeetCode 3516 - Find Closest Person Problem Understanding This problem gives us three integers, x , y , and z , representing the positions of three people on a one-dimensional number line. Person 1 starts at position x , Person 2 starts at position y , and Person 3 remains stationary at position z . Both Person 1 and Person 2...

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LeetCode 3512 - Minimum Operations to Make Array Sum Divisible by K

LeetCode Problem 3512 Difficulty: 🟢 Easy Topics: Array, Math Solution LeetCode 3512 - Minimum Operations to Make Array Sum Divisible by K Problem Understanding The problem gives us an integer array nums and an integer k . We are allowed to repeatedly perform one operation: choose any index i and decrease nums[i] by exactly 1 . Our goal is to determine the minimum number of such operations needed so that...

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LeetCode 3510 - Minimum Pair Removal to Sort Array II

LeetCode Problem 3510 Difficulty: 🔴 Hard Topics: Array, Hash Table, Linked List, Heap (Priority Queue), Simulation, Doubly-Linked List, Ordered Set Solution LeetCode 3510: Minimum Pair Removal to Sort Array II Problem Understanding We are given an array nums . The operation is highly constrained: Among all adjacent pairs, find the pair with the minimum sum. If multiple adjacent pairs have the same minimum sum, choose the leftmost one. Replace those...

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LeetCode 3509 - Maximum Product of Subsequences With an Alternating Sum Equal to K

LeetCode Problem 3509 Difficulty: 🔴 Hard Topics: Array, Hash Table, Dynamic Programming Solution Problem Understanding The problem asks us to find a subsequence of a given integer array nums such that the alternating sum of the subsequence equals a target integer k , while maximizing the product of the numbers in that subsequence without exceeding a given limit . The alternating sum is defined as the sum of elements at...

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LeetCode 3508 - Implement Router

LeetCode Problem 3508 Difficulty: 🟡 Medium Topics: Array, Hash Table, Binary Search, Design, Queue, Ordered Set Solution Problem Understanding The problem is asking us to design a Router data structure to manage network packets efficiently under memory constraints. Each packet has three attributes: source , destination , and timestamp . The router has a memory limit , meaning it can store only a fixed number of packets. If a new...

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LeetCode 3507 - Minimum Pair Removal to Sort Array I

LeetCode Problem 3507 Difficulty: 🟢 Easy Topics: Array, Hash Table, Linked List, Heap (Priority Queue), Simulation, Doubly-Linked List, Ordered Set Solution LeetCode 3507 - Minimum Pair Removal to Sort Array I Problem Understanding We are given an array nums . At any step, we are not free to choose any adjacent pair. Instead, the operation is completely determined by the current state of the array: Find the adjacent pair whose...

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LeetCode 3503 - Longest Palindrome After Substring Concatenation I

LeetCode Problem 3503 Difficulty: 🟡 Medium Topics: Two Pointers, String, Dynamic Programming, Enumeration Solution LeetCode 3503 - Longest Palindrome After Substring Concatenation I Problem Understanding We are given two strings, s and t , and we are allowed to choose: Any substring of s , including the empty string. Any substring of t , including the empty string. The chosen substring from s must come first, and the chosen substring...

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LeetCode 3497 - Analyze Subscription Conversion

LeetCode Problem 3497 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This is a SQL aggregation problem where we need to analyze user subscription behavior and return statistics only for users who successfully converted from a free trial to a paid subscription. The UserActivity table contains one row per user, per day, per activity type. The activity_type column can be one of three values: This is a SQL database problem...

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LeetCode 3493 - Properties Graph

LeetCode Problem 3493 Difficulty: 🟡 Medium Topics: Array, Hash Table, Depth-First Search, Breadth-First Search, Union-Find, Graph Theory Solution Problem Understanding The problem asks us to model a 2D array of integers, called properties , as an undirected graph. Each row of the array corresponds to a node in the graph. Two nodes are connected if the number of distinct integers they share is at least k . Our goal is...

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LeetCode 3499 - Maximize Active Section with Trade I

LeetCode Problem 3499 Difficulty: 🟡 Medium Topics: String, Enumeration Solution Problem Understanding The problem gives a binary string s representing sections of a system, where '1' indicates an active section and '0' indicates an inactive section. We are allowed at most one trade to maximize the number of active sections. A trade consists of two operations applied sequentially on the string: Convert a contiguous block of '1' s surrounded by...

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LeetCode 3501 - Maximize Active Section with Trade II

LeetCode Problem 3501 Difficulty: 🔴 Hard Topics: Array, String, Binary Search, Segment Tree Solution Problem Understanding The problem presents a binary string s where each character represents an active ( '1' ) or inactive ( '0' ) section. For each query, which specifies a substring of s , we are asked to determine the maximum number of active sections after performing at most one trade operation. A trade consists of...

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LeetCode 3500 - Minimum Cost to Divide Array Into Subarrays

LeetCode Problem 3500 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Prefix Sum Solution Problem Understanding This problem asks us to partition an array nums into contiguous subarrays, where each subarray contributes a weighted cost to the total. The cost for a subarray nums[l..r] depends on two components: the sum of the elements in the subarray, adjusted by a factor k multiplied by the order of the subarray, and the sum...

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LeetCode 3498 - Reverse Degree of a String

LeetCode Problem 3498 Difficulty: 🟢 Easy Topics: String, Simulation Solution LeetCode 3498 - Reverse Degree of a String Problem Understanding The problem asks us to compute a special value called the reverse degree of a string. Normally, letters are assigned positions in the alphabet as: 'a' = 1 'b' = 2 ... 'z' = 26 However, this problem uses the reversed alphabet order , where: 'a' = 26 'b' =...

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LeetCode 3492 - Maximum Containers on a Ship

LeetCode Problem 3492 Difficulty: 🟢 Easy Topics: Math Solution Problem Understanding This problem describes a cargo ship with an n × n deck. Since each cell on the deck can hold exactly one container, the deck has a total capacity of: $$n^2$$ physical container positions. Every container has the same weight, w . The ship also has a maximum total weight limit, maxWeight . Even if the deck has enough...

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LeetCode 3496 - Maximize Score After Pair Deletions

LeetCode Problem 3496 Difficulty: 🟡 Medium Topics: Array, Greedy Solution LeetCode 3496 - Maximize Score After Pair Deletions Problem Understanding We are given an integer array nums . While the array contains more than two elements, we must repeatedly perform one of three operations: Remove the first two elements. Remove the last two elements. Remove the first and last element. Whenever we remove a pair, we add the sum of...

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LeetCode 3494 - Find the Minimum Amount of Time to Brew Potions

LeetCode Problem 3494 Difficulty: 🟡 Medium Topics: Array, Simulation, Prefix Sum Solution Problem Understanding The problem asks us to simulate a sequential brewing process for potions performed by a series of wizards. Each wizard has a skill level that determines the speed at which they brew a potion, while each potion has a mana requirement that affects how long it takes to brew. Specifically, the time for wizard i to...

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LeetCode 3491 - Phone Number Prefix

LeetCode Problem 3491 Difficulty: 🟢 Easy Topics: Array, String, Trie, Sorting Solution Problem Understanding The problem is asking us to determine whether any phone number in a given list is a prefix of another phone number. In simpler terms, if you have a list of strings representing numbers, you need to check that no string starts with another string from the list. If all numbers are independent prefixes, the output...

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LeetCode 3490 - Count Beautiful Numbers

LeetCode Problem 3490 Difficulty: 🔴 Hard Topics: Dynamic Programming Solution Problem Understanding This problem asks us to count the number of positive integers between l and r (inclusive) that are beautiful . A number is defined as beautiful if the product of its digits is divisible by the sum of its digits. In simpler terms, for a number n , if sum_digits(n) divides product_digits(n) evenly, then n is beautiful. The...

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LeetCode 3489 - Zero Array Transformation IV

LeetCode Problem 3489 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding The problem asks us to determine the minimum number of sequential queries needed to transform an integer array nums into a Zero Array, where every element is zero. Each query specifies a subarray [li, ri] and a value vali , and the query allows us to decrement any subset of indices in that subarray by exactly vali...

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LeetCode 3488 - Closest Equal Element Queries

LeetCode Problem 3488 Difficulty: 🟡 Medium Topics: Array, Hash Table, Binary Search Solution Problem Understanding The problem asks us to process a series of queries on a circular array nums . Each query specifies an index, and for that index, we need to find the minimum circular distance to any other index with the same value. The circular distance means that after the last element, the array wraps back to...

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LeetCode 3486 - Longest Special Path II

LeetCode Problem 3486 Difficulty: 🔴 Hard Topics: Array, Hash Table, Tree, Depth-First Search, Prefix Sum Solution LeetCode 3486 - Longest Special Path II Problem Understanding We are given a rooted tree with n nodes. The tree is rooted at node 0 , and every edge has a positive length. Each node also contains a value stored in the array nums . A path is considered special if it satisfies two...

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LeetCode 3480 - Maximize Subarrays After Removing One Conflicting Pair

LeetCode Problem 3480 Difficulty: 🔴 Hard Topics: Array, Segment Tree, Enumeration, Prefix Sum Solution Here’s a detailed technical solution guide following your requested format for LeetCode 3480 - Maximize Subarrays After Removing One Conflicting Pair . Problem Understanding The problem gives you an integer n , which defines a sorted array nums = [1, 2, ..., n] . You are also given a list of conflictingPairs , each representing two...

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LeetCode 3484 - Design Spreadsheet

LeetCode Problem 3484 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Design, Matrix Solution LeetCode 3484 - Design Spreadsheet Problem Understanding This problem asks us to design a very small spreadsheet system that supports three operations on cells and one operation for evaluating simple formulas. The spreadsheet always contains exactly 26 columns, labeled 'A' through 'Z' , and a configurable number of rows. Each cell can store an integer value....

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LeetCode 3476 - Maximize Profit from Task Assignment

LeetCode Problem 3476 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting, Heap (Priority Queue) Solution Problem Understanding This problem asks us to assign tasks to workers in order to maximize total profit, under strict skill constraints. Each worker has a skill level, and each task has a required skill and an associated profit. A worker can only complete a task if their skill exactly matches the task's required skill. Additionally, there...

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LeetCode 3481 - Apply Substitutions

LeetCode Problem 3481 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Depth-First Search, Breadth-First Search, Graph Theory, Topological Sort Solution LeetCode 3481 - Apply Substitutions Problem Understanding This problem gives us a collection of replacement rules and a text containing placeholders. Every placeholder has the format %X% , where X is a single uppercase letter corresponding to one of the replacement keys. The important detail is that replacement values may...

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LeetCode 3474 - Lexicographically Smallest Generated String

LeetCode Problem 3474 Difficulty: 🔴 Hard Topics: String, Greedy, String Matching Solution LeetCode 3474 - Lexicographically Smallest Generated String Problem Understanding We are given two strings: str1 of length n , containing only 'T' and 'F' str2 of length m , containing lowercase English letters We must construct a string word of length n + m - 1 . For every position i in str1 , the substring of word...

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LeetCode 3479 - Fruits Into Baskets III

LeetCode Problem 3479 Difficulty: 🟡 Medium Topics: Array, Binary Search, Segment Tree, Ordered Set Solution LeetCode 3479: Fruits Into Baskets III Problem Understanding This problem gives us two arrays of equal length: fruits[i] represents the quantity of the i-th fruit type. baskets[j] represents the capacity of the j-th basket. We process the fruit types from left to right. For each fruit quantity, we must place it into the leftmost available...

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LeetCode 3478 - Choose K Elements With Maximum Sum

LeetCode Problem 3478 Difficulty: 🟡 Medium Topics: Array, Sorting, Heap (Priority Queue) Solution Problem Understanding This problem asks us to compute a "maximum sum" for each index in an array based on a relationship with other elements. Specifically, for each index i in nums1 , we must consider all previous or other indices j where nums1[j] < nums1[i] , and then select up to k values from nums2[j] to maximize...

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LeetCode 3477 - Fruits Into Baskets II

LeetCode Problem 3477 Difficulty: 🟢 Easy Topics: Array, Binary Search, Segment Tree, Simulation, Ordered Set Solution Problem Understanding This problem asks us to simulate the placement of fruits into baskets following very specific rules. We are given two arrays of equal length, fruits and baskets . Each element in fruits represents the quantity of a fruit type, and each element in baskets represents the capacity of a basket. We need...

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LeetCode 3475 - DNA Pattern Recognition

LeetCode Problem 3475 Difficulty: 🟡 Medium Topics: Database Solution LeetCode 3475 - DNA Pattern Recognition Problem Understanding This problem provides a database table named Samples that contains DNA sequences and their associated species. Each row represents a single biological sample, identified by a unique sample_id . The task is to examine every DNA sequence and determine whether it matches four different biological patterns. For each sample, we must generate four...

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LeetCode 3471 - Find the Largest Almost Missing Integer

LeetCode Problem 3471 Difficulty: 🟢 Easy Topics: Array, Hash Table Solution LeetCode 3471 - Find the Largest Almost Missing Integer Problem Understanding The problem gives us an integer array nums and an integer k . We consider every contiguous subarray of length k . An integer is called almost missing if it appears in exactly one of those size- k subarrays. Our goal is to find the largest integer that...

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LeetCode 3461 - Check If Digits Are Equal in String After Operations I

LeetCode Problem 3461 Difficulty: 🟢 Easy Topics: Math, String, Simulation, Combinatorics, Number Theory Solution Problem Understanding This problem asks us to repeatedly transform a string of digits by summing consecutive pairs modulo 10, until only two digits remain, and then check whether those two digits are equal. In other words, we start with a string s of length at least 3 and, at each step, generate a new string where...

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LeetCode 3472 - Longest Palindromic Subsequence After at Most K Operations

LeetCode Problem 3472 Difficulty: 🟡 Medium Topics: String, Dynamic Programming Solution Here’s a complete, detailed technical solution guide for LeetCode 3472 following your formatting rules. Problem Understanding The problem asks us to find the length of the longest palindromic subsequence in a string s after performing at most k operations . Each operation allows us to increment or decrement a character by one in the alphabet, with wraparound from 'a'...

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LeetCode 3470 - Permutations IV

LeetCode Problem 3470 Difficulty: 🔴 Hard Topics: Array, Math, Combinatorics, Enumeration Solution LeetCode 3470 - Permutations IV Problem Understanding We are given two integers, n and k . We must consider all permutations of the numbers 1 through n that satisfy an alternating parity condition. In a valid permutation, every pair of adjacent elements must have different parity. In other words: Odd must be followed by even. Even must be...

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LeetCode 3469 - Find Minimum Cost to Remove Array Elements

LeetCode Problem 3469 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding The problem is asking for the minimum total cost required to remove all elements from an integer array nums under a very specific set of operations. At each step, we can either remove any two elements from the first three elements of the array, and the cost for that operation is the maximum of the two elements...

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LeetCode 3467 - Transform Array by Parity

LeetCode Problem 3467 Difficulty: 🟢 Easy Topics: Array, Sorting, Counting Solution LeetCode 3467 - Transform Array by Parity Problem Understanding The problem gives us an integer array nums and asks us to transform it using three operations that must be performed in a specific order. First, every even number must be replaced with 0 . Second, every odd number must be replaced with 1 . After this transformation, the array...

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LeetCode 3459 - Length of Longest V-Shaped Diagonal Segment

LeetCode Problem 3459 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Memoization, Matrix Solution Problem Understanding We are given an n x m matrix whose entries are only 0 , 1 , or 2 . A valid V-shaped diagonal segment must satisfy two independent requirements: First, the values along the path must follow a very specific sequence. The first cell must contain 1 . Every subsequent cell must alternate between 2...

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LeetCode 3465 - Find Products with Valid Serial Numbers

LeetCode Problem 3465 Difficulty: 🟢 Easy Topics: Database Solution Problem Understanding The problem asks us to query a database table called products to identify rows where the description column contains a valid serial number. A valid serial number is defined as a substring that begins with "SN", followed by exactly four digits, a hyphen, and then exactly four more digits. For example, SN1234-5678 is valid, but SN123-4567 or SN12345-6789 are...

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LeetCode 3462 - Maximum Sum With at Most K Elements

LeetCode Problem 3462 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting, Heap (Priority Queue), Matrix Solution Problem Understanding We are given a matrix grid , where each row contains a collection of values that can potentially be selected. We are also given an array limits , where limits[i] specifies the maximum number of elements that may be chosen from row i . The goal is to select at most k elements...

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LeetCode 3463 - Check If Digits Are Equal in String After Operations II

LeetCode Problem 3463 Difficulty: 🔴 Hard Topics: Math, String, Combinatorics, Number Theory Solution Problem Understanding The problem asks us to repeatedly transform a string of digits until only two digits remain, and then check if those two digits are the same. The transformation involves taking each consecutive pair of digits, summing them, and taking the result modulo 10 to form a new digit. This process is applied repeatedly, replacing the...

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LeetCode 3460 - Longest Common Prefix After at Most One Removal

LeetCode Problem 3460 Difficulty: 🟡 Medium Topics: Two Pointers, String Solution LeetCode 3460 - Longest Common Prefix After at Most One Removal Problem Understanding We are given two lowercase strings, s and t . We may remove at most one character from s . The removal is optional, so we are also allowed to leave s unchanged. After performing zero or one removal, we want to compute the length of...

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LeetCode 3449 - Maximize the Minimum Game Score

LeetCode Problem 3449 Difficulty: 🔴 Hard Topics: Array, Binary Search, Greedy Solution Problem Understanding You are given an array points , where points[i] is the amount added to gameScore[i] every time you land on index i . The player starts outside the array at position -1 . Each move changes the current position by exactly one: Moving right from i to i + 1 Moving left from i to i...

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LeetCode 3458 - Select K Disjoint Special Substrings

LeetCode Problem 3458 Difficulty: 🟡 Medium Topics: Hash Table, String, Dynamic Programming, Greedy, Sorting Solution Problem Understanding The problem asks us to determine whether we can select k disjoint special substrings from a given string s . A special substring is defined as a substring where every character in it does not appear anywhere else in the string. Additionally, the substring cannot be the entire string itself. The input consists...

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LeetCode 3457 - Eat Pizzas!

LeetCode Problem 3457 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting Solution Problem Understanding The problem presents an array pizzas of size n where each element represents the weight of a pizza. Every day, you must eat exactly 4 pizzas , and the total weight you gain from these 4 pizzas depends on whether the day is odd or even. On odd-numbered days, your weight gain is equal to the heaviest...

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LeetCode 3456 - Find Special Substring of Length K

LeetCode Problem 3456 Difficulty: 🟢 Easy Topics: String Solution LeetCode 3456 - Find Special Substring of Length K Problem Understanding The problem gives us a string s and an integer k . We need to determine whether there exists a substring of length exactly k that satisfies three conditions. First, every character inside the substring must be identical. In other words, the substring must consist of only one distinct character...

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LeetCode 3454 - Separate Squares II

LeetCode Problem 3454 Difficulty: 🔴 Hard Topics: Array, Binary Search, Segment Tree, Sweep Line Solution LeetCode 3454 - Separate Squares II Problem Understanding This problem asks us to find the smallest horizontal line y = H that divides the union area of a collection of axis-aligned squares into two equal halves. Each square is represented as: (xi, yi) = bottom-left corner li = side length Therefore, a square covers: x-range:...

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LeetCode 3450 - Maximum Students on a Single Bench

LeetCode Problem 3450 Difficulty: 🟢 Easy Topics: Array, Hash Table Solution Problem Understanding The problem provides a list of student-seat assignments, where each entry has the form [student_id, bench_id] . Each pair indicates that a particular student is sitting on a particular bench. The goal is to determine which bench has the largest number of unique students sitting on it and return that count. The important detail is that a...

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LeetCode 3452 - Sum of Good Numbers

LeetCode Problem 3452 Difficulty: 🟢 Easy Topics: Array Solution LeetCode 3452 - Sum of Good Numbers Problem Understanding This problem gives us an integer array nums and an integer k . For every position i , we need to determine whether nums[i] is a good number. A number is considered good if it is strictly greater than the element located k positions to its left, nums[i - k] , when...

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LeetCode 3451 - Find Invalid IP Addresses

LeetCode Problem 3451 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding This is a SQL database problem where we must identify all invalid IPv4 addresses that appear in the logs table and count how many times each invalid address occurs. The input table contains one row per server access log. Each row includes a unique log_id , an IP address stored as a string in the ip column, and an...

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LeetCode 3448 - Count Substrings Divisible By Last Digit

LeetCode Problem 3448 Difficulty: 🔴 Hard Topics: String, Dynamic Programming Solution LeetCode 3448 - Count Substrings Divisible By Last Digit Problem Understanding We are given a string s consisting only of decimal digits. Every substring of s represents a non-negative integer, and leading zeros are allowed. For each substring, we look at its last digit. If the last digit is non-zero, we check whether the numeric value of the substring...

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LeetCode 3446 - Sort Matrix by Diagonals

LeetCode Problem 3446 Difficulty: 🟡 Medium Topics: Array, Sorting, Matrix Solution Problem Understanding We are given an n x n square matrix grid . Every cell belongs to exactly one top-left to bottom-right diagonal. Two cells (r1, c1) and (r2, c2) are on the same diagonal if r1 - c1 == r2 - c2 . The problem asks us to independently sort each diagonal, but the required sorting order depends...

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LeetCode 3442 - Maximum Difference Between Even and Odd Frequency I

LeetCode Problem 3442 Difficulty: 🟢 Easy Topics: Hash Table, String, Counting Solution Problem Understanding This problem requires analyzing the frequency of characters in a given string and computing a specific difference. You are given a string s consisting only of lowercase English letters. For each character in the string, you can count how many times it appears. Some characters will appear an odd number of times , and some will...

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LeetCode 3447 - Assign Elements to Groups with Constraints

LeetCode Problem 3447 Difficulty: 🟡 Medium Topics: Array, Hash Table Solution Problem Understanding The problem requires assigning elements from one array, elements , to groups defined by another array, groups , under a divisibility constraint. Specifically, for each group groups[i] , we must find the smallest index j in elements such that groups[i] % elements[j] == 0 . If no such element exists, we assign -1 for that group. Multiple...

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LeetCode 3444 - Minimum Increments for Target Multiples in an Array

LeetCode Problem 3444 Difficulty: 🔴 Hard Topics: Array, Math, Dynamic Programming, Bit Manipulation, Number Theory, Bitmask Solution LeetCode 3444 - Minimum Increments for Target Multiples in an Array Problem Understanding We are given two arrays: nums , the array whose elements we are allowed to increase. target , a small array containing values that must each be represented by at least one multiple somewhere in the final version of nums...

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LeetCode 3441 - Minimum Cost Good Caption

LeetCode Problem 3441 Difficulty: 🔴 Hard Topics: String, Dynamic Programming Solution Problem Understanding We are given a lowercase string caption . We may repeatedly change any character one step forward or backward in the alphabet. Because we can apply this operation multiple times, converting a character x into a character y costs exactly: $$|x - y|$$ where the difference is measured by alphabet position. The goal is to transform the...

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LeetCode 3440 - Reschedule Meetings for Maximum Free Time II

LeetCode Problem 3440 Difficulty: 🟡 Medium Topics: Array, Greedy, Enumeration Solution LeetCode 3440 - Reschedule Meetings for Maximum Free Time II Problem Understanding We are given an event that lasts from time 0 to eventTime . Inside this event there are n non-overlapping meetings, represented by the arrays startTime and endTime . The meeting at index i occupies the interval: [startTime[i], endTime[i]] The meetings are already sorted and non-overlapping, meaning:...

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LeetCode 3439 - Reschedule Meetings for Maximum Free Time I

LeetCode Problem 3439 Difficulty: 🟡 Medium Topics: Array, Greedy, Sliding Window Solution Problem Understanding We are given an event that runs from time 0 to eventTime . Inside this event there are n non-overlapping meetings, already arranged in chronological order. Each meeting i occupies the interval: [startTime[i], endTime[i]] The meetings do not overlap, and the input guarantees: endTime[i] <= startTime[i + 1] which means there may be free time between...

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LeetCode 3437 - Permutations III

LeetCode Problem 3437 Difficulty: 🟡 Medium Topics: Array, Backtracking Solution LeetCode 3437 - Permutations III Problem Understanding We are given a single integer n , and we need to generate all permutations of the numbers from 1 to n . However, not every permutation is valid. A permutation is considered an alternating permutation if every pair of adjacent elements has different parity. In other words: An odd number must always...

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LeetCode 3436 - Find Valid Emails

LeetCode Problem 3436 Difficulty: 🟢 Easy Topics: Database Solution Problem Understanding The problem requires us to identify valid email addresses from a Users table in a database. Each row contains a user_id and an email string. The definition of a valid email is very specific: it must contain exactly one @ symbol , end with .com , have a local part (before the @ ) composed solely of alphanumeric characters...

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LeetCode 3435 - Frequencies of Shortest Supersequences

LeetCode Problem 3435 Difficulty: 🔴 Hard Topics: Array, String, Bit Manipulation, Graph Theory, Topological Sort, Enumeration Solution Problem Understanding The problem asks us to find all shortest common supersequences (SCS) of a given list of two-character strings words . A shortest common supersequence is a string of minimum length that contains each word in words as a subsequence. Importantly, the output should not include SCSs that are permutations of each...

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LeetCode 3433 - Count Mentions Per User

LeetCode Problem 3433 Difficulty: 🟡 Medium Topics: Array, Math, Sorting, Simulation Solution LeetCode 3433 - Count Mentions Per User Problem Understanding This problem asks us to simulate a sequence of user activity events and count how many times each user is mentioned across all message events. We are given: numberOfUsers , the total number of users with IDs from 0 to numberOfUsers - 1 events , where each event is...

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LeetCode 3428 - Maximum and Minimum Sums of at Most Size K Subsequences

LeetCode Problem 3428 Difficulty: 🟡 Medium Topics: Array, Math, Dynamic Programming, Sorting, Combinatorics Solution Problem Understanding We are given an array nums and an integer k . For every subsequence whose size is at most k , we look at two values: The minimum element in that subsequence. The maximum element in that subsequence. We add minimum + maximum for every valid subsequence, then return the total modulo 10^9 +...

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LeetCode 3429 - Paint House IV

LeetCode Problem 3429 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding This problem is asking us to paint n houses arranged in a line with three available colors for each house, minimizing the total painting cost while satisfying two constraints. The first constraint is the standard one from the classic "Paint House" problem: no two adjacent houses can have the same color. The second constraint is new and...

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LeetCode 3427 - Sum of Variable Length Subarrays

LeetCode Problem 3427 Difficulty: 🟢 Easy Topics: Array, Prefix Sum Solution Problem Understanding The problem provides an integer array nums of length n . For each index i , we are asked to consider a subarray that ends at i but starts at start = max(0, i - nums[i]) . This effectively means the subarray has a variable length depending on the value of nums[i] but never extends beyond the...

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LeetCode 3425 - Longest Special Path

LeetCode Problem 3425 Difficulty: 🔴 Hard Topics: Array, Hash Table, Tree, Depth-First Search, Prefix Sum Solution Problem Understanding This problem provides an undirected tree rooted at node 0 with n nodes and weighted edges, where each node has a value defined in the array nums . A special path is a downward path (from ancestor to descendant) such that all node values along the path are unique . The path...

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LeetCode 3424 - Minimum Cost to Make Arrays Identical

LeetCode Problem 3424 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting Solution Problem Understanding The problem asks us to transform one integer array arr into another integer array brr with the minimum cost using two types of operations. The first operation allows splitting arr into contiguous subarrays and rearranging them at a fixed cost k per operation. The second operation allows adjusting any element by adding or subtracting a positive integer...

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LeetCode 3423 - Maximum Difference Between Adjacent Elements in a Circular Array

LeetCode Problem 3423 Difficulty: 🟢 Easy Topics: Array Solution LeetCode 3423 - Maximum Difference Between Adjacent Elements in a Circular Array Problem Understanding This problem gives us an integer array nums and asks us to find the largest absolute difference between any two adjacent elements. The important detail is that the array is circular . In a normal array, element i is adjacent only to elements i - 1 and...

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LeetCode 3422 - Minimum Operations to Make Subarray Elements Equal

LeetCode Problem 3422 Difficulty: 🟡 Medium Topics: Array, Hash Table, Math, Sliding Window, Heap (Priority Queue) Solution LeetCode 3422 - Minimum Operations to Make Subarray Elements Equal Problem Understanding We are given an array nums and an integer k . In a single operation, we may increase or decrease any element by exactly 1 . Our goal is not to make the entire array equal. Instead, we only need at...

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LeetCode 3420 - Count Non-Decreasing Subarrays After K Operations

LeetCode Problem 3420 Difficulty: 🔴 Hard Topics: Array, Stack, Segment Tree, Queue, Sliding Window, Monotonic Stack, Monotonic Queue Solution Problem Understanding You are given an array nums and a budget of at most k increment operations. For any chosen subarray, you may repeatedly pick an element inside that subarray and increase it by 1 . The goal is to determine whether that subarray can be transformed into a non-decreasing array...

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LeetCode 3418 - Maximum Amount of Money Robot Can Earn

LeetCode Problem 3418 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Matrix Solution Problem Understanding We are given an m x n grid where each cell contains either a positive value, zero, or a negative value. The robot starts at the top-left cell (0, 0) and must reach the bottom-right cell (m - 1, n - 1) . At every step it may only move either right or down, so every...

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LeetCode 3417 - Zigzag Grid Traversal With Skip

LeetCode Problem 3417 Difficulty: 🟢 Easy Topics: Array, Matrix, Simulation Solution LeetCode 3417 - Zigzag Grid Traversal With Skip Problem Understanding This problem asks us to traverse a two-dimensional grid in a zigzag order while visiting only every other cell in the traversal sequence. The zigzag traversal follows a very specific pattern: Start at the top-left corner (0, 0) . Traverse the first row from left to right. Move down...

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LeetCode 3416 - Subsequences with a Unique Middle Mode II

LeetCode Problem 3416 Difficulty: 🔴 Hard Topics: Array, Hash Table, Math, Combinatorics Solution Problem Understanding We are given an array nums , and we must count how many subsequences of length exactly 5 have a very specific property. For any chosen subsequence $$[a,b,c,d,e]$$ the middle element is c , because it is the third element of a length-5 sequence. The subsequence is valid if: c is a mode of the...

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LeetCode 3413 - Maximum Coins From K Consecutive Bags

LeetCode Problem 3413 Difficulty: 🟡 Medium Topics: Array, Binary Search, Greedy, Sliding Window, Sorting, Prefix Sum Solution LeetCode 3413 - Maximum Coins From K Consecutive Bags Problem Understanding We are given several non-overlapping segments on a number line. Each segment [l, r, c] means that every bag at positions l, l+1, ..., r contains exactly c coins. All positions not covered by any segment contain 0 coins. The goal is...

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LeetCode 3411 - Maximum Subarray With Equal Products

LeetCode Problem 3411 Difficulty: 🟢 Easy Topics: Array, Math, Sliding Window, Enumeration, Number Theory Solution LeetCode 3411 - Maximum Subarray With Equal Products Problem Understanding We are given an array nums consisting of positive integers. For any array arr , define: prod(arr) as the product of all elements. gcd(arr) as the greatest common divisor of all elements. lcm(arr) as the least common multiple of all elements. A subarray is called...

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LeetCode 3409 - Longest Subsequence With Decreasing Adjacent Difference

LeetCode Problem 3409 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution LeetCode 3409 - Longest Subsequence With Decreasing Adjacent Difference Problem Understanding We are given an array nums , and we want to choose a subsequence from it. A subsequence preserves the original order of elements but may skip arbitrary positions. For a chosen subsequence $$seq_0, seq_1, seq_2, \dots, seq_m$$ we look at the absolute differences between consecutive elements: $$|seq_1-seq_0|,...

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LeetCode 3408 - Design Task Manager

LeetCode Problem 3408 Difficulty: 🟡 Medium Topics: Hash Table, Design, Heap (Priority Queue), Ordered Set Solution LeetCode 3408. Design Task Manager Problem Understanding This problem asks us to design a data structure that maintains a collection of tasks belonging to different users. Each task has three pieces of information: userId , the user who owns the task taskId , a unique identifier for the task priority , which determines execution...

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LeetCode 3407 - Substring Matching Pattern

LeetCode Problem 3407 Difficulty: 🟢 Easy Topics: String, String Matching Solution LeetCode 3407. Substring Matching Pattern Problem Understanding The problem gives us two strings: s , the source string. p , a pattern string containing exactly one '*' . The special character '*' can represent any sequence of characters, including an empty sequence. The goal is to determine whether there exists some substring of s that can match the pattern...

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LeetCode 3403 - Find the Lexicographically Largest String From the Box I

LeetCode Problem 3403 Difficulty: 🟡 Medium Topics: Two Pointers, String, Enumeration Solution LeetCode 3403 - Find the Lexicographically Largest String From the Box I Problem Understanding We are given a string word of length n and an integer numFriends . In each round, the string is split into exactly numFriends non-empty contiguous pieces. Every distinct way to place the numFriends - 1 cuts is considered a different round. After each...

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LeetCode 3376 - Minimum Time to Break Locks I

LeetCode Problem 3376 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Breadth-First Search, Bitmask Solution LeetCode 3376 - Minimum Time to Break Locks I Problem Understanding The problem describes a sequence of locks that must all be broken. Each lock requires a certain amount of energy, given by strength[i] . Bob's sword starts with: Energy = 0 Growth factor x = 1 Every minute, the sword gains x...

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LeetCode 3183 - The Number of Ways to Make the Sum

LeetCode Problem 3183 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding The problem asks us to determine the number of distinct ways to sum up to an integer n using a limited set of coins. Specifically, we have coins of value 1, 2, and 6 available in infinite quantities, and coins of value 4 with a strict limit of two. The key points are that the order of...

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LeetCode 1847 - Closest Room

LeetCode Problem 1847 Difficulty: 🔴 Hard Topics: Array, Binary Search, Sorting, Ordered Set Solution LeetCode 1847: Closest Room Problem Understanding We are given a list of hotel rooms, where each room has: Problem Understanding The problem gives us a collection of hotel rooms, where each room has two attributes: A unique room ID A room size We are also given several queries. Each query contains: preferred : the room ID...

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LeetCode 3399 - Smallest Substring With Identical Characters II

LeetCode Problem 3399 Difficulty: 🔴 Hard Topics: String, Binary Search Solution Problem Understanding We are given a binary string s consisting only of '0' and '1' , along with an integer numOps . In one operation, we may choose any index and flip the bit at that position. A '0' becomes '1' , and a '1' becomes '0' . Our goal is not to minimize the total number of changes...

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LeetCode 3390 - Longest Team Pass Streak

LeetCode Problem 3390 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding This problem asks us to analyze a football match pass sequence and determine, for every team, the longest uninterrupted sequence of successful passes between players on the same team. We are given two tables: The Teams table maps each player_id to a team_name . Every player belongs to exactly one team. The Passes table records passes made during the...

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LeetCode 3375 - Minimum Operations to Make Array Values Equal to K

LeetCode Problem 3375 Difficulty: 🟢 Easy Topics: Array, Hash Table Solution LeetCode 3375 - Minimum Operations to Make Array Values Equal to K Problem Understanding The problem gives us an integer array nums and a target value k . Our goal is to transform the entire array so that every element becomes exactly equal to k . However, we cannot arbitrarily change values. Each operation follows a very specific rule....

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LeetCode 3372 - Maximize the Number of Target Nodes After Connecting Trees I

LeetCode Problem 3372 Difficulty: 🟡 Medium Topics: Tree, Depth-First Search, Breadth-First Search Solution LeetCode 3372 - Maximize the Number of Target Nodes After Connecting Trees I Problem Understanding We are given two separate undirected trees. The first tree contains n nodes labeled from 0 to n - 1 , and the second tree contains m nodes labeled from 0 to m - 1 . A node u is considered a...

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LeetCode 3360 - Stone Removal Game

LeetCode Problem 3360 Difficulty: 🟢 Easy Topics: Math, Simulation Solution Problem Understanding In this game, Alice and Bob take turns removing stones from a pile. The rules are very strict because the number of stones removed on each turn is predetermined. Alice always goes first and must remove exactly 10 stones on her first move. After that, each move removes exactly 1 fewer stone than the previous move. This means...

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LeetCode 3335 - Total Characters in String After Transformations I

LeetCode Problem 3335 Difficulty: 🟡 Medium Topics: Hash Table, Math, String, Dynamic Programming, Counting Solution Problem Understanding The problem gives us a string s and an integer t . We repeatedly apply a transformation exactly t times. During one transformation: Every character from 'a' to 'y' becomes the next character in the alphabet. The character 'z' becomes the string "ab" . After all transformations are complete, we must return the...

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LeetCode 3333 - Find the Original Typed String II

LeetCode Problem 3333 Difficulty: 🔴 Hard Topics: String, Dynamic Programming, Prefix Sum Solution Problem Understanding The problem asks us to determine the number of possible original strings that Alice could have intended to type, given a string word that represents the final output and an integer k representing the minimum length of the original string. Because Alice may press keys too long, each character in the output may correspond to...

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LeetCode 3270 - Find the Key of the Numbers

LeetCode Problem 3270 Difficulty: 🟢 Easy Topics: Math Solution Problem Understanding The problem gives us three positive integers, num1 , num2 , and num3 . We must construct a new number called the key using the digits of these three numbers. The important detail is that every number must first be treated as a four digit number. If a number has fewer than four digits, we pad it with leading...

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LeetCode 3260 - Find the Largest Palindrome Divisible by K

LeetCode Problem 3260 Difficulty: 🔴 Hard Topics: Math, String, Dynamic Programming, Greedy, Number Theory Solution LeetCode 3260 - Find the Largest Palindrome Divisible by K Problem Understanding The problem asks us to construct the largest possible palindrome with exactly n digits such that the resulting number is divisible by k . A palindrome is a number that reads the same forward and backward. For example, 595 , 1221 , and...

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LeetCode 3224 - Minimum Array Changes to Make Differences Equal

LeetCode Problem 3224 Difficulty: 🟡 Medium Topics: Array, Hash Table, Prefix Sum Solution Problem Understanding The problem gives us an integer array nums of even length n and an integer k . We are allowed to change any element in nums to any integer in the range [0, k] . Our goal is to ensure that for all symmetric pairs (nums[i], nums[n - i - 1]) , the absolute difference...

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LeetCode 3206 - Alternating Groups I

LeetCode Problem 3206 Difficulty: 🟢 Easy Topics: Array, Sliding Window Solution Problem Understanding The problem gives us a circular array called colors , where each element represents the color of a tile: 0 means red 1 means blue Because the tiles form a circle, the first and last tiles are considered adjacent. We need to count how many groups of exactly 3 contiguous tiles form an alternating group. A group...

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LeetCode 3188 - Find Top Scoring Students II

LeetCode Problem 3188 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding This problem asks us to identify students who satisfy a combination of academic requirements based on their major, completed courses, grades, and overall GPA. We are given three tables: The students table stores each student's identity and declared major. The courses table stores information about courses, including which major they belong to and whether they are mandatory or elective....

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LeetCode 3176 - Find the Maximum Length of a Good Subsequence I

LeetCode Problem 3176 Difficulty: 🟡 Medium Topics: Array, Hash Table, Dynamic Programming Solution Problem Understanding We are given an integer array nums and a non-negative integer k . We need to find the maximum possible length of a subsequence such that the number of adjacent unequal pairs is at most k . A subsequence is formed by deleting zero or more elements from the array without changing the order of...

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LeetCode 3151 - Special Array I

LeetCode Problem 3151 Difficulty: 🟢 Easy Topics: Array Solution Problem Understanding The problem asks us to determine whether a given integer array is "special". An array is considered special if every pair of adjacent elements has different parity. Parity refers to whether a number is even or odd. Two numbers have different parity if one is even and the other is odd. For example: 2 and 5 have different parity...

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LeetCode 3119 - Maximum Number of Potholes That Can Be Fixed

LeetCode Problem 3119 Difficulty: 🟡 Medium Topics: String, Greedy, Sorting Solution LeetCode 3119 - Maximum Number of Potholes That Can Be Fixed Problem Understanding We are given a road represented as a string containing only two characters: 'x' represents a pothole. '.' represents a smooth section of road. We are also given a repair budget. A repair operation can only be applied to a contiguous group of potholes. If we...

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LeetCode 3135 - Equalize Strings by Adding or Removing Characters at Ends

LeetCode Problem 3135 Difficulty: 🟡 Medium Topics: String, Binary Search, Dynamic Programming, Sliding Window, Hash Function Solution Problem Understanding The problem gives us two strings, initial and target . We want to transform initial into target using the minimum number of operations. In a single operation, we may either: Add one character to the beginning of the string Add one character to the end of the string Remove one character...

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LeetCode 3108 - Minimum Cost Walk in Weighted Graph

LeetCode Problem 3108 Difficulty: 🔴 Hard Topics: Array, Bit Manipulation, Union-Find, Graph Theory Solution Problem Understanding This problem gives us an undirected weighted graph with n vertices and up to 10^5 edges. Each edge connects two vertices and has an integer weight. For every query [s, t] , we must determine the minimum possible cost of any walk from node s to node t . The key detail is the...

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LeetCode 3074 - Apple Redistribution into Boxes

LeetCode Problem 3074 Difficulty: 🟢 Easy Topics: Array, Greedy, Sorting Solution Problem Understanding The problem asks us to redistribute a collection of apple packs into boxes while using the minimum number of boxes . Each pack apple[i] contains a certain number of apples, and each box capacity[j] can hold up to a certain number of apples. Apples from a single pack can be split across multiple boxes, so we are...

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LeetCode 2976 - Minimum Cost to Convert String I

LeetCode Problem 2976 Difficulty: 🟡 Medium Topics: Array, String, Graph Theory, Shortest Path Solution Problem Understanding This problem asks us to transform one string into another while minimizing the total conversion cost. We are given two strings, source and target , both with the same length. Each position in source must eventually become the corresponding character in target . We are also given a list of allowed character transformations. A...

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LeetCode 2999 - Count the Number of Powerful Integers

LeetCode Problem 2999 Difficulty: 🔴 Hard Topics: Math, String, Dynamic Programming Solution Problem Understanding The problem asks us to count all integers within a given range [start, finish] that satisfy two conditions. First, the integer must end with a specific string s , meaning s is a suffix of the number. Second, each digit in the integer cannot exceed a given limit . For example, if limit is 4 ,...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2740 - Find the Value of the Partition

LeetCode Problem 2740 Difficulty: 🟡 Medium Topics: Array, Sorting Solution LeetCode 2740: Find the Value of the Partition Problem Understanding We are given an array nums containing positive integers. Our task is to divide all elements into two non-empty groups, nums1 and nums2 . Every element must belong to exactly one of the two groups, and neither group may be empty. For a particular partition, the value is defined as:...

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LeetCode 2527 - Find Xor-Beauty of Array

LeetCode Problem 2527 Difficulty: 🟡 Medium Topics: Array, Math, Bit Manipulation Solution Problem Understanding The problem defines a special value called the "effective value" for every possible triplet of indices (i, j, k) in the array: $$((nums[i] \mid nums[j]) & nums[k])$$ where: | is the bitwise OR operator & is the bitwise AND operator The xor-beauty of the array is the XOR of the effective values for all possible triplets....

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LeetCode 2387 - Median of a Row Wise Sorted Matrix

LeetCode Problem 2387 Difficulty: 🟡 Medium Topics: Array, Binary Search, Matrix Solution LeetCode 2387. Median of a Row Wise Sorted Matrix Problem Understanding We are given an m × n matrix grid where every row is already sorted in non-decreasing order. The total number of elements in the matrix is guaranteed to be odd because both m and n are odd. The task is to find the median of all...

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LeetCode 1992 - Find All Groups of Farmland

LeetCode Problem 1992 Difficulty: 🟡 Medium Topics: Array, Depth-First Search, Breadth-First Search, Matrix Solution Problem Understanding In this problem, we are given a binary matrix called land . Each cell contains either: 0 , representing forest land 1 , representing farmland The farmland cells are organized into rectangular groups. Every group is guaranteed to form a perfect rectangle made entirely of 1 s. Additionally, different groups never touch each other...

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LeetCode 1960 - Maximum Product of the Length of Two Palindromic Substrings

LeetCode Problem 1960 Difficulty: 🔴 Hard Topics: Two Pointers, String, Rolling Hash, Hash Function Solution LeetCode 1960 - Maximum Product of the Length of Two Palindromic Substrings Problem Understanding The problem asks us to find two non-overlapping odd-length palindromic substrings whose length product is as large as possible. We are given a string s of length up to 10^5 . We must choose two palindromic substrings: The first occupies indices...

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LeetCode 1963 - Minimum Number of Swaps to Make the String Balanced

LeetCode Problem 1963 Difficulty: 🟡 Medium Topics: Two Pointers, String, Stack, Greedy Solution Problem Understanding The problem asks us to transform a given string of brackets into a balanced string with the minimum number of swaps. The input string s consists of n characters, where n is even, and there are exactly n / 2 opening brackets '[' and n / 2 closing brackets ']' . A string is balanced...

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LeetCode 1913 - Maximum Product Difference Between Two Pairs

LeetCode Problem 1913 Difficulty: 🟢 Easy Topics: Array, Sorting Solution Problem Understanding This problem asks us to find the maximum product difference between two pairs of numbers from a given array. Specifically, given an array nums , we need to select four distinct indices w, x, y, z to form two pairs (nums[w], nums[x]) and (nums[y], nums[z]) . The goal is to maximize the expression (nums[w] * nums[x]) - (nums[y]...

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LeetCode 1782 - Count Pairs Of Nodes

LeetCode Problem 1782 Difficulty: 🔴 Hard Topics: Array, Hash Table, Two Pointers, Binary Search, Graph Theory, Sorting, Counting Solution LeetCode 1782 - Count Pairs Of Nodes Problem Understanding We are given an undirected graph with n nodes and a list of edges. Multiple edges between the same pair of nodes are allowed. For any pair of nodes (a, b) , define incident(a, b) as the number of edges connected to...

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LeetCode 1880 - Check if Word Equals Summation of Two Words

LeetCode Problem 1880 Difficulty: 🟢 Easy Topics: String Solution Problem Understanding The problem asks us to determine if the sum of the numerical values of two words equals the numerical value of a third word. Each word consists of lowercase letters from 'a' to 'j' . Each letter has a letter value , which is its zero-based position in the alphabet ( 'a' -> 0 , 'b' -> 1 ,...

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LeetCode 1867 - Orders With Maximum Quantity Above Average

LeetCode Problem 1867 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem asks us to identify "imbalanced orders" from an OrdersDetails table. Each row represents a product within an order, containing the order_id , product_id , and quantity ordered. An order can have multiple products, meaning multiple rows can share the same order_id . An imbalanced order is defined as one whose maximum quantity of any single product is...

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LeetCode 1851 - Minimum Interval to Include Each Query

LeetCode Problem 1851 Difficulty: 🔴 Hard Topics: Array, Binary Search, Sweep Line, Sorting, Heap (Priority Queue) Solution Problem Understanding The problem gives us a collection of inclusive integer intervals and a list of query values. For every query, we must determine the size of the smallest interval that contains that query value. An interval [left, right] contains a query q if: left <= q <= right The size of an...

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LeetCode 1844 - Replace All Digits with Characters

LeetCode Problem 1844 Difficulty: 🟢 Easy Topics: String Solution Problem Understanding In this problem, we are given a string s where characters at even indices are always lowercase English letters, and characters at odd indices are always digits. The goal is to replace every digit with a new character computed from the character immediately before it. The operation is called shift(c, x) , which means: Start from character c Move...

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LeetCode 3012 - Minimize Length of Array Using Operations

LeetCode Problem 3012 Difficulty: 🟡 Medium Topics: Array, Math, Greedy, Number Theory Solution Problem Understanding The problem gives us a 0-indexed array of positive integers and asks us to repeatedly perform a specific operation to reduce the array's length as much as possible. The operation involves selecting two distinct indices i and j with positive numbers, inserting nums[i] % nums[j] at the end, and removing the original two elements. The...

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LeetCode 2100 - Find Good Days to Rob the Bank

LeetCode Problem 2100 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Prefix Sum Solution Problem Understanding The problem asks us to find all days that are "good" for robbing a bank based on the number of guards on duty over a period of days. You are given an array security where each element represents the number of guards on a specific day, and an integer time that defines a window before...

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LeetCode 2382 - Maximum Segment Sum After Removals

LeetCode Problem 2382 Difficulty: 🔴 Hard Topics: Array, Union-Find, Prefix Sum, Ordered Set Solution Problem Understanding The problem gives us two arrays, nums and removeQueries , both of length n . The nums array contains positive integers. Initially, all elements are present, forming one contiguous segment. Then, elements are removed one by one according to the order defined in removeQueries . After each removal, the array becomes split into one...

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LeetCode 3156 - Employee Task Duration and Concurrent Tasks

LeetCode Problem 3156 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding The problem gives us a table named Tasks , where each row represents a task assigned to an employee. Every task has a start timestamp and an end timestamp. Multiple tasks may overlap in time for the same employee. We need to compute two values for every employee: The total amount of time the employee spent working on tasks....

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LeetCode 2175 - The Change in Global Rankings

LeetCode Problem 2175 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem asks us to determine how the global rankings of national teams change after their points are updated. We are given two database tables: The TeamPoints table contains the current ranking information for each team. Every row includes: team_id , the unique identifier for the team name , the country name points , the current ranking points The...

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LeetCode 2302 - Count Subarrays With Score Less Than K

LeetCode Problem 2302 Difficulty: 🔴 Hard Topics: Array, Binary Search, Sliding Window, Prefix Sum Solution Problem Understanding The problem asks us to count the number of contiguous subarrays of a given array nums whose score is strictly less than a given threshold k . The score of a subarray is defined as the product of its sum and its length. Formally, for a subarray nums[i:j] with length len = j...

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LeetCode 2078 - Two Furthest Houses With Different Colors

LeetCode Problem 2078 Difficulty: 🟢 Easy Topics: Array, Greedy Solution Problem Understanding The problem is asking us to find the maximum distance between two houses that have different colors . You are given a 0-indexed list colors where each element represents the color of a house. The distance between two houses at indices i and j is defined as abs(i - j) - the absolute difference of their indices. The...

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LeetCode 2714 - Find Shortest Path with K Hops

LeetCode Problem 2714 Difficulty: 🔴 Hard Topics: Graph Theory, Heap (Priority Queue), Shortest Path Solution LeetCode 2714 - Find Shortest Path with K Hops Problem Understanding This problem gives us an undirected weighted graph with n nodes and a list of weighted edges. Each edge connects two nodes and has a positive weight. We are also given a source node s , a destination node d , and an integer...

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LeetCode 3340 - Check Balanced String

LeetCode Problem 3340 Difficulty: 🟢 Easy Topics: String Solution Problem Understanding The problem gives us a string num that contains only numeric digits from '0' to '9' . We must determine whether the string is "balanced". A string is considered balanced when the sum of digits located at even indices is equal to the sum of digits located at odd indices. Indexing is zero-based, which means: Index 0 is even...

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LeetCode 3021 - Alice and Bob Playing Flower Game

LeetCode Problem 3021 Difficulty: 🟡 Medium Topics: Math Solution LeetCode 3021 - Alice and Bob Playing Flower Game Problem Understanding The game consists of two flower lanes containing x and y flowers respectively. Alice moves first, and on every turn a player removes exactly one flower from either lane. A very important observation is that the players do not have any meaningful strategic choice. Regardless of which lane a flower...

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LeetCode 2507 - Smallest Value After Replacing With Sum of Prime Factors

LeetCode Problem 2507 Difficulty: 🟡 Medium Topics: Math, Simulation, Number Theory Solution Problem Understanding The problem asks us to repeatedly replace a number n with the sum of its prime factors until it reaches the smallest value it can take. Prime factors should be counted with multiplicity, meaning that if a prime factor divides n multiple times, it is added to the sum as many times as it divides n...

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LeetCode 3034 - Number of Subarrays That Match a Pattern I

LeetCode Problem 3034 Difficulty: 🟡 Medium Topics: Array, Rolling Hash, String Matching, Hash Function Solution Problem Understanding The problem asks us to count how many contiguous subarrays of nums match a given relationship pattern . Instead of comparing exact values, the pattern describes how adjacent numbers should relate to each other. Each value in pattern represents a comparison between two consecutive elements in a subarray: 1 means the next number...

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LeetCode 3003 - Maximize the Number of Partitions After Operations

LeetCode Problem 3003 Difficulty: 🔴 Hard Topics: String, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to take a string s and an integer k and compute the maximum number of partitions we can create from s under a specific set of operations. First, we are allowed to change at most one character in the string to any other lowercase English letter. After that, we repeatedly...

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LeetCode 3047 - Find the Largest Area of Square Inside Two Rectangles

LeetCode Problem 3047 Difficulty: 🟡 Medium Topics: Array, Math, Geometry Solution Problem Understanding The problem asks us to find the largest square that can fit inside the overlapping region of at least two rectangles on a 2D plane. Each rectangle is axis-aligned, meaning its sides are parallel to the x-axis and y-axis. The rectangles are defined by their bottom-left and top-right coordinates, which are given as integer pairs in two...

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LeetCode 3345 - Smallest Divisible Digit Product I

LeetCode Problem 3345 Difficulty: 🟢 Easy Topics: Math, Enumeration Solution Problem Understanding The problem gives us two integers, n and t . We must find the smallest integer greater than or equal to n whose digit product is divisible by t . The digit product of a number is obtained by multiplying all of its digits together. For example: The digit product of 16 is 1 × 6 = 6...

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LeetCode 2566 - Maximum Difference by Remapping a Digit

LeetCode Problem 2566 Difficulty: 🟢 Easy Topics: Math, Greedy Solution Problem Understanding The problem asks us to maximize the difference between two numbers that can be created from a given integer num through a specific remapping operation. We are allowed to choose exactly one digit d1 from 0 through 9 , and replace all occurrences of that digit in num with another digit d2 , which can also be any...

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LeetCode 1895 - Largest Magic Square

LeetCode Problem 1895 Difficulty: 🟡 Medium Topics: Array, Matrix, Prefix Sum Solution Problem Understanding The problem asks us to find the largest magic square inside a given m x n grid. A magic square is a k x k subgrid where the sum of each row, the sum of each column, and the sums of the two main diagonals are all equal. The input is a 2D array of integers,...

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LeetCode 2196 - Create Binary Tree From Descriptions

LeetCode Problem 2196 Difficulty: 🟡 Medium Topics: Array, Hash Table, Tree, Binary Tree Solution Problem Understanding The problem asks us to construct a binary tree from a list of relationships, where each relationship is given as [parent, child, isLeft] . Here, parent is the value of a node, child is the value of its direct descendant, and isLeft indicates whether child is a left child ( 1 ) or a...

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LeetCode 2136 - Earliest Possible Day of Full Bloom

LeetCode Problem 2136 Difficulty: 🔴 Hard Topics: Array, Greedy, Sorting Solution Problem Understanding The problem presents a scenario where we have n flower seeds, each of which requires two phases to bloom: a planting phase and a growth phase. Each seed i takes plantTime[i] full days to plant, which can be spread across non-consecutive days. After planting, the seed requires growTime[i] full days to grow, and only after this period...

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LeetCode 2371 - Minimize Maximum Value in a Grid

LeetCode Problem 2371 Difficulty: 🔴 Hard Topics: Array, Union-Find, Graph Theory, Topological Sort, Sorting, Matrix Solution Problem Understanding The problem presents a matrix grid of size m x n with distinct positive integers . The goal is to transform this matrix so that every element is replaced with another positive integer while maintaining the relative order in each row and column . This means that if an element was larger...

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LeetCode 2201 - Count Artifacts That Can Be Extracted

LeetCode Problem 2201 Difficulty: 🟡 Medium Topics: Array, Hash Table, Simulation Solution Problem Understanding This problem models an excavation process on a square n x n grid. Several rectangular artifacts are buried in the grid, and each artifact occupies one or more cells. Every artifact is described by four integers: (r1, c1) represents the top-left corner (r2, c2) represents the bottom-right corner This means the artifact occupies every cell inside...

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LeetCode 2230 - The Users That Are Eligible for Discount

LeetCode Problem 2230 Difficulty: 🟢 Easy Topics: Database Solution Problem Understanding This problem asks us to identify all users who qualify for a discount based on their purchase history stored in the Purchases table. Each row in the table contains three pieces of information: user_id , the identifier of the user time_stamp , the exact date and time when a purchase occurred amount , the amount paid during that purchase...

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LeetCode 2555 - Maximize Win From Two Segments

LeetCode Problem 2555 Difficulty: 🟡 Medium Topics: Array, Binary Search, Sliding Window Solution Problem Understanding The problem gives us a sorted array prizePositions , where each value represents the position of a prize on the X-axis. Multiple prizes may exist at the same position. We are also given an integer k . We may choose exactly two segments on the number line. Each segment must have length k , meaning...

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LeetCode 2419 - Longest Subarray With Maximum Bitwise AND

LeetCode Problem 2419 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation, Brainteaser Solution Problem Understanding The problem asks us to find the length of the longest subarray within a given array nums such that the bitwise AND of all elements in that subarray is maximized . In simpler terms, we first need to identify the largest possible bitwise AND we can get from any subarray, and then determine the contiguous subarray(s)...

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LeetCode 2594 - Minimum Time to Repair Cars

LeetCode Problem 2594 Difficulty: 🟡 Medium Topics: Array, Binary Search Solution Problem Understanding The problem gives us a list of mechanics, where each mechanic has a specific rank. A mechanic with rank r takes r * n^2 minutes to repair n cars. This means the repair time grows quadratically as the number of assigned cars increases. We are also given an integer cars , representing the total number of cars...

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LeetCode 2642 - Design Graph With Shortest Path Calculator

LeetCode Problem 2642 Difficulty: 🔴 Hard Topics: Graph Theory, Design, Heap (Priority Queue), Shortest Path Solution Problem Understanding The problem asks us to design a graph data structure that supports two operations efficiently: Dynamically adding directed weighted edges. Finding the shortest path cost between two nodes. We are given a directed weighted graph with n nodes labeled from 0 to n - 1 . The graph initially contains a list...

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LeetCode 2855 - Minimum Right Shifts to Sort the Array

LeetCode Problem 2855 Difficulty: 🟢 Easy Topics: Array Solution Problem Understanding The problem gives us a 0-indexed array nums of length n containing distinct positive integers. The goal is to determine the minimum number of right shifts required to sort the array in strictly increasing order. A right shift moves each element at index i to (i + 1) % n , effectively rotating the array one step to the...

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LeetCode 3391 - Design a 3D Binary Matrix with Efficient Layer Tracking

LeetCode Problem 3391 Difficulty: 🟡 Medium Topics: Array, Hash Table, Design, Heap (Priority Queue), Matrix, Ordered Set Solution Problem Understanding The problem asks us to design a data structure that manages a 3D binary matrix of size n x n x n . Every cell initially contains 0 , and we must support three operations efficiently: setCell(x, y, z) sets a specific cell to 1 . unsetCell(x, y, z) sets...

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LeetCode 2514 - Count Anagrams

LeetCode Problem 2514 Difficulty: 🔴 Hard Topics: Hash Table, Math, String, Combinatorics, Counting Solution Problem Understanding The problem asks us to count how many distinct anagram sentences can be formed from a given string s . The input string contains one or more words separated by single spaces. An anagram sentence must preserve the structure of the original sentence. Specifically, the i-th word in the new sentence must be a...

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LeetCode 2422 - Merge Operations to Turn Array Into a Palindrome

LeetCode Problem 2422 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Greedy Solution Problem Understanding The problem asks us to transform a given array of positive integers into a palindrome using the minimum number of operations, where each operation consists of taking two adjacent elements and replacing them with their sum. A palindrome is an array that reads the same forward and backward, so for an array nums , we require...

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LeetCode 3287 - Find the Maximum Sequence Value of Array

LeetCode Problem 3287 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation Solution LeetCode 3287 - Find the Maximum Sequence Value of Array Problem Understanding We are given an array nums and an integer k . We must choose a subsequence of exactly 2 * k elements while preserving the original order of the array. After selecting the subsequence, we split it into two equal halves: The first k selected...

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LeetCode 2286 - Booking Concert Tickets in Groups

LeetCode Problem 2286 Difficulty: 🔴 Hard Topics: Binary Search, Design, Binary Indexed Tree, Segment Tree Solution Problem Understanding The problem asks us to design a ticket reservation system for a concert hall. The hall contains n rows, and each row contains exactly m seats. Seats in every row are numbered from left to right starting at 0 . We must support two different operations: The first operation, gather(k, maxRow) ,...

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LeetCode 2114 - Maximum Number of Words Found in Sentences

LeetCode Problem 2114 Difficulty: 🟢 Easy Topics: Array, String Solution Problem Understanding In this problem, we are given an array of strings called sentences . Each string represents a sentence composed of lowercase English words separated by exactly one space. The problem asks us to determine the maximum number of words that appear in any single sentence. A key detail is how words are separated. The problem guarantees that: There...

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LeetCode 2544 - Alternating Digit Sum

LeetCode Problem 2544 Difficulty: 🟢 Easy Topics: Math Solution Problem Understanding The problem asks us to compute an alternating sum of the digits of a positive integer. The alternation starts from the most significant digit, which always has a positive sign. Every following digit flips the sign from the previous one. For example, if the number is 521 , the calculation becomes: +5 -2 +1 The final answer is 4...

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LeetCode 3204 - Bitwise User Permissions Analysis

LeetCode Problem 3204 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem is asking us to analyze a table of user permissions where each user's permissions are encoded as an integer. Each bit in this integer represents a distinct access level or feature. The goal is to compute two aggregate permission values: common_perms , which represents the set of permissions that every user has, and any_perms , which represents...

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LeetCode 2850 - Minimum Moves to Spread Stones Over Grid

LeetCode Problem 2850 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Matrix, Bitmask Solution Problem Understanding This problem asks us to take a 3x3 grid of integers representing stones in each cell and redistribute them so that every cell contains exactly one stone. Each move consists of moving a stone from one cell to a directly adjacent cell (sharing a side, not a diagonal). The goal is to...

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LeetCode 2825 - Make String a Subsequence Using Cyclic Increments

LeetCode Problem 2825 Difficulty: 🟡 Medium Topics: Two Pointers, String Solution Problem Understanding The problem gives us two lowercase strings, str1 and str2 . We are allowed to perform at most one global operation on str1 . During this operation, we may choose any subset of indices in str1 , and increment the character at each chosen index by one alphabetically. The increment is cyclic, meaning 'z' becomes 'a' ....

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LeetCode 3181 - Maximum Total Reward Using Operations II

LeetCode Problem 3181 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation Solution Problem Understanding The problem gives us an array rewardValues , where each element represents a reward we may choose exactly once. We begin with a total reward x = 0 , and we are allowed to repeatedly pick an unmarked element only if its value is strictly greater than the current total reward. Once we choose a...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2700 - Differences Between Two Objects

LeetCode Problem 2700 Difficulty: 🟡 Medium Topics: — Solution That is a long-form reference document with multiple substantial sections, complete Python and Go implementations, detailed walkthroughs, and worked examples. To keep formatting quality high and avoid truncation, I will provide it in a structured document format. Please confirm one detail before I begin: should I assume the standard LeetCode JavaScript-style signature for this problem and adapt it idiomatically for Python/Go...

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LeetCode 2715 - Timeout Cancellation

LeetCode Problem 2715 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding This problem asks us to implement a cancellable delayed function execution mechanism. Essentially, you are given a function fn , an array of arguments args , and a timeout t in milliseconds. Your task is to return a cancel function cancelFn that, when invoked, can prevent the execution of fn if it has not already occurred. The function fn...

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LeetCode 2183 - Count Array Pairs Divisible by K

LeetCode Problem 2183 Difficulty: 🔴 Hard Topics: Array, Hash Table, Math, Counting, Number Theory Solution Problem Understanding The problem gives us an integer array nums and an integer k . We must count how many index pairs (i, j) satisfy two conditions: i < j nums[i] * nums[j] is divisible by k In other words, for every pair of distinct elements in the array, we check whether their product contains...

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LeetCode 2102 - Sequentially Ordinal Rank Tracker

LeetCode Problem 2102 Difficulty: 🔴 Hard Topics: Design, Heap (Priority Queue), Data Stream, Ordered Set Solution Problem Understanding The problem asks us to design a data structure that continuously tracks scenic locations ranked by two rules: A higher score means a better location. If two locations have the same score, the lexicographically smaller name is considered better. The system supports two operations: add(name, score) inserts a new location. get() returns...

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LeetCode 2974 - Minimum Number Game

LeetCode Problem 2974 Difficulty: 🟢 Easy Topics: Array, Sorting, Heap (Priority Queue), Simulation Solution Problem Understanding The problem gives us an integer array nums with an even number of elements. We repeatedly simulate a game between Alice and Bob until the array becomes empty. In each round, the following sequence happens: Alice removes the smallest remaining number. Bob removes the next smallest remaining number. Bob appends his removed number to...

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LeetCode 2108 - Find First Palindromic String in the Array

LeetCode Problem 2108 Difficulty: 🟢 Easy Topics: Array, Two Pointers, String Solution Problem Understanding The problem asks us to examine an array of strings, words , and identify the first string that is a palindrome. A palindrome is a string that reads the same forward and backward. In other words, the first character matches the last, the second matches the second-to-last, and so on. If no string in the array...

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LeetCode 2275 - Largest Combination With Bitwise AND Greater Than Zero

LeetCode Problem 2275 Difficulty: 🟡 Medium Topics: Array, Hash Table, Bit Manipulation, Counting Solution Problem Understanding The problem asks us to find the largest possible group of numbers from the candidates array such that the bitwise AND of every number in that group is greater than 0 . A bitwise AND operation only keeps bits that are set to 1 in every participating number. For example: 6 = 110 14...

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LeetCode 3332 - Maximum Points Tourist Can Earn

LeetCode Problem 3332 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Matrix Solution Problem Understanding The problem asks us to maximize the points a tourist can earn over a fixed number of days, k , while visiting n cities. Each day, the tourist has a choice: either stay in the current city and earn points according to stayScore for that day and city, or travel to another city and earn points...

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LeetCode 2561 - Rearranging Fruits

LeetCode Problem 2561 Difficulty: 🔴 Hard Topics: Array, Hash Table, Greedy, Sort Solution Problem Understanding This problem gives us two arrays, basket1 and basket2 , where each element represents the cost of a fruit in a basket. Both baskets contain exactly n fruits. Our goal is to make the two baskets equal, where equality means that after sorting both arrays, they contain exactly the same multiset of values. We are...

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LeetCode 3087 - Find Trending Hashtags

LeetCode Problem 3087 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem asks us to find the top 3 trending hashtags from a table of tweets for a specific month, February 2024. Each tweet contains exactly one hashtag. The input is represented by a Tweets table with columns user_id , tweet_id , tweet , and tweet_date . The tweet_id is unique for each row, and tweet contains a string...

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LeetCode 1898 - Maximum Number of Removable Characters

LeetCode Problem 1898 Difficulty: 🟡 Medium Topics: Array, Two Pointers, String, Binary Search Solution Problem Understanding The problem gives us two strings, s and p , and a list of indices removable . The string p is guaranteed to be a subsequence of s , meaning all characters in p appear in s in the same order, though not necessarily consecutively. The array removable represents positions in s that we...

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LeetCode 3137 - Minimum Number of Operations to Make Word K-Periodic

LeetCode Problem 3137 Difficulty: 🟡 Medium Topics: Hash Table, String, Counting Solution Problem Understanding The problem asks us to transform a given string word of length n into a k-periodic string using the minimum number of operations. A string is k-periodic if it can be formed by repeating a substring s of length k multiple times. Each operation allows us to pick two substrings of length k that start at...

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LeetCode 3189 - Minimum Moves to Get a Peaceful Board

LeetCode Problem 3189 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting, Counting Sort Solution Problem Understanding In this problem, we are given the positions of n rooks placed on an n x n chessboard. Each rook is represented as a pair [xi, yi] , where xi is the row index and yi is the column index. A peaceful board is defined as a board where: Every row contains exactly one rook...

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LeetCode 2172 - Maximum AND Sum of Array

LeetCode Problem 2172 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution LeetCode 2172 - Maximum AND Sum of Array Problem Understanding This problem asks us to distribute a set of integers into numbered slots in a way that maximizes a scoring function based on bitwise AND operations. We are given: An integer array nums A number of slots, numSlots Each slot is numbered from 1 to numSlots...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2794 - Create Object from Two Arrays

LeetCode Problem 2794 Difficulty: 🟢 Easy Topics: — Solution LeetCode 2794 - Create Object from Two Arrays Problem Understanding The problem provides two arrays, keysArr and valuesArr , which always have the same length. Each position in the arrays represents a potential key-value pair. The element at index i in keysArr should become the key, and the element at index i in valuesArr should become the corresponding value. The goal...

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LeetCode 1973 - Count Nodes Equal to Sum of Descendants

LeetCode Problem 1973 Difficulty: 🟡 Medium Topics: Tree, Depth-First Search, Binary Tree Solution Problem Understanding This problem asks us to analyze a binary tree and count how many nodes satisfy a specific property: the value of the node equals the sum of all its descendants. A descendant of a node is any node that lies in the subtree rooted at that node excluding the node itself. For example, if a...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2259 - Remove Digit From Number to Maximize Result

LeetCode Problem 2259 Difficulty: 🟢 Easy Topics: String, Greedy, Enumeration Solution LeetCode 2259 - Remove Digit From Number to Maximize Result Problem Understanding The problem gives us a string called number , which represents a positive integer, and a character digit , which is guaranteed to appear at least once inside number . Our task is to remove exactly one occurrence of digit from the string so that the resulting...

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LeetCode 3349 - Adjacent Increasing Subarrays Detection I

LeetCode Problem 3349 Difficulty: 🟢 Easy Topics: Array Solution Problem Understanding The problem gives us an integer array nums and an integer k . We need to determine whether the array contains two adjacent subarrays, each of length k , such that both subarrays are strictly increasing. A subarray is strictly increasing if every element is larger than the one before it. For example, [2, 5, 7] is strictly increasing...

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LeetCode 3082 - Find the Sum of the Power of All Subsequences

LeetCode Problem 3082 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming Solution Problem Understanding You are given an array nums and an integer k . For every subsequence of nums , we define its power as the number of subsequences inside it whose sum equals k . The task is to compute the total power across all subsequences of the original array. The wording is initially confusing because we are dealing...

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LeetCode 2040 - Kth Smallest Product of Two Sorted Arrays

LeetCode Problem 2040 Difficulty: 🔴 Hard Topics: Array, Binary Search Solution Problem Understanding The problem asks for the k-th smallest product that can be formed by multiplying one element from the sorted array nums1 with one element from the sorted array nums2 . Both arrays may contain negative numbers, zeros, and positive numbers. The value of k is 1-based, meaning k = 1 corresponds to the smallest product overall. The...

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LeetCode 3363 - Find the Maximum Number of Fruits Collected

LeetCode Problem 3363 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Matrix Solution Problem Understanding This problem asks us to maximize the total number of fruits collected by three children traversing a square grid of rooms, each with a certain number of fruits. The grid has dimensions n x n , and the fruits are given in a 2D array fruits[i][j] . The three children start at fixed corners: (0,0) ,...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2534 - Time Taken to Cross the Door

LeetCode Problem 2534 Difficulty: 🔴 Hard Topics: Array, Queue, Simulation Solution Problem Understanding This problem asks us to simulate how people pass through a single door over time while following a specific priority policy. Every person arrives at a certain second and wants to either enter or exit. Only one person may use the door per second, and when multiple people are waiting, the rules determine who gets priority. The...

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LeetCode 3298 - Count Substrings That Can Be Rearranged to Contain a String II

LeetCode Problem 3298 Difficulty: 🔴 Hard Topics: Hash Table, String, Sliding Window Solution Problem Understanding We are given two strings, word1 and word2 . We need to count how many substrings of word1 are considered valid. A substring is valid if its characters can be rearranged so that word2 becomes a prefix of the rearranged string. This condition is equivalent to saying that the substring must contain at least all...

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LeetCode 2609 - Find the Longest Balanced Substring of a Binary String

LeetCode Problem 2609 Difficulty: 🟢 Easy Topics: String Solution Problem Understanding The problem gives us a binary string s , which means the string contains only the characters '0' and '1' . We need to find the length of the longest substring that is considered balanced. A substring is balanced when two conditions are satisfied: All zeroes appear before all ones. The number of zeroes equals the number of ones....

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LeetCode 3228 - Maximum Number of Operations to Move Ones to the End

LeetCode Problem 3228 Difficulty: 🟡 Medium Topics: String, Greedy, Counting Solution Problem Understanding The problem gives us a binary string s , consisting only of characters '0' and '1' . We are allowed to repeatedly perform a specific operation: Find an index i such that: s[i] == '1' s[i + 1] == '0' Move that '1' to the right until it either: reaches the end of the string, or stops...

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LeetCode 3019 - Number of Changing Keys

LeetCode Problem 3019 Difficulty: 🟢 Easy Topics: String Solution Problem Understanding The problem asks us to determine how many times a user changes keys while typing a string s . A change of key occurs when the current character typed differs in its lowercase form from the previous character typed. Importantly, differences in case (uppercase vs lowercase) do not count as a key change because modifiers like shift or caps...

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LeetCode 2765 - Longest Alternating Subarray

LeetCode Problem 2765 Difficulty: 🟢 Easy Topics: Array, Enumeration Solution LeetCode 2765 - Longest Alternating Subarray Problem Understanding This problem asks us to find the longest contiguous subarray that follows a very specific alternating pattern. Given an integer array nums , we need to identify subarrays where: The subarray length is at least 2 . The second element is exactly one greater than the first element. Every subsequent difference alternates...

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LeetCode 2075 - Decode the Slanted Ciphertext

LeetCode Problem 2075 Difficulty: 🟡 Medium Topics: String, Simulation Solution Problem Understanding The problem requires decoding a string that was encoded using a slanted transposition cipher . In this cipher, the original text is written diagonally in a grid with a fixed number of rows. Specifically, the placement starts at the top-left and moves down and to the right in a zig-zag manner. After filling the grid, the encoded string...

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LeetCode 1897 - Redistribute Characters to Make All Strings Equal

LeetCode Problem 1897 Difficulty: 🟢 Easy Topics: Hash Table, String, Counting Solution Problem Understanding The problem asks whether it is possible to make all strings in the input array words equal by redistributing characters between them. Specifically, in one operation, you can pick any character from one string and move it to another string at any position. The goal is to determine if, after potentially many such operations, every string...

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LeetCode 1937 - Maximum Number of Points with Cost

LeetCode Problem 1937 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Matrix Solution Problem Understanding The problem gives us an m x n matrix called points . We must choose exactly one cell from every row. The value of the chosen cell is added to our score. However, there is a movement penalty between consecutive rows. If we choose column c1 in row r and column c2 in row r +...

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LeetCode 3214 - Year on Year Growth Rate

LeetCode Problem 3214 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding This problem asks us to compute the year-on-year, often abbreviated as YoY, growth rate of total spending for every product in the user_transactions table. Each row in the input table represents a single transaction. A transaction contains four important pieces of information: The unique transaction ID The product ID The amount spent in that transaction The transaction timestamp The...

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LeetCode 2679 - Sum in a Matrix

LeetCode Problem 2679 Difficulty: 🟡 Medium Topics: Array, Sorting, Heap (Priority Queue), Matrix, Simulation Solution Problem Understanding The problem gives us a 2D integer matrix nums . Each row contains several integers, and we repeatedly perform a special removal process until every element has been removed. During each operation, we do two things: From every row, remove the largest remaining element. Among all removed elements from this round, take the...

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LeetCode 3142 - Check if Grid Satisfies Conditions

LeetCode Problem 3142 Difficulty: 🟢 Easy Topics: Array, Matrix Solution Problem Understanding The problem gives us a two dimensional matrix called grid with m rows and n columns. We must verify whether every cell satisfies two separate rules. The first rule applies vertically. For every cell, if there is a cell directly below it, both values must be equal. In other words: grid[i][j] == grid[i + 1][j] The second rule...

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LeetCode 2346 - Compute the Rank as a Percentage

LeetCode Problem 2346 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem provides a database table named Students , where each row represents a student and contains three fields: student_id , the unique identifier for the student department_id , the department the student belongs to mark , the student's exam score The goal is to compute each student's rank percentage inside their department. The ranking is based on descending...

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LeetCode 2062 - Count Vowel Substrings of a String

LeetCode Problem 2062 Difficulty: 🟢 Easy Topics: Hash Table, String Solution Problem Understanding The problem requires counting the number of vowel substrings in a given string word . A substring is any contiguous sequence of characters within the string. A vowel substring is defined as a substring that contains only vowels ( 'a' , 'e' , 'i' , 'o' , 'u' ) and must include all five vowels at least...

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LeetCode 2710 - Remove Trailing Zeros From a String

LeetCode Problem 2710 Difficulty: 🟢 Easy Topics: String Solution Problem Understanding The problem asks us to remove all trailing zeros from a string representing a positive integer. The input num is a string consisting only of digits with no leading zeros, and the length of the string is between 1 and 1000. The output should be a string representation of the same integer but without any zeros at the end....

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LeetCode 2724 - Sort By

LeetCode Problem 2724 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding This problem asks us to sort an array using a custom sorting rule. Instead of sorting elements directly by their own value, we are given a function fn that transforms each element into a numeric value, and that numeric value determines the order. In other words, every element in arr is assigned a sort key by calling fn(element) ....

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LeetCode 2572 - Count the Number of Square-Free Subsets

LeetCode Problem 2572 Difficulty: 🟡 Medium Topics: Array, Math, Dynamic Programming, Bit Manipulation, Number Theory, Bitmask Solution Problem Understanding The problem asks us to count all non-empty subsets of a given array nums such that the product of the elements in each subset is square-free . A square-free integer is an integer not divisible by the square of any prime greater than 1. In other words, in its prime factorization,...

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LeetCode 2982 - Find Longest Special Substring That Occurs Thrice II

LeetCode Problem 2982 Difficulty: 🟡 Medium Topics: Hash Table, String, Binary Search, Sliding Window, Counting Solution LeetCode 2982 - Find Longest Special Substring That Occurs Thrice II Problem Understanding The problem asks us to find the maximum length of a special substring that appears at least three times in the given string. A substring is considered special if it consists entirely of a single repeated character. Examples include: "a" "bbb"...

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LeetCode 3377 - Digit Operations to Make Two Integers Equal

LeetCode Problem 3377 Difficulty: 🟡 Medium Topics: Math, Graph Theory, Heap (Priority Queue), Number Theory, Shortest Path Solution Problem Understanding The problem asks us to transform one integer n into another integer m by repeatedly modifying individual digits of n . At each step, we can increase a digit that is not 9 or decrease a digit that is not 0. However, there is a strict constraint: n cannot ever...

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LeetCode 3374 - First Letter Capitalization II

LeetCode Problem 3374 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding This problem asks us to transform text stored in a database table while preserving the original formatting structure. The table user_content contains two columns: a unique content_id and a content_text string. For every row, we must generate a new version of the text where each word follows title case formatting rules. More specifically, every word must be converted so...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2349 - Design a Number Container System

LeetCode Problem 2349 Difficulty: 🟡 Medium Topics: Hash Table, Design, Heap (Priority Queue), Ordered Set Solution LeetCode 2349 - Design a Number Container System Problem Understanding The problem asks us to design a data structure that supports two operations efficiently: Assign a number to a given index. Find the smallest index currently assigned to a given number. The important detail is that the change(index, number) operation can both insert and...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2829 - Determine the Minimum Sum of a k-avoiding Array

LeetCode Problem 2829 Difficulty: 🟡 Medium Topics: Math, Greedy Solution Problem Understanding The problem asks us to construct an array of n distinct positive integers such that no two elements in the array sum to a given integer k . This type of array is called k-avoiding . Among all possible k-avoiding arrays of length n , we are asked to find the minimum possible sum of its elements. The...

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LeetCode 1915 - Number of Wonderful Substrings

LeetCode Problem 1915 Difficulty: 🟡 Medium Topics: Hash Table, String, Bit Manipulation, Prefix Sum Solution LeetCode 1915, Number of Wonderful Substrings Problem Understanding The problem asks us to count how many non-empty substrings of a given string are considered "wonderful". A substring is wonderful if at most one character appears an odd number of times inside that substring. The string only contains characters from 'a' to 'j' , which means...

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LeetCode 2582 - Pass the Pillow

LeetCode Problem 2582 Difficulty: 🟢 Easy Topics: Math, Simulation Solution Problem Understanding The problem describes a line of n people, numbered sequentially from 1 to n . Initially, person 1 holds a pillow. Every second, the pillow is passed to the adjacent person. The direction of passing changes whenever the pillow reaches either end of the line. In other words, the pillow moves forward from person 1 toward person n...

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LeetCode 2437 - Number of Valid Clock Times

LeetCode Problem 2437 Difficulty: 🟢 Easy Topics: String, Enumeration Solution Problem Understanding The problem asks us to determine the number of valid times that can be formed from a partially known digital clock string of the format "hh:mm" , where unknown digits are represented by '?' . Each '?' can be replaced with any digit from 0 to 9 , but the resulting hour ( hh ) must be in...

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LeetCode 3352 - Count K-Reducible Numbers Less Than N

LeetCode Problem 3352 Difficulty: 🔴 Hard Topics: Math, String, Dynamic Programming, Combinatorics Solution Problem Understanding The problem asks us to count the number of positive integers less than n (where n is given in binary as a string s ) that are k-reducible . An integer x is k-reducible if applying the operation "replace x with the count of set bits in its binary representation" at most k times eventually...

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LeetCode 3393 - Count Paths With the Given XOR Value

LeetCode Problem 3393 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Bit Manipulation, Matrix Solution Problem Understanding The problem gives us an m x n grid where each cell contains a small integer value. We start at the top left corner (0, 0) and must reach the bottom right corner (m - 1, n - 1) by moving only right or down. Along every path, we compute the XOR of all...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2926 - Maximum Balanced Subsequence Sum

LeetCode Problem 2926 Difficulty: 🔴 Hard Topics: Array, Binary Search, Dynamic Programming, Binary Indexed Tree, Segment Tree Solution Problem Understanding This problem asks us to find the maximum sum of a balanced subsequence from a given integer array nums . A subsequence is a selection of elements from the array in their original order, possibly skipping elements. A subsequence is balanced if, for every pair of consecutive indices i and...

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LeetCode 2327 - Number of People Aware of a Secret

LeetCode Problem 2327 Difficulty: 🟡 Medium Topics: Dynamic Programming, Queue, Simulation Solution Problem Understanding The problem describes how a secret spreads over time. On day 1 , exactly one person knows the secret. Every person who learns the secret behaves according to two rules: They must wait delay days before they can begin sharing the secret. They forget the secret after forget days, and once they forget it, they can...

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LeetCode 2691 - Immutability Helper

LeetCode Problem 2691 Difficulty: 🔴 Hard Topics: — Solution Problem Understanding This problem is asking us to implement an immutability helper for JSON-like objects in JavaScript. Specifically, we need to create a class ImmutableHelper that allows users to "mutate" a proxy version of the object without affecting the original object. The produce method accepts a mutator function, which may modify the proxied object as if it were mutable. After the...

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LeetCode 2383 - Minimum Hours of Training to Win a Competition

LeetCode Problem 2383 Difficulty: 🟢 Easy Topics: Array, Greedy Solution Problem Understanding The problem gives us two starting values, initialEnergy and initialExperience , which represent the player's stats before entering a sequence of competitions. We are also given two arrays, energy and experience , where each index corresponds to an opponent. To defeat opponent i , the player must satisfy two strict conditions at the moment the fight begins: Current...

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LeetCode 2155 - All Divisions With the Highest Score of a Binary Array

LeetCode Problem 2155 Difficulty: 🟡 Medium Topics: Array Solution Problem Understanding The problem gives us a binary array nums , meaning every element is either 0 or 1 . We are allowed to divide the array at any index i where 0 <= i <= n , and that division creates two parts: The left part contains elements from index 0 to i - 1 The right part contains elements...

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LeetCode 3049 - Earliest Second to Mark Indices II

LeetCode Problem 3049 Difficulty: 🔴 Hard Topics: Array, Binary Search, Greedy, Heap (Priority Queue) Solution Problem Understanding We are given two arrays: nums , where nums[i] represents the initial value associated with index i + 1 changeIndices , where at second s , we are allowed to perform a special operation on index changeIndices[s] Every index in nums starts as unmarked. Our goal is to mark every index as early...

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LeetCode 3041 - Maximize Consecutive Elements in an Array After Modification

LeetCode Problem 3041 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Sorting Solution Problem Understanding The problem is asking us to maximize the number of consecutive integers we can select from an array after we are allowed to increase any element by at most 1 . The input array nums contains positive integers and can have up to 10^5 elements, with each element ranging from 1 to 10^6 . The output...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2182 - Construct String With Repeat Limit

LeetCode Problem 2182 Difficulty: 🟡 Medium Topics: Hash Table, String, Greedy, Heap (Priority Queue), Counting Solution Problem Understanding The problem asks us to construct a string from the characters of a given string s under a specific constraint: no character can appear more than repeatLimit times consecutively. The goal is not just to create any valid string but to produce the lexicographically largest one possible. Lexicographic ordering is similar to...

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LeetCode 2971 - Find Polygon With the Largest Perimeter

LeetCode Problem 2971 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting, Prefix Sum Solution LeetCode 2971 - Find Polygon With the Largest Perimeter Problem Understanding The problem gives us an array nums containing positive integers. Each integer represents a potential side length that we may use when constructing a polygon. A polygon must have at least three sides. The key geometric property we are given is that if the side lengths...

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LeetCode 2266 - Count Number of Texts

LeetCode Problem 2266 Difficulty: 🟡 Medium Topics: Hash Table, Math, String, Dynamic Programming Solution Problem Understanding The problem requires determining how many possible text messages Alice could have sent given a sequence of digit key presses received by Bob. Each digit from '2' to '9' maps to a set of letters on a phone keypad. Pressing a key multiple times selects a different letter on that key. For example, pressing...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1856 - Maximum Subarray Min-Product

LeetCode Problem 1856 Difficulty: 🟡 Medium Topics: Array, Stack, Monotonic Stack, Prefix Sum Solution Problem Understanding The problem asks us to find the maximum min-product of any contiguous subarray of a given integer array nums . The min-product of a subarray is defined as the minimum value in that subarray multiplied by the sum of all elements in that subarray . We are asked to return this maximum value modulo...

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LeetCode 3078 - Match Alphanumerical Pattern in Matrix I

LeetCode Problem 3078 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Matrix Solution LeetCode 3078 - Match Alphanumerical Pattern in Matrix I Problem Understanding This problem asks us to search for a rectangular submatrix inside a larger integer matrix, where the submatrix follows a pattern described by digits and lowercase letters. The input consists of: board , a 2D matrix of integers from 0 to 9 pattern , a 2D...

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LeetCode 3033 - Modify the Matrix

LeetCode Problem 3033 Difficulty: 🟢 Easy Topics: Array, Matrix Solution Problem Understanding The problem is asking us to take a given m x n matrix, potentially containing -1 values, and produce a modified matrix in which each -1 is replaced by the maximum value in its respective column. The input matrix is guaranteed to have at least one non-negative integer in each column, which ensures that a maximum value can...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2317 - Maximum XOR After Operations

LeetCode Problem 2317 Difficulty: 🟡 Medium Topics: Array, Math, Bit Manipulation Solution Problem Understanding The problem gives us an integer array nums , and we may perform a special operation any number of times. In one operation, we choose an index i and any non-negative integer x , then replace: nums[i] = nums[i] AND (nums[i] XOR x) Our goal is to maximize the bitwise XOR of all elements in the...

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LeetCode 3136 - Valid Word

LeetCode Problem 3136 Difficulty: 🟢 Easy Topics: String Solution Problem Understanding The problem asks us to determine whether a given string qualifies as a "valid word" according to four specific rules. First, the word must contain at least 3 characters. Any string shorter than 3 is automatically invalid. Second, every character in the string must be either: A lowercase English letter An uppercase English letter A digit from 0 to...

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LeetCode 2895 - Minimum Processing Time

LeetCode Problem 2895 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting Solution Problem Understanding This problem gives us two arrays: processorTime , where each value represents the time when a processor becomes available tasks , where each value represents how long a task takes to execute Each processor has exactly 4 cores, and each core can execute exactly one task. Since there are n processors and each processor has 4 cores,...

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LeetCode 3066 - Minimum Operations to Exceed Threshold Value II

LeetCode Problem 3066 Difficulty: 🟡 Medium Topics: Array, Heap (Priority Queue), Simulation Solution Problem Understanding This problem asks us to repeatedly combine the two smallest elements of an array nums until all elements are greater than or equal to a threshold value k . The combination operation is not a simple sum, but a formula: min(x, y) * 2 + max(x, y) . Essentially, this operation increases the smaller numbers...

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LeetCode 2343 - Query Kth Smallest Trimmed Number

LeetCode Problem 2343 Difficulty: 🟡 Medium Topics: Array, String, Divide and Conquer, Sorting, Heap (Priority Queue), Radix Sort, Quickselect Solution Problem Understanding This problem provides a list of numbers represented as strings, all of equal length. The task is to answer multiple queries, where each query asks for the index of the k-th smallest number after trimming every number in the list to its last trimi digits. Importantly, if two...

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LeetCode 2673 - Make Costs of Paths Equal in a Binary Tree

LeetCode Problem 2673 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Greedy, Tree, Binary Tree Solution Edit LeetCode 2673 - Make Costs of Paths Equal in a Binary Tree Problem Understanding This problem gives us a perfect binary tree with n nodes, where each node has an associated cost. The tree follows a strict indexing rule: node i has a left child at 2 * i and a right child at...

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LeetCode 2939 - Maximum Xor Product

LeetCode Problem 2939 Difficulty: 🟡 Medium Topics: Math, Greedy, Bit Manipulation Solution That will be quite long and detailed given your required structure and depth. To ensure quality and avoid truncation, I will provide it in a carefully structured, complete editorial format. Before I begin, one important clarification: for LeetCode 2939 - Maximum Xor Product , there are two valid optimal explanations commonly used: Greedy bit construction with balancing intuition...

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LeetCode 2350 - Shortest Impossible Sequence of Rolls

LeetCode Problem 2350 Difficulty: 🔴 Hard Topics: Array, Hash Table, Greedy Solution Here is a complete, detailed technical solution guide for LeetCode 2350 - Shortest Impossible Sequence of Rolls , following your requested format precisely. Problem Understanding The problem asks us to determine the length of the shortest sequence of dice rolls that cannot be found as a subsequence within a given list of dice rolls. We are given an...

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LeetCode 2168 - Unique Substrings With Equal Digit Frequency

LeetCode Problem 2168 Difficulty: 🟡 Medium Topics: Hash Table, String, Rolling Hash, Counting, Hash Function Solution Problem Understanding The problem gives us a string s consisting only of digits from '0' to '9' . We must count how many distinct substrings satisfy a special condition: Every digit that appears in the substring must appear the same number of times. A substring is a contiguous portion of the string. The substring...

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LeetCode 3384 - Team Dominance by Pass Success

LeetCode Problem 3384 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding This problem asks us to compute a dominance score for each football team across two halves of a match, based on passing outcomes. The input is represented using two database tables, Teams and Passes . The Teams table maps every player to exactly one team. Since player_id is unique, each player belongs to only one team for the duration...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3217 - Delete Nodes From Linked List Present in Array

LeetCode Problem 3217 Difficulty: 🟡 Medium Topics: Array, Hash Table, Linked List Solution Problem Understanding This problem asks us to modify a singly linked list by removing all nodes whose values appear in a given array nums . The input consists of two elements: an array of integers nums and the head of a linked list. Each node in the linked list contains an integer value and a pointer to...

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LeetCode 1979 - Find Greatest Common Divisor of Array

LeetCode Problem 1979 Difficulty: 🟢 Easy Topics: Array, Math, Number Theory Solution Problem Understanding The problem asks us to compute the greatest common divisor (GCD) of two specific values derived from the input array nums : the smallest element in the array and the largest element in the array. In other words, we are not computing the GCD of all elements, nor are we looking for pairwise relationships across the...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2604 - Minimum Time to Eat All Grains

LeetCode Problem 2604 Difficulty: 🔴 Hard Topics: Array, Two Pointers, Binary Search, Sorting Solution Problem Understanding The problem asks us to determine the minimum time needed for all hens to eat all grains when both hens and grains are located on a one-dimensional line. Each hen can move left or right by 1 unit per second and can eat multiple grains, but only when occupying the same position as the...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2402 - Meeting Rooms III

LeetCode Problem 2402 Difficulty: 🔴 Hard Topics: Array, Hash Table, Sorting, Heap (Priority Queue), Simulation Solution Problem Understanding The problem is about scheduling meetings into a fixed number of rooms, where each meeting has a unique start time and a defined duration. We have n rooms numbered from 0 to n - 1 , and we are given a list of meetings represented as [start, end) intervals. The task is...

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LeetCode 3169 - Count Days Without Meetings

LeetCode Problem 3169 Difficulty: 🟡 Medium Topics: Array, Sorting Solution LeetCode 3169 - Count Days Without Meetings Problem Understanding The problem gives us a total number of working days, numbered from 1 to days , along with a list of meeting intervals. Each interval [start, end] represents a meeting that occupies every day from start through end , inclusive. Our task is to determine how many days remain completely free,...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2115 - Find All Possible Recipes from Given Supplies

LeetCode Problem 2115 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Graph Theory, Topological Sort Solution Problem Understanding This problem asks us to determine which recipes can be created when we start with a set of available supplies and are allowed to recursively create additional recipes. Each recipe has a list of required ingredients. Some ingredients are basic supplies that we already own, while others may themselves be recipes. Once...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2617 - Minimum Number of Visited Cells in a Grid

LeetCode Problem 2617 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Stack, Breadth-First Search, Union-Find, Heap (Priority Queue), Matrix, Monotonic Stack Solution Problem Understanding The problem asks us to determine the minimum number of cells we need to visit in order to reach the bottom-right corner of a given m x n grid. Each cell (i, j) contains a number grid[i][j] representing the maximum number of steps we can move right...

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LeetCode 2374 - Node With Highest Edge Score

LeetCode Problem 2374 Difficulty: 🟡 Medium Topics: Hash Table, Graph Theory Solution Problem Understanding The problem asks us to analyze a directed graph where each node has exactly one outgoing edge, represented by the array edges . Each index i represents a node, and edges[i] represents a directed edge from node i to node edges[i] . We are required to calculate the edge score for each node, defined as the...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3354 - Make Array Elements Equal to Zero

LeetCode Problem 3354 Difficulty: 🟢 Easy Topics: Array, Simulation, Prefix Sum Solution Problem Understanding The problem gives us an integer array nums , where some elements may already be zero and others are positive integers. We must choose a starting index curr such that nums[curr] == 0 , and also choose an initial movement direction, either left or right. Once the process begins, we repeatedly follow a set of movement...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2927 - Distribute Candies Among Children III

LeetCode Problem 2927 Difficulty: 🔴 Hard Topics: Math, Combinatorics Solution LeetCode 2927 - Distribute Candies Among Children III Problem Understanding We are given two integers, n and limit . There are exactly three children, and we want to distribute all n candies among them. If we let the number of candies received by the three children be: $$x_1,\ x_2,\ x_3$$ then the distribution must satisfy: $$x_1 + x_2 + x_3...

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LeetCode 3122 - Minimum Number of Operations to Satisfy Conditions

LeetCode Problem 3122 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Matrix Solution Problem Understanding The problem presents a two-dimensional matrix grid of size m x n with integer values in the range 0 to 9. The task is to transform this matrix using the minimum number of operations, where each operation allows you to change the value of any cell to any non-negative integer. After all operations, the matrix must...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2418 - Sort the People

LeetCode Problem 2418 Difficulty: 🟢 Easy Topics: Array, Hash Table, String, Sorting Solution LeetCode 2418, Sort the People Problem Understanding This problem gives us two arrays of equal length: names[i] represents the name of a person heights[i] represents the height of that same person The two arrays are aligned by index, meaning the person at index i has both the name names[i] and the height heights[i] . The goal is...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2193 - Minimum Number of Moves to Make Palindrome

LeetCode Problem 2193 Difficulty: 🔴 Hard Topics: Two Pointers, String, Greedy, Binary Indexed Tree Solution LeetCode 2193 - Minimum Number of Moves to Make Palindrome Problem Understanding This problem asks us to transform a given string into a palindrome using the minimum number of adjacent swaps. A palindrome is a string that reads the same forward and backward. For example, "abba" and "racecar" are palindromes. The only operation allowed is...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3347 - Maximum Frequency of an Element After Performing Operations II

LeetCode Problem 3347 Difficulty: 🔴 Hard Topics: Array, Binary Search, Sliding Window, Sorting, Prefix Sum Solution LeetCode 3347 - Maximum Frequency of an Element After Performing Operations II Problem Understanding The problem gives us an integer array nums , along with two integers, k and numOperations . We are allowed to perform exactly numOperations operations. In each operation: We must choose an index that has not been used before. We...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2899 - Last Visited Integers

LeetCode Problem 2899 Difficulty: 🟢 Easy Topics: Array, Simulation Solution Problem Understanding The problem gives us an integer array nums that contains either positive integers or the value -1 . We process the array from left to right while maintaining two conceptual arrays: seen , which stores previously encountered positive integers ans , which stores the answers for each -1 Whenever we encounter a positive integer, we insert it at...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1947 - Maximum Compatibility Score Sum

LeetCode Problem 1947 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding The problem is asking us to optimally pair students with mentors such that the sum of their compatibility scores is maximized. Each student and each mentor has answered n yes/no questions represented by 0 s and 1 s. A student-mentor pair's compatibility score is the count of matching answers. For instance, if a...

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LeetCode 2717 - Semi-Ordered Permutation

LeetCode Problem 2717 Difficulty: 🟢 Easy Topics: Array, Simulation Solution LeetCode 2717 - Semi-Ordered Permutation Problem Understanding The problem gives us a permutation nums of length n . A permutation means the array contains every integer from 1 to n exactly once. A permutation is considered semi-ordered when: The first element is 1 The last element is n We are allowed to repeatedly swap adjacent elements. Each adjacent swap counts...

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LeetCode 2132 - Stamping the Grid

LeetCode Problem 2132 Difficulty: 🔴 Hard Topics: Array, Greedy, Matrix, Prefix Sum Solution Problem Understanding In this problem, we are given a binary matrix called grid . Every cell contains either: 0 , meaning the cell is empty 1 , meaning the cell is blocked or occupied We are also given a rectangular stamp with dimensions: stampHeight stampWidth The goal is to determine whether it is possible to place any...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3395 - Subsequences with a Unique Middle Mode I

LeetCode Problem 3395 Difficulty: 🔴 Hard Topics: Array, Hash Table, Math, Combinatorics Solution LeetCode 3395 - Subsequences with a Unique Middle Mode I Problem Understanding We are given an integer array nums , and we must count how many subsequences of length 5 satisfy a very specific condition: The subsequence must have exactly 5 elements. The middle element of the subsequence, meaning the third element seq[2] , must be the...

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LeetCode 3396 - Minimum Number of Operations to Make Elements in Array Distinct

LeetCode Problem 3396 Difficulty: 🟢 Easy Topics: Array, Hash Table Solution Problem Understanding The problem gives us an integer array nums , and our goal is to make all remaining elements distinct. The only allowed operation is removing exactly 3 elements from the beginning of the array. If fewer than 3 elements remain, we remove everything that is left. We need to determine the minimum number of such operations required...

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LeetCode 1944 - Number of Visible People in a Queue

LeetCode Problem 1944 Difficulty: 🔴 Hard Topics: Array, Stack, Monotonic Stack Solution Problem Understanding The problem gives a queue of n people standing from left to right, where each person has a distinct height. For each person i , we need to determine how many people to their right they can see. A person i can see a person j (with j > i ) if every person between them...

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LeetCode 3257 - Maximum Value Sum by Placing Three Rooks II

LeetCode Problem 3257 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Matrix, Enumeration Solution Problem Understanding We are given an m x n matrix called board , where each cell contains an integer value. We must place exactly three rooks on the board. A rook attacks every cell in the same row and the same column. Therefore, for three rooks to be valid, no two rooks can share either a row...

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LeetCode 2562 - Find the Array Concatenation Value

LeetCode Problem 2562 Difficulty: 🟢 Easy Topics: Array, Two Pointers, Simulation Solution Problem Understanding The problem is asking us to compute a special sum over a given array nums by repeatedly concatenating the first and last elements of the array until it is empty. The concatenation operation is not addition; it involves treating numbers as strings, joining them together, and then converting them back to integers. For example, concatenating 15...

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LeetCode 3314 - Construct the Minimum Bitwise Array I

LeetCode Problem 3314 Difficulty: 🟢 Easy Topics: Array, Bit Manipulation Solution Problem Understanding The problem asks us to construct an array ans from a given array nums of prime integers. For each element nums[i] , we need to find the smallest integer ans[i] such that the bitwise OR of ans[i] and ans[i] + 1 equals nums[i] . Formally, ans[i] | (ans[i] + 1) == nums[i] . If no such ans[i]...

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LeetCode 2252 - Dynamic Pivoting of a Table

LeetCode Problem 2252 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding This problem requires implementing a SQL-style pivot operation programmatically. The input is a table named Products with columns product_id , store , and price , where each row represents the price of a product in a specific store. The table has a compound primary key (product_id, store) and at most 30 unique stores. The goal is to reorganize the...

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LeetCode 2965 - Find Missing and Repeated Values

LeetCode Problem 2965 Difficulty: 🟢 Easy Topics: Array, Hash Table, Math, Matrix Solution LeetCode 2965 - Find Missing and Repeated Values Problem Understanding The problem gives us an n x n matrix called grid . Every value in the matrix should normally contain all integers from 1 to n² exactly once. However, there is one mistake in the matrix: One number appears twice. One number is completely missing. Our task...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2326 - Spiral Matrix IV

LeetCode Problem 2326 Difficulty: 🟡 Medium Topics: Array, Linked List, Matrix, Simulation Solution Problem Understanding The problem gives us a linked list and asks us to place its values into an m x n matrix in clockwise spiral order. We begin filling from the top-left corner of the matrix, which is position (0, 0) . The traversal direction follows the standard spiral pattern: Move left to right across the top...

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LeetCode 2485 - Find the Pivot Integer

LeetCode Problem 2485 Difficulty: 🟢 Easy Topics: Math, Prefix Sum Solution LeetCode 2485 - Find the Pivot Integer Problem Understanding The problem gives us a positive integer n and asks us to find a special integer x , called the pivot integer, such that: The sum of all integers from 1 to x is equal to The sum of all integers from x to n The important detail is that...

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LeetCode 2440 - Create Components With Same Value

LeetCode Problem 2440 Difficulty: 🔴 Hard Topics: Array, Math, Tree, Depth-First Search, Enumeration Solution Problem Understanding This problem is asking us to take an undirected tree where each node has a numerical value and determine how many edges we can remove such that every resulting connected component has the same total value. The tree is represented by a list of node values nums and a list of edges edges that...

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LeetCode 2277 - Closest Node to Path in Tree

LeetCode Problem 2277 Difficulty: 🔴 Hard Topics: Array, Tree, Depth-First Search, Breadth-First Search Solution Problem Understanding The problem is asking us to process queries on a tree structure. Each query gives a path between two nodes starti and endi and a third node nodei . We are asked to find which node along the path is closest to nodei in terms of the number of edges separating them, also known...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2508 - Add Edges to Make Degrees of All Nodes Even

LeetCode Problem 2508 Difficulty: 🔴 Hard Topics: Hash Table, Graph Theory Solution Problem Understanding The problem gives us an undirected graph with n nodes and a list of edges. Each edge connects two different nodes, and the graph may contain multiple disconnected components. Our task is to determine whether it is possible to add at most two new edges so that every node in the graph ends up having an...

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LeetCode 3309 - Maximum Possible Number by Binary Concatenation

LeetCode Problem 3309 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation, Enumeration Solution Problem Understanding The problem is asking for the maximum integer value that can be created by concatenating the binary representations of all elements in a list of three integers. Each number should be converted to its binary representation without leading zeros. After conversion, the binary strings can be concatenated in any order. The resulting binary string should then...

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LeetCode 3061 - Calculate Trapping Rain Water

LeetCode Problem 3061 Difficulty: 🔴 Hard Topics: Database Solution LeetCode 3061 - Calculate Trapping Rain Water Problem Understanding This problem asks us to compute how much rainwater can be trapped between vertical bars after rainfall. The bars are represented in a database table named Heights , where each row contains an id and a height . The id values are sequential, which means they define the left-to-right order of the...

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LeetCode 2337 - Move Pieces to Obtain a String

LeetCode Problem 2337 Difficulty: 🟡 Medium Topics: Two Pointers, String Solution Problem Understanding The problem gives us two strings, start and target , both having the same length. Each position in the strings contains one of three characters: 'L' , representing a piece that can only move left 'R' , representing a piece that can only move right '_' , representing an empty space A move consists of sliding a...

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LeetCode 2901 - Longest Unequal Adjacent Groups Subsequence II

LeetCode Problem 2901 Difficulty: 🟡 Medium Topics: Array, String, Dynamic Programming Solution Problem Understanding The problem asks us to select the longest subsequence of words from a given array such that adjacent words in the subsequence satisfy two conditions: first, their corresponding groups values are different , and second, the words are of the same length and differ by exactly one character (hamming distance = 1). In other words, we...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1914 - Cyclically Rotating a Grid

LeetCode Problem 1914 Difficulty: 🟡 Medium Topics: Array, Matrix, Simulation Solution LeetCode 1914 - Cyclically Rotating a Grid Problem Understanding The problem gives us an m x n matrix called grid , along with an integer k . Both dimensions of the matrix are guaranteed to be even numbers. The task is to rotate every layer of the matrix counter-clockwise exactly k times. A layer is the rectangular ring formed...

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LeetCode 2588 - Count the Number of Beautiful Subarrays

LeetCode Problem 2588 Difficulty: 🟡 Medium Topics: Array, Hash Table, Bit Manipulation, Prefix Sum Solution Problem Understanding The problem gives us an array nums , and we are allowed to repeatedly perform a special operation on pairs of elements. In one operation, we choose two different indices i and j , and also choose a bit position k such that both nums[i] and nums[j] currently have the k th bit...

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LeetCode 2463 - Minimum Total Distance Traveled

LeetCode Problem 2463 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Sorting Solution Here is a comprehensive, reference-quality solution guide for LeetCode 2463 - Minimum Total Distance Traveled following your formatting requirements. Problem Understanding The problem gives us a set of robots on an X-axis, each at a unique position, and a set of factories, each at a unique position with a maximum capacity of robots it can repair. Robots are...

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LeetCode 3243 - Shortest Distance After Road Addition Queries I

LeetCode Problem 3243 Difficulty: 🟡 Medium Topics: Array, Breadth-First Search, Graph Theory Solution Problem Understanding We are given n cities labeled from 0 to n - 1 . Initially, the graph forms a simple directed chain: 0 -> 1 1 -> 2 2 -> 3 ... n - 2 -> n - 1 This means that before processing any queries, the shortest path from city 0 to city n -...

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LeetCode 1905 - Count Sub Islands

LeetCode Problem 1905 Difficulty: 🟡 Medium Topics: Array, Depth-First Search, Breadth-First Search, Union-Find, Matrix Solution Problem Understanding The problem presents two m x n binary matrices, grid1 and grid2 , representing maps of land ( 1 ) and water ( 0 ). Each matrix may contain multiple islands, where an island is defined as a connected group of 1 s that are adjacent vertically or horizontally . The task is...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2785 - Sort Vowels in a String

LeetCode Problem 2785 Difficulty: 🟡 Medium Topics: String, Sorting Solution Problem Understanding This problem requires us to reorder the vowels in a string while keeping all consonants in their original positions. In simpler terms, we are asked to extract all vowels from a string, sort them by their ASCII values, and then put them back in their original positions, leaving consonants untouched. The input s is a string containing only...

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LeetCode 1935 - Maximum Number of Words You Can Type

LeetCode Problem 1935 Difficulty: 🟢 Easy Topics: Hash Table, String Solution Problem Understanding The problem is asking us to determine how many words in a given string can be fully typed on a malfunctioning keyboard. The keyboard has some broken letter keys that cannot be used. The input consists of a string text containing words separated by spaces, and a string brokenLetters containing the distinct letters that are broken. The...

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LeetCode 2957 - Remove Adjacent Almost-Equal Characters

LeetCode Problem 2957 Difficulty: 🟡 Medium Topics: String, Dynamic Programming, Greedy Solution LeetCode 2957 - Remove Adjacent Almost-Equal Characters Problem Understanding We are given a string word consisting of lowercase English letters. Two adjacent characters are considered almost-equal if either: They are exactly the same, such as 'a' and 'a' Their positions in the alphabet differ by exactly one, such as 'a' and 'b' , 'c' and 'b' , 'x'...

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LeetCode 1921 - Eliminate Maximum Number of Monsters

LeetCode Problem 1921 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting Solution Problem Understanding This problem asks us to determine how many monsters we can eliminate before any one of them reaches the city. Each monster starts at some distance from the city and moves toward it at a constant speed. We are also given a weapon that can eliminate exactly one monster every minute. The weapon starts fully charged at...

Practice › LeetCode › LeetCode 31xx ›

LeetCode 3178 - Find the Child Who Has the Ball After K Seconds

LeetCode Problem 3178 Difficulty: 🟢 Easy Topics: Math, Simulation Solution Problem Understanding The problem asks us to simulate a game in which n children, numbered from 0 to n - 1 , stand in a straight line. Child 0 starts with a ball, and every second the child holding the ball passes it to the next child in the current direction. The direction is initially to the right, and it...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2512 - Reward Top K Students

LeetCode Problem 2512 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Sorting, Heap (Priority Queue) Solution Problem Understanding The problem asks us to compute a ranking of students based on textual feedback they receive. We are given two lists of words: positive_feedback and negative_feedback . Every time a student receives a report, we score that report by adding 3 points for each word that appears in positive_feedback and subtracting 1...

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LeetCode 2457 - Minimum Addition to Make Integer Beautiful

LeetCode Problem 2457 Difficulty: 🟡 Medium Topics: Math, Greedy Solution Problem Understanding The problem asks us to transform a given integer n into a beautiful integer by adding the smallest non-negative integer x . An integer is defined as beautiful if the sum of its digits is less than or equal to a given target . The input consists of two numbers: n (the original number) and target (the maximum...

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LeetCode 2985 - Calculate Compressed Mean

LeetCode Problem 2985 Difficulty: 🟢 Easy Topics: Database Solution Problem Understanding This problem asks us to compute the average number of items per order from a compressed representation of order data. Instead of storing every individual order as a separate row, the table groups together orders that contain the same number of items. For each row: item_count represents how many items are in a particular type of order. order_occurrences represents...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2380 - Time Needed to Rearrange a Binary String

LeetCode Problem 2380 Difficulty: 🟡 Medium Topics: String, Dynamic Programming, Simulation Solution Problem Understanding This problem asks us to repeatedly transform a binary string according to a very specific rule. During each second, every occurrence of the substring "01" is replaced simultaneously with "10" . The important detail is that all replacements happen at the same time. This means we do not process one occurrence at a time from left...

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LeetCode 2164 - Sort Even and Odd Indices Independently

LeetCode Problem 2164 Difficulty: 🟢 Easy Topics: Array, Sorting Solution Problem Understanding The problem asks us to take an integer array nums and sort its elements based on their indices in two separate ways: the elements at even indices should be sorted in non-decreasing order, and the elements at odd indices should be sorted in non-increasing order. The array is 0-indexed , so index 0 is considered even, index 1...

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LeetCode 3230 - Customer Purchasing Behavior Analysis

LeetCode Problem 3230 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem asks us to analyze customer purchasing behavior using two relational tables: Transactions and Products . The Transactions table contains every purchase made by customers, including the transaction ID, customer ID, product ID, transaction date, and amount spent. The Products table contains the product catalog with product IDs, their categories, and prices. We are tasked with producing a...

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LeetCode 2452 - Words Within Two Edits of Dictionary

LeetCode Problem 2452 Difficulty: 🟡 Medium Topics: Array, String, Trie Solution Problem Understanding The problem asks us to identify words in the queries list that can be transformed into a word in the dictionary list with at most two character edits . Each edit consists of changing a single character to another lowercase English letter. The words in both arrays are guaranteed to have the same length, which simplifies comparison...

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LeetCode 2889 - Reshape Data: Pivot

LeetCode Problem 2889 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding This problem gives us a Pandas DataFrame named weather with three columns: city , the name of a city month , the name of a month temperature , the recorded temperature for that city during that month The task is to reshape the table using a pivot operation. Instead of storing each (city, month, temperature) combination as a separate...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2145 - Count the Hidden Sequences

LeetCode Problem 2145 Difficulty: 🟡 Medium Topics: Array, Prefix Sum Solution Problem Understanding The problem asks us to determine how many possible sequences of integers exist that match a given array of differences between consecutive elements, while staying within a specified inclusive range. Specifically, you are given an array differences of length n where each element represents the difference between consecutive elements of a hidden sequence of length n +...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1884 - Egg Drop With 2 Eggs and N Floors

LeetCode Problem 1884 Difficulty: 🟡 Medium Topics: Math, Dynamic Programming Solution LeetCode 1884 - Egg Drop With 2 Eggs and N Floors Problem Understanding This problem asks us to determine the minimum number of moves required to identify a critical floor f in a building with n floors, using exactly two eggs. The critical floor f has the following meaning: Any egg dropped from a floor higher than f will...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2915 - Length of the Longest Subsequence That Sums to Target

LeetCode Problem 2915 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution LeetCode 2915 - Length of the Longest Subsequence That Sums to Target Problem Understanding The problem gives us an array nums and an integer target . We must find a subsequence whose elements add up exactly to target , while maximizing the number of elements included in that subsequence. A subsequence is formed by deleting zero or more elements...

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LeetCode 2265 - Count Nodes Equal to Average of Subtree

LeetCode Problem 2265 Difficulty: 🟡 Medium Topics: Tree, Depth-First Search, Binary Tree Solution Problem Understanding This problem asks us to count how many nodes in a binary tree satisfy a specific condition: the node’s value must equal the average value of all nodes in its subtree . A subtree consists of the current node and every descendant below it. For each node, we need to compute: The total sum of...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3386 - Button with Longest Push Time

LeetCode Problem 3386 Difficulty: 🟢 Easy Topics: Array Solution Problem Understanding The problem gives us a sequence of keyboard button press events. Each event is represented as: [index, time] Here: index is the identifier of the button that was pressed. time is the moment when the press happened. The events are already sorted by increasing time, which is extremely important because it means we can process the presses in chronological...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2296 - Design a Text Editor

LeetCode Problem 2296 Difficulty: 🔴 Hard Topics: Linked List, String, Stack, Design, Simulation, Doubly-Linked List Solution Problem Understanding This problem asks us to design a simplified text editor that supports four operations: Inserting text at the current cursor position Deleting characters to the left of the cursor Moving the cursor left Moving the cursor right The cursor behaves exactly like a cursor in a normal text editor. It always sits...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1968 - Array With Elements Not Equal to Average of Neighbors

LeetCode Problem 1968 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting Solution Problem Understanding The problem asks us to rearrange a distinct integer array so that no element is equal to the average of its neighbors . The input is a zero-indexed array nums of length at least 3, and all elements are guaranteed to be distinct. The output should be any valid rearrangement of nums that satisfies the condition for...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2483 - Minimum Penalty for a Shop

LeetCode Problem 2483 Difficulty: 🟡 Medium Topics: String, Prefix Sum Solution Problem Understanding The problem asks us to determine the optimal hour to close a shop to minimize a penalty based on customer arrivals. The input is a string customers where each character represents an hour: 'Y' means customers arrive, and 'N' means no customers arrive. The shop can close at any hour from 0 to n (inclusive), and the...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2941 - Maximum GCD-Sum of a Subarray

LeetCode Problem 2941 Difficulty: 🔴 Hard Topics: Array, Math, Binary Search, Number Theory Solution Problem Understanding The problem asks us to find the maximum gcd-sum of a subarray of a given integer array nums with the constraint that the subarray has at least k elements. The gcd-sum of a subarray is defined as the product of the sum of its elements and the greatest common divisor (GCD) of its elements....

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LeetCode 2943 - Maximize Area of Square Hole in Grid

LeetCode Problem 2943 Difficulty: 🟡 Medium Topics: Array, Sorting Solution LeetCode 2943 - Maximize Area of Square Hole in Grid Problem Understanding The grid is formed by n + 2 horizontal bars and m + 2 vertical bars. These bars divide the plane into unit squares. The bars are numbered starting from 1 . Some horizontal bars listed in hBars may be removed, and some vertical bars listed in vBars...

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LeetCode 3269 - Constructing Two Increasing Arrays

LeetCode Problem 3269 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming Solution Problem Understanding We are given two binary arrays, nums1 and nums2 . Each element is either 0 or 1 . We must replace every value with a positive integer according to its parity: Every 0 must become an even positive integer. Every 1 must become an odd positive integer. After replacement, both resulting arrays must satisfy two conditions: Each...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2615 - Sum of Distances

LeetCode Problem 2615 Difficulty: 🟡 Medium Topics: Array, Hash Table, Prefix Sum Solution Problem Understanding The problem asks us to compute, for every index i in the array nums , the total distance between i and every other index j where nums[j] == nums[i] . More formally, for each position i , we need to calculate: $$\sum |i - j|$$ for all indices j such that: nums[j] == nums[i] j...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2270 - Number of Ways to Split Array

LeetCode Problem 2270 Difficulty: 🟡 Medium Topics: Array, Prefix Sum Solution Problem Understanding The problem asks us to determine the number of ways to split a given 0-indexed array nums into two non-empty contiguous subarrays such that the sum of the first part is greater than or equal to the sum of the second part. Formally, a split at index i is valid if sum(nums[0:i+1]) >= sum(nums[i+1:n]) and 0 <=...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1962 - Remove Stones to Minimize the Total

LeetCode Problem 1962 Difficulty: 🟡 Medium Topics: Array, Greedy, Heap (Priority Queue) Solution Problem Understanding The problem gives us an array called piles , where each element represents the number of stones in a pile. We are also given an integer k , representing the exact number of operations we must perform. In one operation, we choose a pile and remove floor(pile / 2) stones from it. Since we remove...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1991 - Find the Middle Index in Array

LeetCode Problem 1991 Difficulty: 🟢 Easy Topics: Array, Prefix Sum Solution LeetCode 1991 - Find the Middle Index in Array Problem Understanding The problem gives us a 0-indexed integer array called nums . We need to find an index such that the sum of all elements to the left of that index is equal to the sum of all elements to the right of that index. More formally, for an...

Practice › LeetCode › LeetCode 30xx ›

LeetCode 3051 - Find Candidates for Data Scientist Position

LeetCode Problem 3051 Difficulty: 🟢 Easy Topics: Database Solution You included two different LeetCode problems with conflicting templates. The second problem appears to be the one you want covered: LeetCode 3051 - Find Candidates for Data Scientist Position (Database) However, the required sections still reference Python and Go solutions, test cases with assert , and algorithm walkthroughs, which do not apply to a SQL database problem. For a Database problem,...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3267 - Count Almost Equal Pairs II

LeetCode Problem 3267 Difficulty: 🔴 Hard Topics: Array, Hash Table, Sorting, Counting, Enumeration Solution LeetCode 3267 - Count Almost Equal Pairs II Problem Understanding We are given an array nums containing positive integers. We need to count how many pairs of indices (i, j) with i < j satisfy a special condition called almost equal . Two numbers x and y are considered almost equal if we can make them...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2186 - Minimum Number of Steps to Make Two Strings Anagram II

LeetCode Problem 2186 Difficulty: 🟡 Medium Topics: Hash Table, String, Counting Solution Problem Understanding The problem asks us to find the minimum number of steps required to make two strings, s and t , anagrams of each other. An anagram means that both strings must contain the exact same characters with the same frequency, though their order can differ. In this problem, a "step" allows appending any character to either...

Practice › LeetCode › LeetCode 30xx ›

LeetCode 3039 - Apply Operations to Make String Empty

LeetCode Problem 3039 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sorting, Counting Solution LeetCode 3039 - Apply Operations to Make String Empty Problem Understanding The problem gives us a lowercase string s and defines a repeated operation. During one operation, we scan through all letters from 'a' to 'z' . For each letter, if that letter appears in the current string, we remove its first occurrence. This process continues until...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2526 - Find Consecutive Integers from a Data Stream

LeetCode Problem 2526 Difficulty: 🟡 Medium Topics: Hash Table, Design, Queue, Counting, Data Stream Solution Problem Understanding The problem asks us to design a data structure that continuously processes a stream of integers and determines whether the most recent k integers are all equal to a specific target value. We are given two parameters when initializing the data structure: value , which represents the integer we are interested in tracking....

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LeetCode 2590 - Design a Todo List

LeetCode Problem 2590 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Design, Sorting Solution Problem Understanding This problem asks us to design a small task management system, similar to a lightweight todo application. We need to implement a TodoList class that supports adding tasks, marking tasks as completed, retrieving all pending tasks for a user, and filtering pending tasks by tag. Each task belongs to a specific user and contains...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2282 - Number of People That Can Be Seen in a Grid

LeetCode Problem 2282 Difficulty: 🟡 Medium Topics: Array, Stack, Matrix, Monotonic Stack Solution Problem Understanding The problem asks us to determine, for each person in a 2D grid of heights, how many other people they can see according to a specific line-of-sight rule. Each person at position (i, j) can see another person either directly to the right in the same row or directly below in the same column. The...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2409 - Count Days Spent Together

LeetCode Problem 2409 Difficulty: 🟢 Easy Topics: Math, String Solution Problem Understanding The problem asks us to calculate the number of days Alice and Bob spend together in Rome based on their respective arrival and departure dates. Each date is represented as a string in the format "MM-DD" . The input consists of four strings: arriveAlice , leaveAlice , arriveBob , and leaveBob . The output should be the total...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2072 - The Winner University

LeetCode Problem 2072 Difficulty: 🟢 Easy Topics: Database Solution Problem Understanding The problem gives us two database tables, NewYork and California . Each table contains the exam scores of students from a university. Every row represents a single student, identified by a unique student_id , along with their score . The competition rule is straightforward. A student is considered an excellent student if their score is greater than or equal...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3357 - Minimize the Maximum Adjacent Element Difference

LeetCode Problem 3357 Difficulty: 🔴 Hard Topics: Array, Binary Search, Greedy Solution Problem Understanding The problem gives us an integer array nums , where some positions contain -1 . These -1 values represent missing elements that must be replaced. The key restriction is that we are allowed to choose exactly two positive integers, x and y , one time globally for the entire array. Every missing value must then be...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2416 - Sum of Prefix Scores of Strings

LeetCode Problem 2416 Difficulty: 🔴 Hard Topics: Array, String, Trie, Counting Solution Problem Understanding The problem is asking us to compute a special score for each string in a list of strings. Specifically, for a string term , its score is defined as the number of strings in the array that have term as a prefix. The main task is to compute, for each string in the list, the sum...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2516 - Take K of Each Character From Left and Right

LeetCode Problem 2516 Difficulty: 🟡 Medium Topics: Hash Table, String, Sliding Window Solution Problem Understanding The problem asks us to determine the minimum number of characters to take from either end of a string s consisting only of the letters 'a' , 'b' , and 'c' so that we collect at least k of each character . You are allowed to take characters from the leftmost or rightmost position of...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2255 - Count Prefixes of a Given String

LeetCode Problem 2255 Difficulty: 🟢 Easy Topics: Array, String Solution Problem Understanding The problem asks us to determine how many strings in a given array words are prefixes of a target string s . A prefix of a string is defined as any substring that starts at the first character and continues for any length up to the length of the string itself. For example, "ab" is a prefix of...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2240 - Number of Ways to Buy Pens and Pencils

LeetCode Problem 2240 Difficulty: 🟡 Medium Topics: Math, Enumeration Solution Problem Understanding The problem asks us to determine the number of distinct ways to spend a given amount of money, total , on pens and pencils, each with fixed costs, cost1 for pens and cost2 for pencils. You can buy any non-negative number of each item, including zero, as long as the total cost does not exceed your budget. The...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2041 - Accepted Candidates From the Interviews

LeetCode Problem 2041 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem gives us two database tables, Candidates and Rounds , that together describe interview performance for job candidates. The Candidates table contains one row per candidate. Each row includes the candidate's unique ID, name, years of experience, and the interview ID associated with that candidate. The Rounds table contains the scores for individual interview rounds. Each interview can...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2235 - Add Two Integers

LeetCode Problem 2235 Difficulty: 🟢 Easy Topics: Math Solution Problem Understanding The problem is asking for the sum of two integers num1 and num2 . In simpler terms, you are given two numbers, and you need to calculate their total. The input integers can be negative, zero, or positive, and the output should be a single integer representing the sum. The constraints specify that both num1 and num2 are within...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3308 - Find Top Performing Driver

LeetCode Problem 3308 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem asks us to identify the top-performing driver for each fuel type based on the trips data. We are given three tables: Drivers , Vehicles , and Trips . Each driver may operate one or more vehicles, and each vehicle may have multiple trips. The goal is to compute, for each fuel type, the driver with the highest...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2432 - The Employee That Worked on the Longest Task

LeetCode Problem 2432 Difficulty: 🟢 Easy Topics: Array Solution Problem Understanding The problem asks us to identify which employee worked the task with the longest duration given a sequence of tasks completed by employees. Each task is represented in logs[i] = [idi, leaveTimei] , where idi is the employee id and leaveTimei is the time the task was completed. The start time of each task is implicitly defined: the first...

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LeetCode 3006 - Find Beautiful Indices in the Given Array I

LeetCode Problem 3006 Difficulty: 🟡 Medium Topics: Two Pointers, String, Binary Search, Rolling Hash, String Matching, Hash Function Solution Problem Understanding The problem gives us a string s and two smaller strings, a and b . We need to find every index i where substring a appears in s , but only if there exists at least one occurrence of substring b close enough to it. More formally, an index...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3272 - Find the Count of Good Integers

LeetCode Problem 3272 Difficulty: 🔴 Hard Topics: Hash Table, Math, Combinatorics, Enumeration Solution Problem Understanding The problem asks us to count n-digit integers that are "good" with respect to a given integer k . A "good" integer is one whose digits can be rearranged to form a k-palindromic integer . A k-palindromic integer is defined as an integer that satisfies two properties: it is a palindrome (reads the same forwards...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2934 - Minimum Operations to Maximize Last Elements in Arrays

LeetCode Problem 2934 Difficulty: 🟡 Medium Topics: Array, Enumeration Solution LeetCode 2934 - Minimum Operations to Maximize Last Elements in Arrays Problem Understanding You are given two arrays, nums1 and nums2 , both of the same length n . For every index i , you may optionally swap the pair (nums1[i], nums2[i]) . Each swap counts as one operation. Your goal is to make the last element of each array...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2096 - Step-By-Step Directions From a Binary Tree Node to Another

LeetCode Problem 2096 Difficulty: 🟡 Medium Topics: String, Tree, Depth-First Search, Binary Tree Solution Problem Understanding The problem gives us a binary tree where every node contains a unique value from 1 to n . We are also given two node values: startValue , the node where the path begins destValue , the node where the path must end We must return the shortest sequence of directions needed to move...

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LeetCode 3005 - Count Elements With Maximum Frequency

LeetCode Problem 3005 Difficulty: 🟢 Easy Topics: Array, Hash Table, Counting Solution LeetCode 3005 - Count Elements With Maximum Frequency Problem Understanding The problem gives us an integer array nums , where every value is positive. We need to determine which elements appear most frequently, then return the total number of occurrences contributed by all such elements. In other words, we first compute the frequency of every distinct number in...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2842 - Count K-Subsequences of a String With Maximum Beauty

LeetCode Problem 2842 Difficulty: 🔴 Hard Topics: Hash Table, Math, String, Greedy, Sorting, Combinatorics Solution Problem Understanding The problem requires us to count k-subsequences of a string s that have the maximum beauty , where beauty is defined as the sum of the frequency of each character in the subsequence. A k-subsequence is a subsequence of length k where all characters are unique. The input string can be up to...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2746 - Decremental String Concatenation

LeetCode Problem 2746 Difficulty: 🟡 Medium Topics: Array, String, Dynamic Programming Solution LeetCode 2746 - Decremental String Concatenation Problem Understanding The problem gives us an array of strings words . We start with words[0] and then process the remaining strings one by one. For each new word words[i] , we have exactly two choices: Append it to the right side of the current string. Append it to the left side...

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LeetCode 2743 - Count Substrings Without Repeating Character

LeetCode Problem 2743 Difficulty: 🟡 Medium Topics: Hash Table, String, Sliding Window Solution Problem Understanding The problem asks us to count how many substrings of a given string contain only unique characters. A substring is considered special if no character appears more than once inside that substring. We are given a string s containing only lowercase English letters. For every possible contiguous substring, we need to determine whether all characters...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2389 - Longest Subsequence With Limited Sum

LeetCode Problem 2389 Difficulty: 🟢 Easy Topics: Array, Binary Search, Greedy, Sorting, Prefix Sum Solution Problem Understanding This problem asks us to determine, for each query, the maximum number of elements we can select from an array nums such that their sum does not exceed a given value. We are not required to maintain consecutive elements, only the relative order for subsequences, but in this problem the relative order does...

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LeetCode 2089 - Find Target Indices After Sorting Array

LeetCode Problem 2089 Difficulty: 🟢 Easy Topics: Array, Binary Search, Sorting Solution LeetCode 2089, Find Target Indices After Sorting Array Problem Understanding The problem gives us an integer array nums and an integer target . We must sort the array in non-decreasing order and then return every index where the value equals target . A target index is simply an index i such that: $nums[i] = target$ The important detail...

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LeetCode 3160 - Find the Number of Distinct Colors Among the Balls

LeetCode Problem 3160 Difficulty: 🟡 Medium Topics: Array, Hash Table, Simulation Solution Problem Understanding The problem gives us limit + 1 balls labeled from 0 to limit . Initially, none of the balls have a color assigned. We then process a sequence of queries, where each query is of the form [x, y] . This means ball x should now be painted with color y . The important detail is...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2228 - Users With Two Purchases Within Seven Days

LeetCode Problem 2228 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem requires identifying users who made at least two purchases within a 7-day window. We are given a Purchases table with purchase_id , user_id , and purchase_date . Each row represents a single purchase made by a user. The goal is to return the IDs of users who had two or more purchases where the difference between any...

Practice › LeetCode › LeetCode 30xx ›

LeetCode 3032 - Count Numbers With Unique Digits II

LeetCode Problem 3032 Difficulty: 🟢 Easy Topics: Hash Table, Math, Dynamic Programming Solution Problem Understanding The problem asks us to count how many integers in the inclusive range [a, b] contain only unique digits . A number has unique digits if no digit appears more than once within that number. For example, the number 123 has unique digits because 1 , 2 , and 3 each appear exactly once. However,...

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LeetCode 3038 - Maximum Number of Operations With the Same Score I

LeetCode Problem 3038 Difficulty: 🟢 Easy Topics: Array, Simulation Solution Problem Understanding The problem asks us to repeatedly perform an operation on an integer array nums . In each operation, we remove the first two elements of the array and compute a score , which is simply the sum of those two removed values. The key restriction is that every operation must have the exact same score . We are...

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LeetCode 2960 - Count Tested Devices After Test Operations

LeetCode Problem 2960 Difficulty: 🟢 Easy Topics: Array, Simulation, Counting Solution Problem Understanding This problem asks us to simulate a sequence of device tests based on battery percentages. We are given a 0-indexed integer array batteryPercentages , where each element represents the current battery level of a device. We process the devices from left to right, starting at index 0 and ending at index n - 1 . For each...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2342 - Max Sum of a Pair With Equal Sum of Digits

LeetCode Problem 2342 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sorting, Heap (Priority Queue) Solution Problem Understanding The problem requires finding the maximum sum of a pair of numbers in an array such that the sum of the digits of both numbers is equal. Specifically, you are given a 0-indexed array nums containing positive integers. You can choose two distinct indices i and j such that i != j ,...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1874 - Minimize Product Sum of Two Arrays

LeetCode Problem 1874 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting Solution Problem Understanding The problem defines the product sum of two arrays as the sum of the products of corresponding elements at the same indices. If we have arrays a and b , then the product sum is: $$\sum_{i=0}^{n-1} a[i] \times b[i]$$ We are given two arrays, nums1 and nums2 , both of the same length n . We are...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2538 - Difference Between Maximum and Minimum Price Sum

LeetCode Problem 2538 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Tree, Depth-First Search Solution Problem Understanding We are given an undirected tree with n nodes. Every node has a price value. Since the graph is a tree, there is exactly one simple path between any two nodes. The problem allows us to choose any node as the root of the tree. After choosing a root, we consider all paths that...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2621 - Sleep

LeetCode Problem 2621 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding The problem asks us to implement an asynchronous function sleep that pauses execution for a given number of milliseconds, specified by the input millis . In other words, when sleep(millis) is called, the function should return a promise that resolves after approximately millis milliseconds have passed. The resolved value can be any value, as the problem does not enforce...

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LeetCode 2871 - Split Array Into Maximum Number of Subarrays

LeetCode Problem 2871 Difficulty: 🟡 Medium Topics: Array, Greedy, Bit Manipulation Solution Problem Understanding The problem is asking us to split a given array of non-negative integers into contiguous subarrays in a way that maximizes the number of subarrays , while minimizing the sum of their bitwise AND scores . The score of a subarray is defined as the bitwise AND of all elements in that subarray. Since AND-ing any...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2347 - Best Poker Hand

LeetCode Problem 2347 Difficulty: 🟢 Easy Topics: Array, Hash Table, Counting Solution Problem Understanding The problem gives us exactly five playing cards. Each card is represented by two pieces of information: ranks[i] represents the numerical rank of the card, from 1 to 13 suits[i] represents the suit of the card, using characters from 'a' to 'd' We need to determine the strongest poker hand that can be formed from these...

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LeetCode 2361 - Minimum Costs Using the Train Line

LeetCode Problem 2361 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming Solution Problem Understanding This problem models a scenario where you are traversing a train line with two parallel routes: a regular route and an express route. Each route has a series of consecutive stops, and the cost to move from one stop to the next is provided in the arrays regular and express . You always start at stop 0...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2929 - Distribute Candies Among Children II

LeetCode Problem 2929 Difficulty: 🟡 Medium Topics: Math, Combinatorics, Enumeration Solution Problem Understanding The problem asks us to calculate the total number of ways to distribute n candies among exactly three children, with the constraint that no child can receive more than limit candies. Essentially, we are asked to enumerate all possible triplets (a, b, c) of non-negative integers that satisfy two conditions: a + b + c = n...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2791 - Count Paths That Can Form a Palindrome in a Tree

LeetCode Problem 2791 Difficulty: 🔴 Hard Topics: Hash Table, Bit Manipulation, Tree, Depth-First Search Solution I can do that, but the guide will be very long for a single chat response because your required format includes detailed prose, brute force and optimal approaches, proof sketch, Python and Go implementations, worked traces for every example, complexity analysis, comprehensive tests, and edge cases for a Hard problem. To avoid truncation and keep...

Practice › LeetCode › LeetCode 31xx ›

LeetCode 3166 - Calculate Parking Fees and Duration

LeetCode Problem 3166 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem asks us to analyze parking transaction records and compute aggregated statistics for each car. Every row in the ParkingTransactions table represents one parking session, containing the parking lot ID, the car ID, the entry and exit timestamps, and the fee paid for that session. For every distinct car_id , we must compute three values: The total parking...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2678 - Number of Senior Citizens

LeetCode Problem 2678 Difficulty: 🟢 Easy Topics: Array, String Solution Problem Understanding This problem asks us to count the number of passengers in a list who are strictly older than 60. Each passenger's information is compressed into a fixed-length string of 15 characters. The string is structured as follows: the first ten characters represent the phone number, the eleventh character represents gender, the twelfth and thirteenth characters represent the age,...

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LeetCode 2056 - Number of Valid Move Combinations On Chessboard

LeetCode Problem 2056 Difficulty: 🔴 Hard Topics: Array, String, Backtracking, Simulation Solution Problem Understanding The problem asks us to calculate the total number of valid move combinations for a small set of chess pieces (up to four) on an 8 x 8 chessboard. Each piece-rook, bishop, or queen-can move according to standard chess rules, but only along paths defined by the piece's movement. A move combination consists of assigning a...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2341 - Maximum Number of Pairs in Array

LeetCode Problem 2341 Difficulty: 🟢 Easy Topics: Array, Hash Table, Counting Solution Problem Understanding The problem asks us to take an array of integers, nums , and repeatedly form pairs of equal numbers until no more pairs can be formed. Each operation removes exactly two identical numbers from the array, and we continue doing this until it is no longer possible. The goal is to return a list of two...

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LeetCode 2893 - Calculate Orders Within Each Interval

LeetCode Problem 2893 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem asks us to process an Orders table where each row contains a minute and the number of orders received during that specific minute. We are tasked with calculating the total number of orders in intervals of six consecutive minutes. For example, minutes 1 through 6 are interval 1, minutes 7 through 12 are interval 2, and so...

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LeetCode 3262 - Find Overlapping Shifts

LeetCode Problem 3262 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem requires counting overlapping shifts for each employee from a database table called EmployeeShifts . Each row in this table represents a single shift worked by an employee, with a start_time and an end_time . Two shifts are considered overlapping if one shift ends after another shift starts, meaning that their time intervals intersect. The goal is to...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2680 - Maximum OR

LeetCode Problem 2680 Difficulty: 🟡 Medium Topics: Array, Greedy, Bit Manipulation, Prefix Sum Solution Problem Understanding In this problem, we are given an integer array nums and an integer k . We may perform at most k operations, where each operation selects one element and multiplies it by 2 . Multiplying by 2 in binary is equivalent to shifting all bits one position to the left. For example: 5 in...

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LeetCode 3146 - Permutation Difference between Two Strings

LeetCode Problem 3146 Difficulty: 🟢 Easy Topics: Hash Table, String Solution Problem Understanding The problem asks us to compute the permutation difference between two strings, s and t . Both strings contain unique characters, and t is a permutation of s . The permutation difference is calculated by taking each character in s , finding its index in both s and t , and summing the absolute differences of these...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2238 - Number of Times a Driver Was a Passenger

LeetCode Problem 2238 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem provides a table Rides that records rides between drivers and passengers. Each row has a unique ride_id , a driver_id , and a passenger_id . The task is to determine, for each driver, how many times that driver has appeared as a passenger in the table. In other words, for each unique driver_id , we count the...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2156 - Find Substring With Given Hash Value

LeetCode Problem 2156 Difficulty: 🔴 Hard Topics: String, Sliding Window, Rolling Hash, Hash Function Solution Problem Understanding This problem asks us to find the earliest substring of length k whose polynomial rolling hash equals a given target value. The hash function is defined as: $$hash(s, p, m) = \left( \sum_{i=0}^{k-1} val(s[i]) \cdot p^i \right) \bmod m$$ where: val('a') = 1 val('b') = 2 ... val('z') = 26 For a substring...

Practice › LeetCode › LeetCode 30xx ›

LeetCode 3050 - Pizza Toppings Cost Analysis

LeetCode Problem 3050 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem asks us to compute the total cost of all possible three-topping pizza combinations using a list of available toppings from a database table. Each topping has a name and a cost, and toppings are unique. The key requirements are that no topping can be repeated in a combination, toppings must be listed in alphabetical order in the...

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LeetCode 3093 - Longest Common Suffix Queries

LeetCode Problem 3093 Difficulty: 🔴 Hard Topics: Array, String, Trie Solution Problem Understanding The problem asks us to process a set of suffix matching queries efficiently. We are given two arrays: wordsContainer , which contains candidate strings wordsQuery , which contains query strings For every query string, we must find the index of the string in wordsContainer that shares the longest common suffix with that query. A suffix is the...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2406 - Divide Intervals Into Minimum Number of Groups

LeetCode Problem 2406 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Greedy, Sorting, Heap (Priority Queue), Prefix Sum Solution Problem Understanding The problem gives us a list of inclusive intervals, where each interval is represented as [left, right] . We must divide all intervals into groups such that no two intervals inside the same group intersect. The important detail is that the intervals are inclusive. This means two intervals overlap even...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3256 - Maximum Value Sum by Placing Three Rooks I

LeetCode Problem 3256 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Matrix, Enumeration Solution Problem Understanding We are given an m x n matrix called board , where each cell contains an integer value. We must place exactly three rooks on the board. A rook attacks every square in the same row and the same column. Therefore, for three rooks to be valid: No two rooks can share the same row...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2766 - Relocate Marbles

LeetCode Problem 2766 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sorting, Simulation Solution Problem Understanding The problem gives us an array nums representing the positions of marbles on a number line. Multiple marbles may exist at the same position, so nums can contain duplicates. We are also given two arrays, moveFrom and moveTo , which describe a sequence of move operations. For each index i , we must move every...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2601 - Prime Subtraction Operation

LeetCode Problem 2601 Difficulty: 🟡 Medium Topics: Array, Math, Binary Search, Greedy, Number Theory Solution Problem Understanding The problem gives us an integer array nums and asks whether it is possible to transform the array into a strictly increasing sequence by performing a special operation. For any index i , we may choose that index at most once and subtract a prime number p from nums[i] , where p must...

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LeetCode 2660 - Determine the Winner of a Bowling Game

LeetCode Problem 2660 Difficulty: 🟢 Easy Topics: Array, Simulation Solution Problem Understanding The problem describes a simplified scoring system for a bowling game between two players. Each player has an array representing the number of pins hit in each turn, and there are exactly n turns. Each turn normally scores the number of pins hit, but a bonus rule applies: if the player scored a strike (10 pins) in either...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1993 - Operations on Tree

LeetCode Problem 1993 Difficulty: 🟡 Medium Topics: Array, Hash Table, Tree, Depth-First Search, Breadth-First Search, Design Solution LeetCode 1993 - Operations on Tree Problem Understanding The problem asks us to design a mutable tree-based data structure that supports three operations: lock , unlock , and upgrade . Each node in the tree may either be unlocked or locked by exactly one user. The operations must follow strict rules about when...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3255 - Find the Power of K-Size Subarrays II

LeetCode Problem 3255 Difficulty: 🟡 Medium Topics: Array, Sliding Window Solution Problem Understanding The problem asks us to evaluate every contiguous subarray of length k in the given array nums . For each subarray, we must determine whether it satisfies two conditions simultaneously: The elements are sorted in strictly ascending order. Every adjacent pair differs by exactly 1 , meaning the values are consecutive integers. If both conditions are true,...

Practice › LeetCode › LeetCode 31xx ›

LeetCode 3144 - Minimum Substring Partition of Equal Character Frequency

LeetCode Problem 3144 Difficulty: 🟡 Medium Topics: Hash Table, String, Dynamic Programming, Counting Solution Problem Understanding In this problem, we are given a lowercase English string s , and we must split it into one or more contiguous substrings such that every substring is balanced . A substring is considered balanced when every distinct character inside it appears the same number of times. The actual frequency does not matter, only...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2586 - Count the Number of Vowel Strings in Range

LeetCode Problem 2586 Difficulty: 🟢 Easy Topics: Array, String, Counting Solution Problem Understanding The problem gives us an array of lowercase strings called words and two integer indices, left and right . We need to count how many strings within the inclusive range [left, right] are considered vowel strings. A string qualifies as a vowel string if both of these conditions are true: The first character is a vowel. The...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1832 - Check if the Sentence Is Pangram

LeetCode Problem 1832 Difficulty: 🟢 Easy Topics: Hash Table, String Solution Problem Understanding This problem asks us to determine whether a given string is a pangram. A pangram is a sentence that contains every lowercase English letter, from 'a' through 'z' , at least once. The input is a single string named sentence . The problem guarantees that the string contains only lowercase English letters, which simplifies the implementation because...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2276 - Count Integers in Intervals

LeetCode Problem 2276 Difficulty: 🔴 Hard Topics: Design, Segment Tree, Ordered Set Solution Problem Understanding This problem asks us to design a data structure that dynamically maintains a collection of integer intervals and efficiently reports how many distinct integers are covered by at least one interval. Initially, the interval set is empty. We must support two operations: add(left, right) , which inserts a new interval [left, right] count() , which...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2830 - Maximize the Profit as the Salesman

LeetCode Problem 2830 Difficulty: 🟡 Medium Topics: Array, Hash Table, Binary Search, Dynamic Programming, Sorting Solution LeetCode 2830 - Maximize the Profit as the Salesman Problem Understanding This problem gives us n houses arranged on a number line and a collection of purchase offers. Each offer is represented as [start, end, gold] , meaning a buyer wants to purchase every house in the inclusive range [start, end] and is willing...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2758 - Next Day

LeetCode Problem 2758 Difficulty: 🟢 Easy Topics: — Solution LeetCode 2758 - Next Day Problem Understanding This problem asks us to extend JavaScript's built in Date object by adding a new method called nextDay() . Once implemented, any valid Date instance should be able to call this method and receive a string representing the next calendar day in the format YYYY-MM-DD . The input is a valid JavaScript Date object....

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2336 - Smallest Number in Infinite Set

LeetCode Problem 2336 Difficulty: 🟡 Medium Topics: Hash Table, Design, Heap (Priority Queue), Ordered Set Solution Problem Understanding The problem asks us to implement a data structure representing an infinite set of positive integers, initially containing all integers starting from 1. We need to provide two main operations: popSmallest , which removes and returns the smallest integer in the set, and addBack , which adds a previously removed integer back...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3356 - Zero Array Transformation II

LeetCode Problem 3356 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Binary Search, Prefix Sum Solution Problem Understanding The problem asks us to determine the minimum number of sequential queries required to transform an array nums into a Zero Array , where all elements are zero. Each query specifies a subarray [li, ri] and a value vali . We are allowed to decrement each element within that subarray by any value...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3389 - Minimum Operations to Make Character Frequencies Equal

LeetCode Problem 3389 Difficulty: 🔴 Hard Topics: Hash Table, String, Dynamic Programming, Counting, Enumeration Solution Problem Understanding The problem requires transforming a given string s into a good string , where a good string is defined as one in which every character appears the same number of times. The operations allowed include deleting a character, inserting a character, or incrementing a character to the next letter in the alphabet (with...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2744 - Find Maximum Number of String Pairs

LeetCode Problem 2744 Difficulty: 🟢 Easy Topics: Array, Hash Table, String, Simulation Solution LeetCode 2744 - Find Maximum Number of String Pairs Problem Understanding This problem gives us an array words containing distinct strings. Every string has length exactly 2 , and all strings consist of lowercase English letters. We can form a pair between two strings words[i] and words[j] when: i < j One string is exactly the reverse...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2413 - Smallest Even Multiple

LeetCode Problem 2413 Difficulty: 🟢 Easy Topics: Math, Number Theory Solution Problem Understanding The problem asks us to find the smallest positive integer that is a multiple of both 2 and a given positive integer n . In other words, we are looking for the least common multiple (LCM) of 2 and n . The input n is guaranteed to be between 1 and 150 , which is a very...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2793 - Status of Flight Tickets

LeetCode Problem 2793 Difficulty: 🔴 Hard Topics: — Solution Problem Understanding This problem asks us to determine whether each passenger's ticket is confirmed or placed on the waitlist , based on the booking order and the capacity of the flight they booked. We are given two database tables: The Flights table contains information about each flight and its seating capacity. Each row specifies a unique flight_id and the maximum number...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3325 - Count Substrings With K-Frequency Characters I

LeetCode Problem 3325 Difficulty: 🟡 Medium Topics: Hash Table, String, Sliding Window Solution Problem Understanding The problem asks us to count all substrings of a given string s such that at least one character in the substring appears at least k times . In simpler terms, for every substring we consider, we check whether there is any character that has frequency greater than or equal to k . If there...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2054 - Two Best Non-Overlapping Events

LeetCode Problem 2054 Difficulty: 🟡 Medium Topics: Array, Binary Search, Dynamic Programming, Sorting, Heap (Priority Queue) Solution Problem Understanding The problem gives us a list of events, where each event is represented as: [startTime, endTime, value] Each event occupies an inclusive time interval from startTime to endTime . If we attend that event, we earn value points. We are allowed to attend at most two events, but the chosen events...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2465 - Number of Distinct Averages

LeetCode Problem 2465 Difficulty: 🟢 Easy Topics: Array, Hash Table, Two Pointers, Sorting Solution Problem Understanding The problem requires calculating the number of distinct averages generated from a sequence of numbers using a specific process. The input is an integer array nums of even length. The process repeatedly removes the smallest and largest numbers from the array, calculates their average, and continues until the array is empty. The output is...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2650 - Design Cancellable Function

LeetCode Problem 2650 Difficulty: 🔴 Hard Topics: — Solution Problem Understanding The problem asks us to implement a mechanism to run a generator that yields promises, with the additional ability to cancel the execution at any time. The key task is to manage the generator’s asynchronous execution in a way that each yielded promise is awaited and its result sent back into the generator. If any promise rejects, the error...

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LeetCode 2458 - Height of Binary Tree After Subtree Removal Queries

LeetCode Problem 2458 Difficulty: 🔴 Hard Topics: Array, Tree, Depth-First Search, Breadth-First Search, Binary Tree Solution Problem Understanding This problem asks us to answer multiple independent queries on a binary tree. For each query, we temporarily remove an entire subtree rooted at a specific node, then compute the height of the remaining tree. The binary tree contains n nodes, and every node has a unique value from 1 to n...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2525 - Categorize Box According to Criteria

LeetCode Problem 2525 Difficulty: 🟢 Easy Topics: Math Solution Problem Understanding The problem requires categorizing a box based on its dimensions and mass according to given criteria. We are given four integers: length , width , height , and mass . The output is a string that represents the category of the box: "Bulky" , "Heavy" , "Both" , or "Neither" . A box is "Bulky" if any dimension is...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2913 - Subarrays Distinct Element Sum of Squares I

LeetCode Problem 2913 Difficulty: 🟢 Easy Topics: Array, Hash Table Solution Problem Understanding The problem asks us to examine every possible non-empty subarray of the given array nums . For each subarray, we compute how many distinct values appear inside it. After finding this distinct count, we square it and add it to the final answer. A subarray is contiguous, which means the elements must appear next to each other...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2184 - Number of Ways to Build Sturdy Brick Wall

LeetCode Problem 2184 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to compute the number of ways to build a wall of given height and width using bricks of specified widths, such that the wall is sturdy . A wall is sturdy if no two adjacent rows have bricks that meet at the same position horizontally, except at the ends of...

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LeetCode 2946 - Matrix Similarity After Cyclic Shifts

LeetCode Problem 2946 Difficulty: 🟢 Easy Topics: Array, Math, Matrix, Simulation Solution Problem Understanding This problem asks us to determine whether a matrix remains identical to its original form after applying a specific cyclic shifting operation exactly k times. We are given an m x n integer matrix mat , where m is the number of rows and n is the number of columns. Each row is processed differently depending...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2249 - Count Lattice Points Inside a Circle

LeetCode Problem 2249 Difficulty: 🟡 Medium Topics: Array, Hash Table, Math, Geometry, Enumeration Solution Problem Understanding The problem asks us to determine how many lattice points lie inside at least one of a set of circles on a 2D grid. Each circle is represented by a triplet [xi, yi, ri] , where (xi, yi) is the circle's center and ri is its radius. A lattice point is any point on...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3284 - Sum of Consecutive Subarrays

LeetCode Problem 3284 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Dynamic Programming Solution Problem Understanding The problem asks us to compute the sum of all consecutive subarrays in a given integer array nums . A consecutive subarray is defined as one where each element differs from the previous by exactly 1 or -1. This means the sequence can strictly increase or strictly decrease by 1 at each step. Subarrays of...

Practice › LeetCode › LeetCode 30xx ›

LeetCode 3022 - Minimize OR of Remaining Elements Using Operations

LeetCode Problem 3022 Difficulty: 🔴 Hard Topics: Array, Greedy, Bit Manipulation Solution Problem Understanding The problem presents an array nums of non-negative integers and an integer k . You are allowed to perform at most k operations, where each operation merges two adjacent elements using the bitwise AND operator. The goal is to minimize the bitwise OR of all remaining elements after performing these operations. Formally, if nums = [a_0,...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2014 - Longest Subsequence Repeated k Times

LeetCode Problem 2014 Difficulty: 🔴 Hard Topics: Hash Table, Two Pointers, String, Backtracking, Counting, Enumeration Solution Problem Understanding The problem asks us to find the longest subsequence of a string s that can be repeated k times while still being a subsequence of s . A subsequence is derived by deleting zero or more characters from a string without changing the order of the remaining characters. A subsequence seq repeated...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2919 - Minimum Increment Operations to Make Array Beautiful

LeetCode Problem 2919 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding The problem asks us to transform an input integer array nums into a beautiful array by performing a minimum number of increment operations. An increment operation increases a single element of nums by 1. The array is considered beautiful if every contiguous subarray of length 3 or more has a maximum element greater than or equal to...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1978 - Employees Whose Manager Left the Company

LeetCode Problem 1978 Difficulty: 🟢 Easy Topics: Database Solution Problem Understanding The problem is asking us to find employees in a company who meet two specific conditions. First, their salary must be strictly less than $30,000. Second, their manager has left the company, meaning there is no corresponding row for the manager in the Employees table even though the manager_id field in the employee's record still references that manager. The...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2802 - Find The K-th Lucky Number

LeetCode Problem 2802 Difficulty: 🟡 Medium Topics: Math, String, Bit Manipulation Solution Problem Understanding This problem asks us to find the k-th lucky number , where a lucky number is defined as an integer consisting only of the digits 4 and 7 . For example, the sequence of lucky numbers in increasing order starts as 4, 7, 44, 47, 74, 77, 444, and so on. The input is a single...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2699 - Modify Graph Edge Weights

LeetCode Problem 2699 Difficulty: 🔴 Hard Topics: Graph Theory, Heap (Priority Queue), Shortest Path Solution You asked for a complete guide, but the previous message included two different LeetCode problems with full requirements: LeetCode 2692 - Make Object Immutable LeetCode 2699 - Modify Graph Edge Weights A full reference-quality guide for either one is quite large and should be delivered independently to maintain quality and follow your formatting requirements exactly....

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3361 - Shift Distance Between Two Strings

LeetCode Problem 3361 Difficulty: 🟡 Medium Topics: Array, String, Prefix Sum Solution Problem Understanding The problem gives us two strings, s and t , of equal length. We want to transform s into t character by character using cyclic alphabet shifts. For every character in s , we are allowed to repeatedly perform one of two operations: Shift the character forward to the next letter in the alphabet. Shift the...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2090 - K Radius Subarray Averages

LeetCode Problem 2090 Difficulty: 🟡 Medium Topics: Array, Sliding Window Solution Problem Understanding The problem asks us to compute a special average for every index in the array. For each position i , we want to look at a subarray centered at i with radius k . That means we include all elements from index i - k through i + k , inclusive. The size of this window is...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2471 - Minimum Number of Operations to Sort a Binary Tree by Level

LeetCode Problem 2471 Difficulty: 🟡 Medium Topics: Tree, Breadth-First Search, Binary Tree Solution Problem Understanding The problem asks us to determine the minimum number of swap operations required to sort the values of a binary tree level by level in strictly increasing order. Specifically, at each level of the tree, we can only swap values of nodes that exist on that level. The tree is given as a standard binary...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3223 - Minimum Length of String After Operations

LeetCode Problem 3223 Difficulty: 🟡 Medium Topics: Hash Table, String, Counting Solution Problem Understanding The problem asks us to repeatedly remove characters from a string based on a specific rule. Specifically, for any character s[i] in the string, we can remove the nearest occurrence of the same character to the left of i and the nearest occurrence to the right of i . This operation can be applied any number...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2841 - Maximum Sum of Almost Unique Subarray

LeetCode Problem 2841 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sliding Window Solution LeetCode 2841 - Maximum Sum of Almost Unique Subarray Problem Understanding The problem gives us an integer array nums and two integers, m and k . We must examine every contiguous subarray whose length is exactly k . Among those subarrays, we only consider the ones that contain at least m distinct values. These are called almost...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2716 - Minimize String Length

LeetCode Problem 2716 Difficulty: 🟢 Easy Topics: Hash Table, String Solution Problem Understanding The problem asks us to minimize the length of a given string s by repeatedly performing two types of deletion operations. In the first operation, we can pick a character at some index and delete the closest identical character to its left if one exists. In the second operation, we can pick a character and delete the...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2928 - Distribute Candies Among Children I

LeetCode Problem 2928 Difficulty: 🟢 Easy Topics: Math, Combinatorics, Enumeration Solution Problem Understanding The problem asks us to calculate the number of ways to distribute n candies among exactly three children such that no child receives more than a specified limit of candies. In other words, we are looking for all integer triplets (a, b, c) such that a + b + c = n and each of a ,...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2298 - Tasks Count in the Weekend

LeetCode Problem 2298 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem provides a database table named Tasks , where each row represents a submitted task. Every task contains three fields: task_id , the unique identifier for the task assignee_id , the user assigned to the task submit_date , the date the task was submitted The goal is to compute two aggregated counts: weekend_cnt , the number of tasks...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3290 - Maximum Multiplication Score

LeetCode Problem 3290 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution LeetCode 3290 - Maximum Multiplication Score Problem Understanding This problem gives us two integer arrays: a , which always has exactly 4 elements. b , which has length at least 4 and can be as large as 100,000 . We must select exactly four indices from b : $$i_0 < i_1 < i_2 < i_3$$ The score obtained from...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2663 - Lexicographically Smallest Beautiful String

LeetCode Problem 2663 Difficulty: 🔴 Hard Topics: String, Greedy Solution Problem Understanding The problem requires generating the lexicographically smallest beautiful string that is strictly larger than a given beautiful string s . A string is beautiful if it uses only the first k letters of the English alphabet and contains no palindromic substring of length 2 or more. Essentially, no two consecutive letters can be the same, and no three...

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LeetCode 2606 - Find the Substring With Maximum Cost

LeetCode Problem 2606 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Dynamic Programming Solution Problem Understanding The problem asks us to find the substring of a given string s that maximizes a custom cost function. Each character in the string has a value: if it exists in the string chars , its value is taken from the corresponding index in the array vals ; if it does not exist in...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3316 - Find Maximum Removals From Source String

LeetCode Problem 3316 Difficulty: 🟡 Medium Topics: Array, Hash Table, Two Pointers, String, Dynamic Programming Solution LeetCode 3316 - Find Maximum Removals From Source String Problem Understanding We are given three inputs: source , the original string of length n pattern , a string that is guaranteed to already be a subsequence of source targetIndices , a sorted list of indices in source that are eligible for removal An operation...

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LeetCode 1997 - First Day Where You Have Been in All the Rooms

LeetCode Problem 1997 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding The problem describes a scenario where you visit a sequence of n rooms, starting from room 0 on day 0 . The order of subsequent visits is determined by a rule that depends on how many times you have visited the current room. Specifically, if your visit count for a room is odd , you move to...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2554 - Maximum Number of Integers to Choose From a Range I

LeetCode Problem 2554 Difficulty: 🟡 Medium Topics: Array, Hash Table, Binary Search, Greedy, Sorting Solution Problem Understanding The problem gives us three inputs: banned , an array of integers that are not allowed to be selected n , which defines the valid integer range [1, n] maxSum , the maximum total sum allowed for all chosen integers We must choose as many distinct integers as possible while satisfying four conditions:...

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LeetCode 3400 - Maximum Number of Matching Indices After Right Shifts

LeetCode Problem 3400 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Simulation Solution Problem Understanding The problem gives us two arrays, nums1 and nums2 , both of the same length n . We are allowed to repeatedly perform a right circular shift on nums1 . A right shift moves every element one position to the right, and the last element wraps around to the beginning. For example: [1, 2, 3, 4]...

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LeetCode 2634 - Filter Elements from Array

LeetCode Problem 2634 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding The problem asks us to implement a function that filters an array based on a custom condition defined by another function fn . The input consists of an integer array arr and a filtering function fn that can accept either one argument, the array element itself, or two arguments, the element and its index. The goal is to return...

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LeetCode 2424 - Longest Uploaded Prefix

LeetCode Problem 2424 Difficulty: 🟡 Medium Topics: Hash Table, Binary Search, Union-Find, Design, Binary Indexed Tree, Segment Tree, Heap (Priority Queue), Ordered Set Solution Problem Understanding The problem asks us to design a data structure that tracks uploaded videos and continuously reports the length of the longest uploaded prefix. A prefix of uploaded videos means that every video from 1 through i has already been uploaded. The goal is to...

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LeetCode 3303 - Find the Occurrence of First Almost Equal Substring

LeetCode Problem 3303 Difficulty: 🔴 Hard Topics: String, String Matching Solution Problem Understanding We are given two strings, s and pattern . The task is to find the smallest starting index in s such that the substring of length len(pattern) is "almost equal" to pattern . Two strings are considered almost equal if we can modify at most one character in one string to make the two strings identical. That...

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LeetCode 1931 - Painting a Grid With Three Different Colors

LeetCode Problem 1931 Difficulty: 🔴 Hard Topics: Dynamic Programming Solution Problem Understanding The problem is asking us to count the number of ways to paint an m x n grid using three colors: red, green, and blue, with the constraint that no two adjacent cells can have the same color . Adjacent cells include both vertically and horizontally neighboring cells. The inputs m and n define the number of rows...

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LeetCode 2165 - Smallest Value of the Rearranged Number

LeetCode Problem 2165 Difficulty: 🟡 Medium Topics: Math, Sorting Solution Problem Understanding In this problem, we are given an integer num , which may be positive, negative, or zero. Our goal is to rearrange its digits so that the resulting number is as small as possible while preserving the original sign. The important detail is that the sign cannot change. If the number is positive, the rearranged number must also...

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LeetCode 2859 - Sum of Values at Indices With K Set Bits

LeetCode Problem 2859 Difficulty: 🟢 Easy Topics: Array, Bit Manipulation Solution Problem Understanding The problem asks us to compute the sum of elements in an array, but not based on the values themselves. Instead, we decide whether to include an element by examining the binary representation of its index . You are given a 0-indexed integer array nums and an integer k . For each index i in the array,...

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LeetCode 3091 - Apply Operations to Make Sum of Array Greater Than or Equal to k

LeetCode Problem 3091 Difficulty: 🟡 Medium Topics: Math, Greedy, Enumeration Solution Problem Understanding The problem gives us a single positive integer k . We start with an array containing exactly one element: nums = [1] We are allowed to perform two kinds of operations any number of times: Increase the value of any existing element by 1 Duplicate any existing element and append the duplicate to the array Our goal...

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LeetCode 2840 - Check if Strings Can be Made Equal With Operations II

LeetCode Problem 2840 Difficulty: 🟡 Medium Topics: Hash Table, String, Sorting Solution Problem Understanding The problem asks us to determine whether two strings s1 and s2 of equal length can be made identical using a specific type of swap operation. The operation allows us to choose any two indices i and j such that i < j and j - i is even , and then swap the characters at...

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LeetCode 2978 - Symmetric Coordinates

LeetCode Problem 2978 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem asks us to identify symmetric coordinate pairs from a database table called Coordinates . Each row in the table represents a coordinate (X, Y) , and duplicate rows are allowed. Two coordinates are considered symmetric if they satisfy the following condition: (X1, Y1) and (X2, Y2) are symmetric when X1 == Y2 and X2 == Y1 In...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2216 - Minimum Deletions to Make Array Beautiful

LeetCode Problem 2216 Difficulty: 🟡 Medium Topics: Array, Stack, Greedy Solution Problem Understanding The problem asks us to transform a given integer array nums into a beautiful array using the minimum number of deletions. A beautiful array satisfies two conditions: its length is even, and no two consecutive elements at even indices are equal ( nums[i] != nums[i + 1] for all i % 2 == 0 ). Deletions are...

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LeetCode 2226 - Maximum Candies Allocated to K Children

LeetCode Problem 2226 Difficulty: 🟡 Medium Topics: Array, Binary Search Solution Problem Understanding This problem asks us to determine the largest number of candies that every child can receive equally , given a collection of candy piles and a number of children k . We are given an integer array candies , where candies[i] represents the size of the i-th pile. We are allowed to split a pile into smaller...

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LeetCode 2983 - Palindrome Rearrangement Queries

LeetCode Problem 2983 Difficulty: 🔴 Hard Topics: Hash Table, String, Prefix Sum Solution Problem Understanding We are given a string s of even length n . For every query, we are allowed to independently rearrange two specific substrings: One substring lies completely inside the left half of the string. The other substring lies completely inside the right half of the string. The goal is to determine whether, after rearranging only...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2858 - Minimum Edge Reversals So Every Node Is Reachable

LeetCode Problem 2858 Difficulty: 🔴 Hard Topics: Dynamic Programming, Depth-First Search, Breadth-First Search, Graph Theory Solution Problem Understanding This problem gives us a directed graph with n nodes and exactly n - 1 edges. The important guarantee is that if we ignore the direction of every edge, the graph becomes a tree. That means the underlying structure is connected and acyclic. Each edge is currently directed one way. For every...

Practice › LeetCode › LeetCode 31xx ›

LeetCode 3120 - Count the Number of Special Characters I

LeetCode Problem 3120 Difficulty: 🟢 Easy Topics: Hash Table, String Solution Problem Understanding The problem asks us to count the number of special characters in a given string word . A character is defined as special if it appears in both lowercase and uppercase forms within the same string. For example, if 'a' appears as both 'a' and 'A' anywhere in word , then 'a' counts as a special character....

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2481 - Minimum Cuts to Divide a Circle

LeetCode Problem 2481 Difficulty: 🟢 Easy Topics: Math, Geometry Solution Problem Understanding The problem asks for the minimum number of straight cuts required to divide a circle into n equal slices . A valid cut can either pass through the center and touch two points on the circle, or touch one point on the circle and pass through the center. The input is a single integer n representing the desired...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2837 - Total Traveled Distance

LeetCode Problem 2837 Difficulty: 🟢 Easy Topics: Database Solution Problem Understanding The problem requires calculating the total distance traveled by each user based on ride data stored in a relational database. We are given two tables: Users and Rides . The Users table contains user_id and name , where user_id is unique. The Rides table contains ride_id , user_id , and distance , where ride_id is unique. Each row in...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2279 - Maximum Bags With Full Capacity of Rocks

LeetCode Problem 2279 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting Solution Problem Understanding The problem presents n bags, each with a defined maximum capacity and a current number of rocks. The input consists of two arrays: capacity and rocks , where capacity[i] is the maximum number of rocks bag i can hold, and rocks[i] is how many rocks are currently in that bag. Additionally, you are given an integer additionalRocks...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2378 - Choose Edges to Maximize Score in a Tree

LeetCode Problem 2378 Difficulty: 🟡 Medium Topics: Dynamic Programming, Tree, Depth-First Search Solution This will be very large if done comprehensively and correctly under your formatting rules, likely exceeding a practical single-message limit and risking truncation or reduced quality. To preserve completeness and detail, I will split it into two contiguous parts while still covering every required section in full: Part 1 Problem Understanding Approaches Algorithm Walkthrough Python Solution Go...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1865 - Finding Pairs With a Certain Sum

LeetCode Problem 1865 Difficulty: 🟡 Medium Topics: Array, Hash Table, Design Solution Problem Understanding This problem asks us to design a mutable data structure that supports two operations efficiently over two arrays, nums1 and nums2 . The first array, nums1 , is fixed after initialization and never changes. The second array, nums2 , is mutable, meaning its elements can be updated through add(index, val) operations. The goal of the data...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3336 - Find the Number of Subsequences With Equal GCD

LeetCode Problem 3336 Difficulty: 🔴 Hard Topics: Array, Math, Dynamic Programming, Number Theory Solution Problem Understanding The problem asks us to count the number of pairs of non-empty disjoint subsequences from a given array nums such that the GCD of the elements in each subsequence of the pair is equal. A subsequence is a sequence that can be derived from the array by deleting zero or more elements without changing...

Practice › LeetCode › LeetCode 31xx ›

LeetCode 3134 - Find the Median of the Uniqueness Array

LeetCode Problem 3134 Difficulty: 🔴 Hard Topics: Array, Hash Table, Binary Search, Sliding Window Solution Problem Understanding The problem defines a special array called the uniqueness array. For every possible subarray of nums , we compute how many distinct values appear inside that subarray. We then collect all of those distinct counts into a single array and sort it in non decreasing order. The task is to return the median...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3259 - Maximum Energy Boost From Two Drinks

LeetCode Problem 3259 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding This problem is asking you to plan the consumption of two energy drinks over n hours to maximize the total energy boost. Each drink has a known energy contribution per hour, given by two arrays, energyDrinkA and energyDrinkB . You can drink only one energy drink per hour. However, if you switch from one drink to another,...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2262 - Total Appeal of A String

LeetCode Problem 2262 Difficulty: 🔴 Hard Topics: Hash Table, String, Dynamic Programming Solution Problem Understanding The problem asks us to calculate the total appeal of all substrings of a given string s . The appeal of a string is defined as the number of distinct characters it contains. In other words, for every possible substring of s , we need to count how many unique letters it has and sum...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2050 - Parallel Courses III

LeetCode Problem 2050 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Graph Theory, Topological Sort Solution Problem Understanding The problem asks us to determine the minimum number of months required to complete all courses given prerequisite relationships and the time each course takes. Each course is labeled from 1 to n , and relations describes which courses must be completed before others. The time array provides the duration of each course,...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3370 - Smallest Number With All Set Bits

LeetCode Problem 3370 Difficulty: 🟢 Easy Topics: Math, Bit Manipulation Solution Problem Understanding The problem asks us to find the smallest integer x such that: x >= n Every bit in the binary representation of x is set to 1 A number whose binary representation contains only set bits looks like this: 1 → binary "1" 3 → binary "11" 7 → binary "111" 15 → binary "1111" These numbers...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2819 - Minimum Relative Loss After Buying Chocolates

LeetCode Problem 2819 Difficulty: 🔴 Hard Topics: Array, Binary Search, Sorting, Prefix Sum Solution LeetCode 2819 - Minimum Relative Loss After Buying Chocolates Problem Understanding We are given an array prices , where each value represents the price of a chocolate. For every query [k, m] , Bob wants to choose exactly m chocolates. The payment rule depends on the threshold k : If a chocolate costs at most k...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2097 - Valid Arrangement of Pairs

LeetCode Problem 2097 Difficulty: 🔴 Hard Topics: Array, Depth-First Search, Graph Theory, Eulerian Circuit Solution LeetCode 2097 - Valid Arrangement of Pairs Problem Understanding This problem gives us a list of directed pairs, where each pair [starti, endi] represents a directed edge from starti to endi . We must rearrange all pairs so that adjacent pairs connect correctly. More specifically, if the arrangement is: [a, b], [c, d], [e, f]...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2659 - Make Array Empty

LeetCode Problem 2659 Difficulty: 🔴 Hard Topics: Array, Binary Search, Greedy, Binary Indexed Tree, Segment Tree, Sorting, Ordered Set Solution LeetCode 2659 - Make Array Empty Problem Understanding The problem gives us an array of distinct integers and defines two possible operations: If the first element is currently the smallest value in the array, we remove it. Otherwise, we move the first element to the end of the array. We...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1907 - Count Salary Categories

LeetCode Problem 1907 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem asks us to classify bank accounts into three salary categories based on their monthly income, then count how many accounts belong to each category. The input is a database table named Accounts . Each row contains two columns: account_id , which uniquely identifies a bank account income , which represents the monthly income associated with that account...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2624 - Snail Traversal

LeetCode Problem 2624 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding The problem asks us to take a 1D array of integers and convert it into a 2D matrix of specified dimensions, rowsCount and colsCount , following a snail traversal order by columns . Unlike a typical row-wise filling, the snail traversal order here moves column by column: the first column is filled top to bottom, the second column bottom...

Practice › LeetCode › LeetCode 31xx ›

LeetCode 3131 - Find the Integer Added to Array I

LeetCode Problem 3131 Difficulty: 🟢 Easy Topics: Array Solution LeetCode 3131 - Find the Integer Added to Array I Problem Understanding The problem gives us two integer arrays, nums1 and nums2 , which have the same length. We are told that every element in nums1 was modified by adding the same integer x , and after this transformation the resulting array became equal to nums2 . The word "equal" here...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2875 - Minimum Size Subarray in Infinite Array

LeetCode Problem 2875 Difficulty: 🟡 Medium Topics: Array, Hash Table, Sliding Window, Prefix Sum Solution LeetCode 2875 - Minimum Size Subarray in Infinite Array Problem Understanding This problem gives us a finite array nums , but asks us to imagine an infinite array called infinite_nums created by repeating nums forever. For example: nums = [1, 2, 3] infinite_nums = [1,2,3,1,2,3,1,2,3,1,2,3,...] We must find the shortest contiguous subarray in this infinite...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2725 - Interval Cancellation

LeetCode Problem 2725 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding This problem asks us to implement a function cancellable that repeatedly calls a given function fn with a set of arguments args at a fixed interval t milliseconds and allows this repeated execution to be stopped by a cancel function cancelFn . The first call to fn happens immediately (at time 0), and subsequent calls occur every t milliseconds....

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2558 - Take Gifts From the Richest Pile

LeetCode Problem 2558 Difficulty: 🟢 Easy Topics: Array, Heap (Priority Queue), Simulation Solution Problem Understanding The problem presents a scenario where we have multiple piles of gifts, represented as an integer array gifts , with each element indicating the number of gifts in that pile. Every second, you must choose the pile with the most gifts and reduce its count to the floor of its square root. The operation is...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2474 - Customers With Strictly Increasing Purchases

LeetCode Problem 2474 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding The problem gives us an Orders table where each row represents a purchase made by a customer. Every order has an order_id , a customer_id , an order_date , and a price . We need to find all customers whose yearly total purchases are strictly increasing from their first purchase year to their last purchase year. The key detail...

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LeetCode 2564 - Substring XOR Queries

LeetCode Problem 2564 Difficulty: 🟡 Medium Topics: Array, Hash Table, String, Bit Manipulation Solution Problem Understanding The problem gives us a binary string s and a list of queries. Each query contains two integers, first and second . For every query, we need to find a substring of s whose decimal value satisfies: $$val \oplus first = second$$ where ⊕ represents the bitwise XOR operation. We can rearrange the equation...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2595 - Number of Even and Odd Bits

LeetCode Problem 2595 Difficulty: 🟢 Easy Topics: Bit Manipulation Solution Problem Understanding The problem asks us to analyze the binary representation of a positive integer n and count how many 1 bits appear at even indices and how many appear at odd indices. Bit positions are counted from right to left , starting at index 0 . This means the least significant bit, the rightmost bit, is at index 0...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1882 - Process Tasks Using Servers

LeetCode Problem 1882 Difficulty: 🟡 Medium Topics: Array, Heap (Priority Queue) Solution Problem Understanding This problem asks us to simulate a task scheduling system with two priority rules. We are given a list of servers and a list of tasks. Each server has a weight, and each task has a processing duration. At second j , task j becomes available and enters a queue. Tasks must always be assigned in...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3306 - Count of Substrings Containing Every Vowel and K Consonants II

LeetCode Problem 3306 Difficulty: 🟡 Medium Topics: Hash Table, String, Sliding Window Solution Problem Understanding The problem asks us to count how many substrings of a given string satisfy two conditions simultaneously: The substring contains all five vowels, 'a' , 'e' , 'i' , 'o' , and 'u' , at least once. The substring contains exactly k consonants. The input consists of: A lowercase English string word A non-negative integer...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2573 - Find the String with LCP

LeetCode Problem 2573 Difficulty: 🔴 Hard Topics: Array, String, Dynamic Programming, Greedy, Union-Find, Matrix Solution Problem Understanding The problem gives us an n x n matrix called lcp , where: lcp[i][j] represents the length of the longest common prefix between: the suffix starting at index i the suffix starting at index j If the unknown string is word , then: suffix i is word[i:] suffix j is word[j:] The task...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2449 - Minimum Number of Operations to Make Arrays Similar

LeetCode Problem 2449 Difficulty: 🔴 Hard Topics: Array, Greedy, Sorting Solution LeetCode 2449 - Minimum Number of Operations to Make Arrays Similar Problem Understanding We are given two arrays, nums and target , of equal length. In a single operation, we choose two different indices and add 2 to one element while subtracting 2 from another element. This operation preserves the total sum of the array because every +2 is...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2219 - Maximum Sum Score of Array

LeetCode Problem 2219 Difficulty: 🟡 Medium Topics: Array, Prefix Sum Solution Problem Understanding The problem gives us a 0-indexed integer array nums of length n and asks us to compute the maximum sum score among all indices of the array. The sum score at index i is defined as the maximum of two sums: the sum of the first i + 1 elements of the array (the prefix sum up...

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LeetCode 2530 - Maximal Score After Applying K Operations

LeetCode Problem 2530 Difficulty: 🟡 Medium Topics: Array, Greedy, Heap (Priority Queue) Solution Problem Understanding The problem asks us to maximize a score after performing exactly k operations on an array of integers. Each operation allows us to choose any element nums[i] , add its value to the score, and then replace it with its ceiling division by 3. Essentially, every time we pick a number, it decreases for future...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2144 - Minimum Cost of Buying Candies With Discount

LeetCode Problem 2144 Difficulty: 🟢 Easy Topics: Array, Greedy, Sorting Solution Problem Understanding This problem asks us to minimize the total amount of money spent when buying candies under a special discount rule. For every two candies that are purchased, we may take one additional candy for free. However, the free candy must have a cost less than or equal to the cheaper of the two purchased candies. The input...

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LeetCode 2241 - Design an ATM Machine

LeetCode Problem 2241 Difficulty: 🟡 Medium Topics: Array, Greedy, Design Solution Problem Understanding The problem asks us to design a simulation of an ATM machine that can handle deposits and withdrawals with strict rules about how money is dispensed. The ATM stores five types of banknotes: $20, $50, $100, $200, and $500. The key challenge is implementing the withdrawal logic, which prioritizes giving out larger denominations first. The deposit function...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2760 - Longest Even Odd Subarray With Threshold

LeetCode Problem 2760 Difficulty: 🟢 Easy Topics: Array, Sliding Window Solution Problem Understanding The problem asks us to find the length of the longest contiguous subarray in a given integer array nums that satisfies three specific conditions. First, the subarray must start with an even number. Second, the subarray must alternate between even and odd numbers throughout its length. Third, every number in the subarray must be less than or...

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LeetCode 2258 - Escape the Spreading Fire

LeetCode Problem 2258 Difficulty: 🔴 Hard Topics: Array, Binary Search, Breadth-First Search, Matrix Solution Problem Understanding This problem asks us to determine how long we can safely wait before starting to move from the top-left corner of a grid to the bottom-right corner while a fire spreads across the grid over time. The grid contains three types of cells: 0 represents empty grass that both the player and the fire...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2431 - Maximize Total Tastiness of Purchased Fruits

LeetCode Problem 2431 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding This problem asks us to maximize the total tastiness of fruits we purchase while staying within a fixed budget. Each fruit has two attributes: a price and a tastiness value. We may either skip a fruit or buy it, but each fruit can only be purchased once. There is an additional twist: we are allowed to use...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2882 - Drop Duplicate Rows

LeetCode Problem 2882 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding The problem asks us to process a DataFrame representing customers and remove rows that have duplicate email addresses. Specifically, if multiple rows share the same email value, only the first occurrence should be kept, and all subsequent duplicates should be discarded. The input is a structured table with columns customer_id , name , and email . Each row represents...

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LeetCode 3236 - CEO Subordinate Hierarchy

LeetCode Problem 3236 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding This problem requires building a hierarchical view of a company's employee structure starting from the CEO. The Employees table contains employee records, including their unique ID, name, manager ID, and salary. The CEO is identified as the employee with a NULL manager_id . The task is to return all subordinates of the CEO, both direct and indirect , along...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2060 - Check if an Original String Exists Given Two Encoded Strings

LeetCode Problem 2060 Difficulty: 🔴 Hard Topics: String, Dynamic Programming Solution Problem Understanding The problem is asking us to determine whether there exists a single original string that could have been encoded into two different given strings, s1 and s2 . Each encoded string may contain letters and digits. The digits in an encoded string represent the length of some substring(s) in the original string, while letters represent literal characters...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1868 - Product of Two Run-Length Encoded Arrays

LeetCode Problem 1868 Difficulty: 🟡 Medium Topics: Array, Two Pointers Solution Problem Understanding This problem asks us to multiply two arrays that are already stored in run-length encoded form, without fully expanding them into normal arrays. A run-length encoded array stores consecutive repeated values compactly. Instead of explicitly storing every element, it stores pairs of: the value how many times it appears consecutively For example: [5,5,5,5,2,2] becomes: [[5,4],[2,2]] The task...

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LeetCode 2417 - Closest Fair Integer

LeetCode Problem 2417 Difficulty: 🟡 Medium Topics: Math, Enumeration Solution Problem Understanding In this problem, we are given a positive integer n , and we must find the smallest integer greater than or equal to n that is considered "fair". A number is fair when the count of even digits is exactly equal to the count of odd digits. For example: 10 is fair because it contains one even digit...

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LeetCode 3133 - Minimum Array End

LeetCode Problem 3133 Difficulty: 🟡 Medium Topics: Bit Manipulation Solution Problem Understanding The problem asks us to construct a strictly increasing array nums of length n such that the bitwise AND of all elements equals x . Among all valid arrays, we want to minimize the last element, nums[n - 1] . The constraints are important: Every element must be a positive integer. The array must be strictly increasing. The...

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LeetCode 2542 - Maximum Subsequence Score

LeetCode Problem 2542 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting, Heap (Priority Queue) Solution LeetCode 2542 - Maximum Subsequence Score Problem Understanding The problem gives us two integer arrays, nums1 and nums2 , both of the same length n , along with an integer k . We must choose exactly k indices from the arrays. The chosen indices form a subsequence, meaning the selected positions come from the original arrays...

Practice › LeetCode › LeetCode 30xx ›

LeetCode 3060 - User Activities within Time Bounds

LeetCode Problem 3060 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding The Sessions table stores information about user activity sessions on a platform. Each row represents a single session and contains: Column Meaning user_id The user who performed the session session_start When the session began session_end When the session ended session_id Unique identifier for the session session_type Either Viewer or Streamer The problem asks us to find every user who...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1900 - The Earliest and Latest Rounds Where Players Compete

LeetCode Problem 1900 Difficulty: 🔴 Hard Topics: Dynamic Programming, Memoization Solution Problem Understanding The tournament is organized as a sequence of elimination rounds. In every round, players are paired symmetrically from the two ends of the current lineup. The first player faces the last player, the second player faces the second-to-last player, and so on. If the number of players is odd, the middle player advances automatically without playing. The...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2937 - Make Three Strings Equal

LeetCode Problem 2937 Difficulty: 🟢 Easy Topics: String Solution Problem Understanding The problem asks us to make three strings s1 , s2 , and s3 identical by repeatedly deleting their rightmost characters. Each deletion is counted as one operation. The key restriction is that we cannot completely delete a string , so at least one character must remain in each string. If it is impossible to make all three strings...

Practice › LeetCode › LeetCode 21xx ›

LeetCode 2185 - Counting Words With a Given Prefix

LeetCode Problem 2185 Difficulty: 🟢 Easy Topics: Array, String, String Matching Solution Problem Understanding The problem gives us two inputs: An array of strings called words A string called pref We must count how many strings inside words start with the string pref . A prefix means the beginning portion of a string. For example: "at" is a prefix of "attention" "pay" is a prefix of "pay" "code" is not...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2877 - Create a DataFrame from List

LeetCode Problem 2877 Difficulty: 🟢 Easy Topics: — Solution LeetCode 2877 - Create a DataFrame from List Problem Understanding This problem asks us to create a Pandas DataFrame from a given two dimensional list named student_data . Each element of student_data is itself a list containing exactly two values: A student ID The student's age For example: [ [1, 15], [2, 11], [3, 11], [4, 20] ] represents four students....

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2373 - Largest Local Values in a Matrix

LeetCode Problem 2373 Difficulty: 🟢 Easy Topics: Array, Matrix Solution Problem Understanding The problem gives us an n x n square matrix called grid , where each cell contains an integer value. Our task is to construct a new matrix called maxLocal , whose dimensions are (n - 2) x (n - 2) . For every valid position in the output matrix, we examine a contiguous 3 x 3 submatrix...

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LeetCode 1994 - The Number of Good Subsets

LeetCode Problem 1994 Difficulty: 🔴 Hard Topics: Array, Hash Table, Math, Dynamic Programming, Bit Manipulation, Counting, Number Theory, Bitmask Solution LeetCode 1994 - The Number of Good Subsets Problem Understanding This problem asks us to count how many subsets of the input array have a product that can be written as a multiplication of distinct prime numbers. The phrase "distinct prime numbers" is the key restriction. A product is valid...

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LeetCode 3338 - Second Highest Salary II

LeetCode Problem 3338 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem asks us to analyze employee salary data within departments and extract all employees earning the second-highest salary in each department. The input is a table employees with three columns: emp_id , salary , and dept . Each emp_id is unique, but multiple employees may share the same salary in the same department. The output should list all...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2932 - Maximum Strong Pair XOR I

LeetCode Problem 2932 Difficulty: 🟢 Easy Topics: Array, Hash Table, Bit Manipulation, Trie, Sliding Window Solution Problem Understanding The problem gives us an integer array nums , and we must choose two numbers x and y from the array such that they form a strong pair . A pair is considered strong if: $$|x - y| \leq \min(x, y)$$ Among all valid strong pairs, we must compute the maximum possible...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1854 - Maximum Population Year

LeetCode Problem 1854 Difficulty: 🟢 Easy Topics: Array, Counting, Prefix Sum Solution Problem Understanding The problem asks us to determine the year with the highest population given a list of birth and death years. Each element in the input logs is a pair [birthi, deathi] representing the inclusive start of life at birthi and exclusive end at deathi . In other words, a person is considered alive from their birth...

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LeetCode 2510 - Check if There is a Path With Equal Number of 0's And 1's

LeetCode Problem 2510 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Matrix Solution Problem Understanding This problem asks us to determine if there exists a path in a binary matrix from the top-left corner (0, 0) to the bottom-right corner (m - 1, n - 1) such that the number of 0 s visited along the path is equal to the number of 1 s. The matrix is binary , so...

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LeetCode 2828 - Check if a String Is an Acronym of Words

LeetCode Problem 2828 Difficulty: 🟢 Easy Topics: Array, String Solution LeetCode 2828 - Check if a String Is an Acronym of Words Problem Understanding This problem asks us to determine whether a given string s is exactly the acronym formed from an array of words. An acronym is created by taking the first character from each word in the words array and concatenating those characters in the same order as...

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LeetCode 2087 - Minimum Cost Homecoming of a Robot in a Grid

LeetCode Problem 2087 Difficulty: 🟡 Medium Topics: Array, Greedy Solution Problem Understanding The problem gives us a robot located on a two dimensional grid. The robot starts at startPos = [startrow, startcol] and wants to reach homePos = [homerow, homecol] . The robot can move one cell at a time in four directions: up, down, left, and right. Unlike a standard shortest path problem where every move has the same...

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LeetCode 3098 - Find the Sum of Subsequence Powers

LeetCode Problem 3098 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Sorting Solution Problem Understanding The problem asks us to compute the sum of powers of all subsequences of length k from an array nums . A subsequence is any subset of elements taken in order from the array without reordering. The power of a subsequence is defined as the minimum absolute difference between any two elements in that subsequence. We...

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LeetCode 2305 - Fair Distribution of Cookies

LeetCode Problem 2305 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask Solution Problem Understanding The problem asks us to distribute a set of cookie bags among k children such that the unfairness of the distribution is minimized. Here, unfairness is defined as the maximum total number of cookies any single child receives . The input consists of an array cookies where cookies[i] represents the number of cookies...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2643 - Row With Maximum Ones

LeetCode Problem 2643 Difficulty: 🟢 Easy Topics: Array, Matrix Solution Here is the complete, detailed technical solution guide for LeetCode 2643 - Row With Maximum Ones following your exact formatting requirements. Problem Understanding The problem presents a binary matrix mat of size m x n , where each element is either 0 or 1 . The task is to identify the row that contains the maximum number of ones and...

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LeetCode 2116 - Check if a Parentheses String Can Be Valid

LeetCode Problem 2116 Difficulty: 🟡 Medium Topics: String, Stack, Greedy Solution Problem Understanding This problem asks whether a given parentheses string can be transformed into a valid parentheses sequence under certain constraints. We are given two strings: s , containing only '(' and ')' locked , containing only '0' and '1' Both strings have the same length n . At every index: If locked[i] == '1' , then s[i] is...

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LeetCode 3380 - Maximum Area Rectangle With Point Constraints I

LeetCode Problem 3380 Difficulty: 🟡 Medium Topics: Array, Math, Binary Indexed Tree, Segment Tree, Geometry, Sorting, Enumeration Solution LeetCode 3380 - Maximum Area Rectangle With Point Constraints I Problem Understanding The problem gives us a set of unique points on a 2D plane. We need to determine the largest possible axis-aligned rectangle that can be formed using exactly four of those points as its corners. An axis-aligned rectangle means: The...

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LeetCode 2273 - Find Resultant Array After Removing Anagrams

LeetCode Problem 2273 Difficulty: 🟢 Easy Topics: Array, Hash Table, String, Sorting Solution Problem Understanding This problem asks us to repeatedly remove words from an array when two adjacent words are anagrams of each other . We are given a 0-indexed string array words , where every string contains only lowercase English letters. During each operation, we may choose an index i such that the word at words[i] is an...

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LeetCode 2862 - Maximum Element-Sum of a Complete Subset of Indices

LeetCode Problem 2862 Difficulty: 🔴 Hard Topics: Array, Math, Number Theory Solution LeetCode 2862 - Maximum Element-Sum of a Complete Subset of Indices Problem Understanding The array nums is 1-indexed , meaning the first element corresponds to index 1 , the second element corresponds to index 2 , and so on. We want to select a subset of indices such that for every pair of selected indices i and j...

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LeetCode 2720 - Popularity Percentage

LeetCode Problem 2720 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding The Friends table stores friendship relationships between users on a social platform. Each row contains two user IDs, user1 and user2 , indicating that those two users are friends with each other. The task is to compute a popularity percentage for every user who appears anywhere in the table. The popularity percentage is defined as: $\text{Popularity Percentage} = \frac{\text{Number...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2038 - Remove Colored Pieces if Both Neighbors are the Same Color

LeetCode Problem 2038 Difficulty: 🟡 Medium Topics: Math, String, Greedy, Game Theory Solution Problem Understanding This problem describes a two-player game played on a line of colored pieces. The input colors is a string representing these pieces, where each character is either 'A' or 'B' . Alice always moves first and can only remove 'A' pieces that are surrounded on both sides by 'A' . Bob moves second and can...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3299 - Sum of Consecutive Subsequences

LeetCode Problem 3299 Difficulty: 🔴 Hard Topics: Array, Hash Table, Dynamic Programming Solution LeetCode 3299 - Sum of Consecutive Subsequences Problem Understanding We are given an array nums , and we must consider all non-empty subsequences of that array. A subsequence preserves the original order of elements, but elements do not need to be contiguous. A subsequence is considered consecutive if every adjacent pair differs by exactly +1 or exactly...

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LeetCode 3326 - Minimum Division Operations to Make Array Non Decreasing

LeetCode Problem 3326 Difficulty: 🟡 Medium Topics: Array, Math, Greedy, Number Theory Solution Problem Understanding The problem asks us to make a given integer array nums non-decreasing by performing a specific type of operation any number of times. Each operation consists of selecting an element and dividing it by its greatest proper divisor . A proper divisor of a number x is a positive integer less than x that divides...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2863 - Maximum Length of Semi-Decreasing Subarrays

LeetCode Problem 2863 Difficulty: 🟡 Medium Topics: Array, Stack, Sorting, Monotonic Stack Solution LeetCode 2863 - Maximum Length of Semi-Decreasing Subarrays Problem Understanding The problem gives us an integer array nums and asks for the length of the longest contiguous subarray whose first element is strictly greater than its last element. A subarray is any contiguous segment of the array. For a subarray nums[i...j] to be considered semi-decreasing, the following...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1984 - Minimum Difference Between Highest and Lowest of K Scores

LeetCode Problem 1984 Difficulty: 🟢 Easy Topics: Array, Sliding Window, Sorting Solution Problem Understanding The problem asks us to find the minimum possible difference between the highest and lowest scores when selecting exactly k scores from an array of student scores. The input is a 0-indexed integer array nums where each element represents a student's score, and an integer k which is the number of scores to pick. The expected...

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LeetCode 1989 - Maximum Number of People That Can Be Caught in Tag

LeetCode Problem 1989 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Greedy Solution Problem Understanding The problem describes a line of people represented by a binary array team , where each index corresponds to a person. A value of 1 indicates a person who is “it”, and a value of 0 indicates a person who is not “it”. Each “it” person can catch at most one non-“it” person, and only if...

Practice › LeetCode › LeetCode 30xx ›

LeetCode 3024 - Type of Triangle

LeetCode Problem 3024 Difficulty: 🟢 Easy Topics: Array, Math, Sorting Solution Problem Understanding The problem gives an integer array nums of length 3 , where each value represents the length of a side of a possible triangle. Our task is to determine what kind of triangle these three sides can form. There are four possible outputs: "equilateral" if all three sides are equal "isosceles" if exactly two sides are equal...

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LeetCode 3029 - Minimum Time to Revert Word to Initial State I

LeetCode Problem 3029 Difficulty: 🟡 Medium Topics: String, Rolling Hash, String Matching, Hash Function Solution Problem Understanding The problem gives us a string word and an integer k . Every second, we are forced to perform two operations in sequence: Remove the first k characters from the string. Append any k characters to the end of the string. The appended characters are completely under our control. They do not need...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2433 - Find The Original Array of Prefix Xor

LeetCode Problem 2433 Difficulty: 🟡 Medium Topics: Array, Bit Manipulation Solution Problem Understanding The problem is asking us to reverse-engineer an array arr from its prefix XOR array pref . Specifically, pref[i] represents the XOR of all elements in arr from index 0 to i . Our goal is to reconstruct arr given only pref . For instance, if pref = [5,2,0,3,1] , it means: pref[0] = arr[0] pref[1] =...

Practice › LeetCode › LeetCode 22xx ›

LeetCode 2283 - Check if Number Has Equal Digit Count and Digit Value

LeetCode Problem 2283 Difficulty: 🟢 Easy Topics: Hash Table, String, Counting Solution Problem Understanding This problem asks us to verify a self-descriptive property of a string of digits. You are given a string num of length n , where each character is a digit between '0' and '9'. The requirement is that for every index i in the string, the digit i must appear exactly num[i] times in the entire...

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LeetCode 2057 - Smallest Index With Equal Value

LeetCode Problem 2057 Difficulty: 🟢 Easy Topics: Array Solution Problem Understanding The problem gives us a 0-indexed integer array nums . We must find the smallest index i such that: $$i \bmod 10 = nums[i]$$ The expression i mod 10 means the remainder when i is divided by 10 . We are asked to scan the array and determine whether any index satisfies this condition. If multiple indices satisfy it,...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2883 - Drop Missing Data

LeetCode Problem 2883 Difficulty: 🟢 Easy Topics: — Solution LeetCode 2883 - Drop Missing Data Problem Understanding This problem provides a pandas DataFrame named students with three columns: Column Type student_id int name object age int Some rows contain missing values in the name column. In pandas, these missing values are represented as None or other null-like values. The task is to return a DataFrame that contains only the rows...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1971 - Find if Path Exists in Graph

LeetCode Problem 1971 Difficulty: 🟢 Easy Topics: Depth-First Search, Breadth-First Search, Union-Find, Graph Theory Solution Problem Understanding The problem asks us to determine whether a path exists between two nodes in an undirected graph. The graph is defined by n vertices labeled from 0 to n - 1 and a list of edges, where each edge connects two distinct vertices. The key points are that the graph is bi-directional ,...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2647 - Color the Triangle Red

LeetCode Problem 2647 Difficulty: 🔴 Hard Topics: Array, Math Solution Problem Understanding The problem asks us to determine the minimal set of initial triangles to color red in an equilateral triangle of side length n , such that by repeatedly applying a propagation rule, all triangles eventually become red. The propagation rule is simple: any white triangle with at least two red neighbors becomes red automatically. The input n specifies...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2692 - Make Object Immutable

LeetCode Problem 2692 Difficulty: 🟡 Medium Topics: — Solution Problem Understanding This problem asks us to create an immutable wrapper around a JSON object or array. The returned structure must behave exactly like the original data for read operations, but any attempt to mutate it must immediately throw a string error with a very specific format. The input can be either a plain object or an array, and because the...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1990 - Count the Number of Experiments

LeetCode Problem 1990 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding This problem gives us a database table named Experiments . Each row represents a single experiment performed by a participant. Every experiment belongs to one platform and one experiment category. The table contains three columns: Column Meaning experiment_id Unique identifier for the experiment platform One of Android , IOS , or Web experiment_name One of Reading , Sports ,...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2473 - Minimum Cost to Buy Apples

LeetCode Problem 2473 Difficulty: 🟡 Medium Topics: Array, Graph Theory, Heap (Priority Queue), Shortest Path Solution Problem Understanding The problem asks us to determine the minimum cost to buy exactly one apple starting from each city in a network of cities connected by bidirectional roads. Each city has a specific cost for buying an apple, and each road has a travel cost. After buying an apple, you must return to...

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LeetCode 2666 - Allow One Function Call

LeetCode Problem 2666 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding This problem asks us to create a wrapper around an existing function fn such that the wrapped version can only execute the original function one time. In other words, we are given a function fn , and we must return a new function. This returned function behaves exactly like fn during its first invocation, meaning it accepts the same...

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LeetCode 3010 - Divide an Array Into Subarrays With Minimum Cost I

LeetCode Problem 3010 Difficulty: 🟢 Easy Topics: Array, Sorting, Enumeration Solution Problem Understanding The problem asks us to split a given array nums into exactly three disjoint contiguous subarrays and minimize the sum of their costs . The important detail is how cost is defined. The cost of a subarray is simply its first element . For example: [1,2,3] has cost 1 [10,5] has cost 10 Since we must divide...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2900 - Longest Unequal Adjacent Groups Subsequence I

LeetCode Problem 2900 Difficulty: 🟢 Easy Topics: Array, String, Dynamic Programming, Greedy Solution LeetCode 2900 - Longest Unequal Adjacent Groups Subsequence I Problem Understanding We are given two arrays of the same length: words[i] is a string. groups[i] is either 0 or 1 . We want to select a subsequence of words . A subsequence preserves the original order of elements, but we may skip any number of elements. The...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2306 - Naming a Company

LeetCode Problem 2306 Difficulty: 🔴 Hard Topics: Array, Hash Table, String, Bit Manipulation, Enumeration Solution Problem Understanding The problem gives us a list of unique strings called ideas . We must repeatedly choose two different strings, swap their first characters, and determine whether the newly formed strings are both absent from the original list. If both newly generated names do not already exist in ideas , then the ordered pair...

Practice › LeetCode › LeetCode 19xx ›

LeetCode 1975 - Maximum Matrix Sum

LeetCode Problem 1975 Difficulty: 🟡 Medium Topics: Array, Greedy, Matrix Solution Problem Understanding The problem gives an n x n integer matrix and allows an operation where we pick any two adjacent cells (sharing a side) and multiply both values by -1 . This operation can be applied any number of times, and the goal is to maximize the total sum of all matrix elements after any sequence of such...

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LeetCode 3030 - Find the Grid of Region Average

LeetCode Problem 3030 Difficulty: 🟡 Medium Topics: Array, Matrix Solution Problem Understanding The problem gives us a grayscale image represented as an m x n matrix called image . Every value in the matrix is an integer between 0 and 255 , representing the intensity of a pixel. We must examine every possible 3 x 3 subgrid inside the image. A 3 x 3 subgrid is considered a valid region...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2988 - Manager of the Largest Department

LeetCode Problem 2988 Difficulty: 🟡 Medium Topics: Database Solution You included two different problems in one message, and the second prompt overrides the first at the end. I will answer for LeetCode 2988 - Manager of the Largest Department . Problem Understanding This problem asks us to identify the manager or managers of the department(s) with the highest employee count . We are given a single database table named Employees...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3208 - Alternating Groups II

LeetCode Problem 3208 Difficulty: 🟡 Medium Topics: Array, Sliding Window Solution LeetCode 3208 - Alternating Groups II Problem Understanding The problem gives us a circular array called colors , where each value represents a tile color. A value of 0 means red, and a value of 1 means blue. We are also given an integer k . We must count how many groups of exactly k contiguous tiles form an...

Practice › LeetCode › LeetCode 20xx ›

LeetCode 2073 - Time Needed to Buy Tickets

LeetCode Problem 2073 Difficulty: 🟢 Easy Topics: Array, Queue, Simulation Solution Problem Understanding This problem describes a queue of n people, each wanting to buy a certain number of tickets. The input is an array tickets where tickets[i] represents how many tickets the i-th person wants. The process works like a real-life queue: each person buys one ticket at a time , taking exactly 1 second per ticket , and...

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LeetCode 2239 - Find Closest Number to Zero

LeetCode Problem 2239 Difficulty: 🟢 Easy Topics: Array Solution Problem Understanding The problem gives us an integer array nums , and we need to return the number whose value is closest to 0 . The phrase "closest to zero" means we compare numbers using their absolute values. For example: |-2| = 2 |5| = 5 Since 2 < 5 , the number -2 is closer to zero than 5 ....

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LeetCode 2682 - Find the Losers of the Circular Game

LeetCode Problem 2682 Difficulty: 🟢 Easy Topics: Array, Hash Table, Simulation Solution Problem Understanding This problem describes a circular passing game among n friends numbered from 1 to n . The ball always starts with friend 1 , and each turn increases the number of clockwise steps by a multiple of k . More specifically: On the first turn, the current player passes the ball 1 * k steps clockwise....

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LeetCode 2376 - Count Special Integers

LeetCode Problem 2376 Difficulty: 🔴 Hard Topics: Math, Dynamic Programming Solution LeetCode 2376 - Count Special Integers Problem Understanding The problem asks us to count how many integers in the range [1, n] contain only distinct digits. A number is considered special if no digit appears more than once in its decimal representation. For example, the number 135 is special because the digits 1 , 3 , and 5 are...

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LeetCode 3075 - Maximize Happiness of Selected Children

LeetCode Problem 3075 Difficulty: 🟡 Medium Topics: Array, Greedy, Sorting Solution Problem Understanding The problem gives us an array happiness representing the happiness values of n children standing in a queue and asks us to select exactly k children to maximize the sum of their happiness. The twist is that each time we select a child, all unselected children have their happiness decreased by 1, but their happiness cannot go...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2994 - Friday Purchases II

LeetCode Problem 2994 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding The problem requires calculating the total spending by users on each Friday in November 2023 , broken down by week of the month . The input is a Purchases table containing user_id , purchase_date , and amount_spend . The output must include all Fridays in November, and for any Friday with no purchases, the total should be reported as...

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LeetCode 2950 - Number of Divisible Substrings

LeetCode Problem 2950 Difficulty: 🟡 Medium Topics: Hash Table, String, Counting, Prefix Sum Solution Problem Understanding The problem asks us to analyze a given string word where each lowercase English letter is mapped to a digit according to a classic phone keypad scheme. A substring of the string is considered divisible if the sum of the mapped digits of its characters is divisible by the length of the substring. The...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2726 - Calculator with Method Chaining

LeetCode Problem 2726 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding This problem asks us to design a class named Calculator that supports basic arithmetic operations while enabling method chaining . Method chaining means that after calling one method, we can immediately call another method on the same object. For example: new Calculator(10).add(5).subtract(7).getResult() works because each mathematical method returns the same Calculator instance after updating its internal state. The class...

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LeetCode 2890 - Reshape Data: Melt

LeetCode Problem 2890 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding This problem asks us to reshape a dataset from a wide format to a long format , also known as “melting” in data analysis. In the input DataFrame, each row represents a product, and each column beyond the first represents quarterly sales ( quarter_1 to quarter_4 ). The goal is to transform this data so that each row contains...

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LeetCode 3289 - The Two Sneaky Numbers of Digitville

LeetCode Problem 3289 Difficulty: 🟢 Easy Topics: Array, Hash Table, Math Solution Problem Understanding The problem is asking us to identify two numbers that appear twice in an otherwise consecutive list of integers ranging from 0 to n - 1 . In other words, the input nums is almost a permutation of the numbers 0 through n - 1 , except that two numbers are repeated , so the length...

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LeetCode 2702 - Minimum Operations to Make Numbers Non-positive

LeetCode Problem 2702 Difficulty: 🔴 Hard Topics: Array, Binary Search Solution Problem Understanding In this problem, we are given an array nums and two integers x and y , where x > y . During each operation, we choose one index i and apply two different decrements: nums[i] decreases by x every other element decreases by y The goal is to determine the minimum number of operations needed so that...

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LeetCode 2903 - Find Indices With Index and Value Difference I

LeetCode Problem 2903 Difficulty: 🟢 Easy Topics: Array, Two Pointers Solution Problem Understanding The problem asks us to find two indices i and j in the array such that two conditions are satisfied simultaneously : The indices must be far enough apart: $$|i - j| \geq indexDifference$$ The values at those indices must differ enough: $$|nums[i] - nums[j]| \geq valueDifference$$ We may return any valid pair if multiple answers exist....

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LeetCode 2925 - Maximum Score After Applying Operations on a Tree

LeetCode Problem 2925 Difficulty: 🟡 Medium Topics: Dynamic Programming, Tree, Depth-First Search Solution Problem Understanding The problem gives us an undirected tree with n nodes rooted at node 0 . Every node has an associated positive value. We may repeatedly perform an operation where we choose a node, add its current value to our score, and then permanently set that node's value to 0 . However, after all operations are...

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LeetCode 3213 - Construct String with Minimum Cost

LeetCode Problem 3213 Difficulty: 🔴 Hard Topics: Array, String, Dynamic Programming, Suffix Array Solution Problem Understanding The problem asks us to construct a target string target by repeatedly appending strings from a given array words , where each word has an associated cost in costs . The goal is to determine the minimum total cost to construct target exactly. If it is impossible to form target from the given words,...

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LeetCode 3194 - Minimum Average of Smallest and Largest Elements

LeetCode Problem 3194 Difficulty: 🟢 Easy Topics: Array, Two Pointers, Sorting Solution LeetCode 3194 - Minimum Average of Smallest and Largest Elements Problem Understanding The problem gives us an even-length integer array nums . We repeatedly perform the following operation until the array becomes empty: Remove the smallest element. Remove the largest element. Compute their average. Store that average in another array called averages . After all pairs have been...

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LeetCode 2731 - Movement of Robots

LeetCode Problem 2731 Difficulty: 🟡 Medium Topics: Array, Brainteaser, Sorting, Prefix Sum Solution LeetCode 2731 - Movement of Robots Problem Understanding The problem gives us a list of robots positioned on an infinite number line. Each robot starts at a unique coordinate from the array nums , and each robot has an associated movement direction from the string s . A robot moves exactly one unit per second. If the...

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LeetCode 2808 - Minimum Seconds to Equalize a Circular Array

LeetCode Problem 2808 Difficulty: 🟡 Medium Topics: Array, Hash Table Solution Problem Understanding The problem gives a circular array nums of length n . At each second, every element in the array can be replaced simultaneously by either itself, its previous neighbor, or its next neighbor. The task is to determine the minimum number of seconds required to make all elements equal. In simpler terms, the array elements "propagate" their...

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LeetCode 2197 - Replace Non-Coprime Numbers in Array

LeetCode Problem 2197 Difficulty: 🔴 Hard Topics: Array, Math, Stack, Number Theory Solution Problem Understanding The problem asks us to repeatedly replace adjacent non-coprime numbers in an array with their Least Common Multiple (LCM) until no more adjacent non-coprime pairs exist. Two numbers are non-coprime if their greatest common divisor (GCD) is greater than 1. The final array should be returned after all possible replacements. In other words, given an...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2545 - Sort the Students by Their Kth Score

LeetCode Problem 2545 Difficulty: 🟡 Medium Topics: Array, Sorting, Matrix Solution Problem Understanding In this problem, we are given a matrix named score with dimensions m x n . Each row represents a student, and each column represents an exam. The value score[i][j] is the score obtained by the i th student on the j th exam. The task is to sort the rows of the matrix according to the...

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LeetCode 2396 - Strictly Palindromic Number

LeetCode Problem 2396 Difficulty: 🟡 Medium Topics: Math, Two Pointers, Brainteaser Solution Problem Understanding The problem asks whether a given integer n is strictly palindromic . A number is strictly palindromic if, for every base b between 2 and n - 2 (inclusive), its representation in base b reads the same forwards and backwards. In simpler terms, you need to check all number systems from base 2 up to base...

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LeetCode 3285 - Find Indices of Stable Mountains

LeetCode Problem 3285 Difficulty: 🟢 Easy Topics: Array Solution Problem Understanding The problem asks us to find indices of "stable" mountains from a given array of mountain heights. Each element in the array represents the height of a mountain in sequence. A mountain is stable if the mountain immediately before it exists and has a height strictly greater than a given threshold. Notably, the first mountain at index 0 cannot...

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LeetCode 3103 - Find Trending Hashtags II

LeetCode Problem 3103 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding The problem gives us a database table named Tweets , where each row represents a tweet posted during February 2024. Every tweet contains plain text in the tweet column, and that text may contain one or more hashtags. A hashtag is a word that starts with the # character, such as #HappyDay or #TechLife . Our task is to...

Practice › LeetCode › LeetCode 24xx ›

LeetCode 2421 - Number of Good Paths

LeetCode Problem 2421 Difficulty: 🔴 Hard Topics: Array, Hash Table, Tree, Union-Find, Graph Theory, Sorting Solution Problem Understanding The problem is asking us to count the number of good paths in a tree. A tree is a connected acyclic graph with n nodes and n - 1 edges. Each node has an integer value assigned by the array vals . A good path is defined as a simple path (no...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3240 - Minimum Number of Flips to Make Binary Grid Palindromic II

LeetCode Problem 3240 Difficulty: 🟡 Medium Topics: Array, Two Pointers, Matrix Solution Problem Understanding We are given a binary matrix grid with m rows and n columns. Every cell contains either 0 or 1 . We may flip any cell, meaning we can change 0 to 1 or 1 to 0 . The goal is to perform the minimum number of flips such that two conditions become true simultaneously: Every...

Practice › LeetCode › LeetCode 33xx ›

LeetCode 3388 - Count Beautiful Splits in an Array

LeetCode Problem 3388 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming Solution Problem Understanding We are given an integer array nums , and we want to count how many ways we can split it into exactly three non-empty contiguous subarrays: nums1 nums2 nums3 such that: nums = nums1 + nums2 + nums3 where + means concatenation. A split is considered beautiful if at least one of these conditions holds: nums1 is...

Practice › LeetCode › LeetCode 28xx ›

LeetCode 2836 - Maximize Value of Function in a Ball Passing Game

LeetCode Problem 2836 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation Solution Problem Understanding This problem presents a ball-passing game among n players, represented by an array receiver of length n . Each element receiver[i] indicates which player receives the ball when player i passes it. The game starts by selecting a player i as the first to hold the ball. The ball is then passed k times according...

Practice › LeetCode › LeetCode 29xx ›

LeetCode 2996 - Smallest Missing Integer Greater Than Sequential Prefix Sum

LeetCode Problem 2996 Difficulty: 🟢 Easy Topics: Array, Hash Table, Sorting Solution Problem Understanding The problem asks us to find the smallest missing integer in the array that is greater than or equal to the sum of the longest sequential prefix . A sequential prefix means the beginning part of the array where every number increases by exactly 1 compared to the previous number. Formally, for a prefix nums[0..i] ,...

Practice › LeetCode › LeetCode 30xx ›

LeetCode 3037 - Find Pattern in Infinite Stream II

LeetCode Problem 3037 Difficulty: 🔴 Hard Topics: Array, Sliding Window, Rolling Hash, String Matching, Interactive, Hash Function Solution Problem Understanding The problem requires us to detect the first occurrence of a binary pattern within a theoretically infinite stream of bits. The stream is accessed sequentially using the next() method, which returns one bit at a time. Our task is to determine the index in the stream where the given pattern...

Practice › LeetCode › LeetCode 30xx ›

LeetCode 3013 - Divide an Array Into Subarrays With Minimum Cost II

LeetCode Problem 3013 Difficulty: 🔴 Hard Topics: Array, Hash Table, Sliding Window, Heap (Priority Queue) Solution Problem Understanding The problem asks us to divide a given array nums into k contiguous subarrays in a very specific way. Each subarray has a cost defined as its first element. The objective is to minimize the total cost , which is the sum of the first elements of all k subarrays. The challenge...

Practice › LeetCode › LeetCode 26xx ›

LeetCode 2629 - Function Composition

LeetCode Problem 2629 Difficulty: 🟢 Easy Topics: — Solution Problem Understanding This problem asks us to implement function composition . We are given an array of functions and must return a new function that combines all of them into a single callable function. In mathematics and programming, function composition means taking the output of one function and feeding it into the next. The important detail here is that the functions...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3276 - Select Cells in Grid With Maximum Score

LeetCode Problem 3276 Difficulty: 🔴 Hard Topics: Array, Dynamic Programming, Bit Manipulation, Matrix, Bitmask Solution Problem Understanding The problem requires us to select cells from a 2D matrix grid such that no two selected cells are in the same row, and all selected values are unique. Our goal is to maximize the sum of these selected values. In other words, for each row, we can choose at most one value,...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2752 - Customers with Maximum Number of Transactions on Consecutive Days

LeetCode Problem 2752 Difficulty: 🔴 Hard Topics: Database Solution Problem Understanding The problem gives us a database table named Transactions . Each row represents a transaction made by a customer on a specific date. The important detail is that the pair (customer_id, transaction_date) is guaranteed to be unique, which means a customer can make at most one transaction per day. We need to determine which customers achieved the maximum number...

Practice › LeetCode › LeetCode 18xx ›

LeetCode 1896 - Minimum Cost to Change the Final Value of Expression

LeetCode Problem 1896 Difficulty: 🔴 Hard Topics: Math, String, Dynamic Programming, Stack Solution Problem Understanding This problem gives us a boolean expression containing only: '0' and '1' binary operators '&' and '|' parentheses The expression is guaranteed to be valid, which means every operator has valid operands and every parenthesis is properly matched. The important detail is that the expression is not evaluated using normal operator precedence. Instead: Parentheses are...

Practice › LeetCode › LeetCode 32xx ›

LeetCode 3220 - Odd and Even Transactions

LeetCode Problem 3220 Difficulty: 🟡 Medium Topics: Database Solution Problem Understanding The problem provides a database table named transactions , where each row represents a transaction with three fields: transaction_id , a unique identifier amount , the transaction amount transaction_date , the date on which the transaction occurred For every distinct transaction_date , we need to compute two separate sums: odd_sum , the total amount of all transactions whose amount...

Practice › LeetCode › LeetCode 23xx ›

LeetCode 2310 - Sum of Numbers With Units Digit K

LeetCode Problem 2310 Difficulty: 🟡 Medium Topics: Math, Dynamic Programming, Greedy, Enumeration Solution Problem Understanding This problem asks us to construct a set of positive integers such that: Every number in the set has a units digit equal to k . The sum of all numbers equals num . We want the smallest possible number of integers in the set. If it is impossible to create such a set, we...

Practice › LeetCode › LeetCode 27xx ›

LeetCode 2708 - Maximum Strength of a Group

LeetCode Problem 2708 Difficulty: 🟡 Medium Topics: Array, Dynamic Programming, Backtracking, Greedy, Bit Manipulation, Sorting, Enumeration Solution Problem Understanding The problem asks us to select a non-empty subset of integers from a given array nums such that the product of the numbers in the subset is maximized. Each number represents a student’s exam score, and the subset represents a group of students. The "strength" of a group is the product...

Practice › LeetCode › LeetCode 25xx ›

LeetCode 2501 - Longest Square Streak in an Array

LeetCode Problem 2501 Difficulty: 🟡 Medium Topics: Array, Hash Table, Binary Search, Dynamic Programming, Sorting Solution Problem Understanding The problem asks us to identify the longest square streak in an array of integers nums . A square streak is a subsequence of at least length 2 where, after sorting, every element is the square of the previous element. In other words, if the sorted subsequence is [x1, x2, ..., xk]...

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LeetCode 3922 - Minimum Flips to Make Binary String Coherent

LeetCode 3924 - Minimum Threshold Path With Limited Heavy Edges

LeetCode 3899 - Angles of a Triangle

LeetCode 3933 - Largest Local Values in a Matrix II

LeetCode 3926 - Count Valid Word Occurrences

LeetCode 3891 - Minimum Increase to Maximize Special Indices

LeetCode 3843 - First Element with Unique Frequency

LeetCode 3687 - Library Late Fee Calculator

LeetCode 3672 - Sum of Weighted Modes in Subarrays

LeetCode 3753 - Total Waviness of Numbers in Range II

LeetCode 3761 - Minimum Absolute Distance Between Mirror Pairs

LeetCode 3666 - Minimum Operations to Equalize Binary String

LeetCode 3656 - Determine if a Simple Graph Exists

LeetCode 3650 - Minimum Cost Path with Edge Reversals

LeetCode 3645 - Maximum Total from Optimal Activation Order

LeetCode 3631 - Sort Threats by Severity and Exploitability

LeetCode 3581 - Count Odd Letters from Number

LeetCode 3575 - Maximum Good Subtree Score

LeetCode 3576 - Transform Array to All Equal Elements

LeetCode 3473 - Sum of K Subarrays With Length at Least M

LeetCode 3485 - Longest Common Prefix of K Strings After Removal

LeetCode 3410 - Maximize Subarray Sum After Removing All Occurrences of One Element

LeetCode 3455 - Shortest Matching Substring

LeetCode 3943 - Number of Pairs After Increment

LeetCode 3942 - Minimum Operations to Sort a Permutation

LeetCode 3940 - Limit Occurrences in Sorted Array

LeetCode 3941 - Password Strength

LeetCode 3937 - Minimum Operations to Make Array Modulo Alternating I

LeetCode 3938 - Maximum Path Intersection Sum in a Grid

LeetCode 3939 - Count Non Adjacent Subsets in a Rooted Tree

LeetCode 3936 - Minimum Swaps to Move Zeros to End

LeetCode 3934 - Smallest Unique Subarray

LeetCode 3932 - Count K-th Roots in a Range

LeetCode 3931 - Check Adjacent Digit Differences

LeetCode 3928 - Minimum Cost to Buy Apples II

LeetCode 3927 - Minimize Array Sum Using Divisible Replacements

LeetCode 3925 - Concatenate Array With Reverse

LeetCode 3904 - Smallest Stable Index II

LeetCode 3923 - Minimum Generations to Target Point

LeetCode 3921 - Score Validator

LeetCode 3920 - Maximize Fixed Points After Deletions

LeetCode 3919 - Minimum Cost to Move Between Indices

LeetCode 3918 - Sum of Primes Between Number and Its Reverse

LeetCode 3917 - Count Indices With Opposite Parity

LeetCode 3914 - Minimum Operations to Make Array Non Decreasing

LeetCode 3915 - Maximum Sum of Alternating Subsequence With Distance at Least K

LeetCode 3913 - Sort Vowels by Frequency

LeetCode 3912 - Valid Elements in an Array

LeetCode 3911 - K-th Smallest Remaining Even Integer in Subarray Queries

LeetCode 3909 - Compare Sums of Bitonic Parts

LeetCode 3910 - Count Connected Subgraphs with Even Node Sum

LeetCode 3908 - Valid Digit Number

LeetCode 3906 - Count Good Integers on a Grid Path

LeetCode 3905 - Multi Source Flood Fill

LeetCode 3901 - Good Subsequence Queries

LeetCode 3903 - Smallest Stable Index I

LeetCode 3900 - Longest Balanced Substring After One Swap

LeetCode 3898 - Find the Degree of Each Vertex

LeetCode 3897 - Maximum Value of Concatenated Binary Segments

LeetCode 3895 - Count Digit Appearances

LeetCode 3894 - Traffic Signal Color

LeetCode 3896 - Minimum Operations to Transform Array into Alternating Prime

LeetCode 3892 - Minimum Operations to Achieve At Least K Peaks

LeetCode 3887 - Incremental Even-Weighted Cycle Queries

LeetCode 3886 - Sum of Sortable Integers

LeetCode 3849 - Maximum Bitwise XOR After Rearrangement

LeetCode 3874 - Valid Subarrays With Exactly One Peak

LeetCode 3861 - Minimum Capacity Box

LeetCode 3859 - Count Subarrays With K Distinct Integers

LeetCode 3824 - Minimum K to Reduce Array Within Limit

LeetCode 3820 - Pythagorean Distance Nodes in a Tree

LeetCode 3831 - Median of a Binary Search Tree Level

LeetCode 3810 - Minimum Operations to Reach Target Array

LeetCode 3814 - Maximum Capacity Within Budget

LeetCode 3809 - Best Reachable Tower

LeetCode 3797 - Count Routes to Climb a Rectangular Grid

LeetCode 3800 - Minimum Cost to Make Two Binary Strings Equal

LeetCode 3796 - Find Maximum Value in a Constrained Sequence

LeetCode 3798 - Largest Even Number