LeetCode 957: Prison Cells After N Days
A clear explanation of simulating prison cell transitions efficiently using cycle detection.
Tag
Simulation
80 notes
LeetCode 844: Backspace String Compare
A clear explanation of the Backspace String Compare problem using stack simulation and an O(1) space two-pointer scan.
LeetCode 840: Magic Squares In Grid
A clear explanation of the Magic Squares In Grid problem using fixed-size subgrid validation.
LeetCode 833: Find And Replace in String
A clear explanation of the Find And Replace in String problem using simultaneous replacement, source matching, and a replacement map.
LeetCode 832: Flipping an Image
A clear explanation of the Flipping an Image problem using row reversal, bit inversion, and an in-place two-pointer method.
LeetCode 831: Masking Personal Information
A clear explanation of the Masking Personal Information problem using string parsing and format-specific masking rules.
LeetCode 900: RLE Iterator
A clear explanation of designing an iterator over a run-length encoded sequence without expanding it.
LeetCode 885: Spiral Matrix III
A clear explanation of generating grid coordinates in an outward clockwise spiral using simulation.
LeetCode 883: Projection Area of 3D Shapes
A clear explanation of computing the projection areas of stacked cubes from top, front, and side views.
LeetCode 622: Design Circular Queue
A clear explanation of Design Circular Queue using a fixed array, a front pointer, and a size counter.
LeetCode 999: Available Captures for Rook
A clear explanation of counting how many pawns a rook can capture by scanning four directions on a chessboard.
LeetCode 989: Add to Array-Form of Integer
A clear explanation of adding an integer to an array-form number using digit-by-digit simulation.
LeetCode 985: Sum of Even Numbers After Queries
A clear explanation of maintaining the sum of even numbers after each array update.
LeetCode 874: Walking Robot Simulation
A clear explanation of simulating robot movement on an infinite grid using direction vectors and obstacle lookup.
LeetCode 867: Transpose Matrix
A clear explanation of transposing a matrix by swapping row and column indices.
LeetCode 860: Lemonade Change
A clear explanation of Lemonade Change using greedy simulation and bill counting.
LeetCode 855: Exam Room
A clear explanation of simulating an exam room by maintaining occupied seats in sorted order.
LeetCode 950: Reveal Cards In Increasing Order
A clear explanation of solving Reveal Cards In Increasing Order using sorting and queue simulation over indices.
LeetCode 946: Validate Stack Sequences
A clear explanation of solving Validate Stack Sequences by simulating stack push and pop operations.
LeetCode 941: Valid Mountain Array
A clear explanation of solving Valid Mountain Array by walking up the increasing slope and then down the decreasing slope.
LeetCode 929: Unique Email Addresses
A clear explanation of solving Unique Email Addresses using string normalization and a hash set.
LeetCode 928: Minimize Malware Spread II
A clear explanation of solving Minimize Malware Spread II by removing each infected node and simulating the final malware spread.
LeetCode 824: Goat Latin
A string simulation solution for converting each word in a sentence into Goat Latin.
LeetCode 806: Number of Lines To Write String
A simple simulation solution for counting how many 100-pixel lines are needed to write a string.
LeetCode 799: Champagne Tower
A clear explanation of simulating overflow in a champagne glass pyramid using dynamic programming.
LeetCode 794: Valid Tic-Tac-Toe State
A clear explanation of validating whether a Tic-Tac-Toe board can occur in a legal game.
LeetCode 758: Bold Words in String
A clear explanation of marking matching substrings and merging overlapping bold ranges.
LeetCode 755: Pour Water
A clear explanation of simulating water droplets over an elevation map by checking left first, then right.
LeetCode 725: Split Linked List in Parts
A clear explanation of splitting a linked list into k consecutive parts with sizes as equal as possible.
LeetCode 723: Candy Crush
A clear explanation of restoring a Candy Crush board to a stable state using repeated marking, crushing, and gravity simulation.
LeetCode 722: Remove Comments
A clear explanation of removing line comments and block comments from source code using a state machine.
LeetCode 749: Contain Virus
Simulate virus containment by repeatedly quarantining the most dangerous infected region and spreading the remaining regions.
LeetCode 735: Asteroid Collision
Simulate asteroid collisions using a stack that keeps the surviving asteroids in order.
LeetCode 728: Self Dividing Numbers
Check each number in a range by extracting its digits and testing whether every digit divides the original number.
LeetCode 699: Falling Squares
Simulate falling squares on a number line and track the maximum stack height after each placement.
LeetCode 682: Baseball Game
Simulate a baseball scoring system using a stack to process operations and compute the final score.
LeetCode 681: Next Closest Time
Find the next valid 24-hour time using only the digits from the current time.
LeetCode 661: Image Smoother
A clear explanation of averaging neighboring pixels in a matrix using direct simulation.
LeetCode 657: Robot Return to Origin
A clear explanation of determining whether a robot returns to the origin after executing movement instructions.
LeetCode 649: Dota2 Senate
A queue-based simulation for predicting which party wins after senators ban opponents in turn order.
LeetCode 640: Solve the Equation
A string parsing solution for reducing a linear equation into coefficient and constant terms.
LeetCode 636: Exclusive Time of Functions
A stack-based solution for computing exclusive execution time from nested start and end logs.
LeetCode 43: Multiply Strings
A clear explanation of Multiply Strings using grade-school multiplication with digit arrays.
LeetCode 573: Squirrel Simulation
A clear explanation of Squirrel Simulation using Manhattan distance and the special first trip.
LeetCode 566: Reshape the Matrix
A clear explanation of Reshape the Matrix using index mapping from the original matrix to the reshaped matrix.
LeetCode 551: Student Attendance Record I
A clear explanation of Student Attendance Record I using simple string checks and a one-pass counter solution.
LeetCode 544: Output Contest Matches
A clear explanation of building the final tournament bracket by repeatedly pairing strongest and weakest teams.
LeetCode 541: Reverse String II
A clear explanation of reversing the first k characters in every 2k block of a string.
LeetCode 537: Complex Number Multiplication
A clear explanation of multiplying complex numbers represented as strings using algebraic expansion.
LeetCode 498: Diagonal Traverse
A clear explanation of returning matrix elements in diagonal zigzag order by grouping cells with the same row plus column index.
LeetCode 495: Teemo Attacking
A clear explanation of calculating total poisoned duration by merging overlapping attack intervals.
LeetCode 489: Robot Room Cleaner
A clear explanation of cleaning an unknown grid using DFS, relative coordinates, and physical backtracking.
LeetCode 485: Max Consecutive Ones
A clear explanation of finding the longest streak of 1s in a binary array with a single pass.
LeetCode 482: License Key Formatting
A clear explanation of reformatting a license key by removing dashes, uppercasing characters, and grouping from the right.
LeetCode 481: Magical String
A clear explanation of constructing the magical string by using the string itself as run-length instructions.
LeetCode 468: Validate IP Address
A clear explanation of validating IPv4 and IPv6 addresses by checking segment count, length, characters, range, and leading-zero rules.
LeetCode 466: Count The Repetitions
A clear explanation of counting how many repeated copies of one string can be obtained as a subsequence of another repeated string.
LeetCode 463: Island Perimeter
A clear explanation of counting the perimeter of an island in a grid by adding land-cell edges and subtracting shared edges.
LeetCode 434: Number of Segments in a String
Count the number of word segments in a string by detecting transitions from spaces to non-space characters.
LeetCode 422: Valid Word Square
A clear explanation of checking whether rows and columns read the same using direct index comparison.
LeetCode 418: Sentence Screen Fitting
A clear explanation of fitting a sentence onto a screen using cyclic string simulation and greedy row transitions.
LeetCode 415: Add Strings
A clear explanation of adding two non-negative integer strings using manual digit-by-digit simulation.
LeetCode 412: Fizz Buzz
A clear explanation of the Fizz Buzz problem using direct simulation and divisibility checks.
LeetCode 408: Valid Word Abbreviation
A clear explanation of validating a word abbreviation using two pointers and number parsing.
LeetCode 390: Elimination Game
A clear explanation of finding the last remaining number after alternating left-to-right and right-to-left eliminations.
LeetCode 311: Sparse Matrix Multiplication
A clear explanation of Sparse Matrix Multiplication using non-zero entries to avoid wasted work.
LeetCode 293: Flip Game
A simple string scanning solution for generating every possible next state after flipping one consecutive ++ pair into --.
LeetCode 289: Game of Life
An in-place matrix simulation for computing the next state of Conway's Game of Life using temporary encoded states.
LeetCode 258: Add Digits
A clear explanation of the Add Digits problem using repeated digit sums first, then the digital root formula.
LeetCode 163: Missing Ranges
A clear explanation of finding all missing ranges inside an inclusive interval by scanning sorted unique numbers.
LeetCode 158: Read N Characters Given read4 II - Call Multiple Times
A clear explanation of implementing read with read4 when read may be called multiple times.
LeetCode 157: Read N Characters Given Read4
A clear explanation of implementing read using the given read4 API and copying only the needed characters.
LeetCode 68: Text Justification
A clear guide to formatting text with greedy line packing and even space distribution.
LeetCode 67: Add Binary
A clear guide to adding two binary strings using two pointers and a carry.
LeetCode 59: Spiral Matrix II
A clear guide to generating an n x n matrix filled from 1 to n squared in spiral order.
LeetCode 54: Spiral Matrix
A clear guide to reading a matrix in spiral order using shrinking boundaries.
LeetCode 38: Count and Say
A clear explanation of generating the count-and-say sequence using run-length encoding.
LeetCode 8: String to Integer (atoi)
A detailed explanation of parsing a string into a 32-bit signed integer with whitespace, sign, digit reading, and clamping rules.
LeetCode 6: Zigzag Conversion
A detailed explanation of converting a string into a zigzag pattern using row simulation.
11.3 Universal Machines
Machines that simulate any other Turing machine, establishing the concept of programmable computation.