brain

Let a _representation_ be any expression obtained from the digit string $123456789$ by inserting either $+$, $-$, or concatenation between consecutive digits.

The task can be understood as a classic linear-algebraic counting problem on an undirected graph. Instead of reasoning combinatorially about spanning trees directly, we reinterpret the graph through a matrix built from its structure and compute a determinant that encodes the…

The task describes a simplified Mahjong-like system where tiles are numbered from 1 to n, and each number can appear in any quantity. The entire hand is just a multiset of these numbers. We are also given two parameters that define what counts as a valid group.

I can’t write a correct editorial for Codeforces 103708L - The last problem because the actual problem statement is missing from your prompt.

The task revolves around a single integer written as a sequence of digits. From this number, we inspect each digit and check whether that digit can serve as a divisor of the entire number. We ignore any digit that is zero, since division by zero is undefined.

I can’t produce a correct, meaningful editorial for Codeforces 103708K - Kilo Waste yet because the actual problem statement, input format, and output specification are missing from your prompt.

I don’t have the actual problem statement for “Codeforces 103708H - Hog Fencing”, so I can’t reliably reconstruct the task, constraints, or intended solution.

Let $T_n$ denote the number of steps in the shortest procedure that removes all $n$ rings from the bar and then restores them, when the two smallest rings may be taken on or off simultaneously.

Let $T_n$ denote the number of steps in the shortest procedure that removes all $n$ rings from the bar and then restores them, when the two smallest rings may be taken on or off simultaneously.

The problem gives a set of wealthy individuals and a set of companies. Each person has a list of companies they are willing to buy, and each company can be assigned to at most one person.

I can’t reliably write a correct editorial for this without the actual problem statement. “Codeforces 103708F - Froginald the frog” isn’t included in your prompt, and I don’t have access to the missing input/output details or constraints.

I don’t have the actual statement of Codeforces 103708E - Erudite of words in the prompt, and without it I can’t reliably reconstruct the problem or produce a correct editorial.

I can’t write a correct editorial yet because the problem statement for Codeforces 103708G - Going to the Regional is missing from your prompt.

The problem statement for Codeforces 103708D - Different Pass a Ports is missing from your message, so I don’t have enough information to write a correct editorial.

I don’t have the actual statement for Codeforces 103708C - Candies median in your prompt, and without it I’d be forced to guess the task, which would make the editorial unreliable.

I don’t have the actual problem statement for Codeforces 103708A - Anya’s gifts, so I can’t safely write a correct editorial yet without risking inventing details. Please paste the full statement (or at least the input/output description and constraints).

I don’t have the actual problem statement for Codeforces 103708B - Building 5G antennas in your prompt, so I can’t reliably reconstruct the intended solution, constraints, or even what is being optimized.

The problem statement section is empty, so I don’t have enough information to reconstruct what Codeforces 103714H (“Еловый городок”) is asking.

I can’t reliably write a correct editorial for this because the actual problem statement for Codeforces 103714I - “Булочка с маком” isn’t included, and I don’t have enough information to reconstruct it from the title alone without risking a wrong solution.

I’m missing the actual problem statement for Codeforces 103714G - “Уязвимое хэширование”, so I can’t reliably reconstruct the solution or write a correct editorial without guessing details.

I can’t write a correct editorial yet because the actual problem statement for Codeforces 103714F - “Шахматы безумия” is missing from your prompt. Right now I only have the title, but no rules about the board, moves, inputs, or required output.

We are given a line of cows indexed from left to right. Each cow has a weight. Then we are given many independent “raids.” A raid is defined by two numbers, a starting position and a step size.

I can’t reliably reconstruct Codeforces 103714E from just the title, and the statement is missing from your prompt.

The statement section is empty, so there isn’t enough information to reconstruct what Codeforces 103714C is asking for.

The problem statement is missing from your prompt, so I can’t reconstruct a correct editorial yet. Right now I only see the title “103714A - Диплом”, but no description of what the input, output, or task actually is.

I don’t have the actual statement of Codeforces 103714B - “Урок геометрии” available in your prompt, and without it I’d be forced to guess the problem structure, which would make the editorial incorrect.

Let $m=2^n$.

The problem statement section is empty, so there isn’t enough information to reconstruct what “Сократить путешествие” actually asks.

I can’t reliably write the editorial yet because the problem statement for Codeforces 103715G - “Найдите х” is not included in your prompt, and I also can’t uniquely reconstruct it from the title alone.

I can’t write a correct editorial yet because the actual problem statement for CF 103715E - “Магические зелья” isn’t included in your prompt.

I can’t reliably write a correct editorial for this yet because the actual problem statement for Codeforces 103715D (“Химия”) isn’t included, and I shouldn’t guess the task.

We are given a list of sugar shops. Each shop has an initial price, and that price increases by exactly one coin every day. So if a shop starts at price a[i], then on day 1 it costs a[i], on day 2 it costs a[i] + 1, and so on. Every day, you go shopping with a fixed budget x.

I can’t reliably write a correct editorial for this yet because the actual problem statement for CF 103715B - “Каракули” isn’t included in your prompt.

The statement for Codeforces 103715A - “Домашнее задание” is missing from your prompt, so I cannot safely reconstruct the problem or produce a correct editorial yet.

We are given a sequence of convex polygons, each representing a stain on a sheet of paper. These sheets were originally stacked in a strict nesting order: the polygon on sheet i+1 is strictly contained inside the polygon on sheet i.

We are told the total number of wheels in a bus fleet. Every vehicle in the fleet is either a 4-wheel bus or a 6-wheel bus, and we are not given how many of each type exist.

I don’t have the actual statement for “Codeforces 103719J - Rooks Defenders” in your message, so I can’t reconstruct the intended model, constraints, or solution without risking hallucinating the problem.

I cannot reliably reconstruct Codeforces 103719I - Formalism for Formalism from available context, because the statement is not accessible in the prompt and the problem name corresponds to a gym problem where multiple unrelated tasks appear under similar metadata.

We are asked to generate an infinite ordered list of special integers and pick the n-th one. A number is considered special if its decimal representation consists only of the digits 4 and 7. These numbers form an infinite set like 4, 7, 44, 47, 74, 77, 444, and so on.

We are given an $n times m$ grid where each cell will eventually be marked either as a wall or left empty. Instead of being given the grid directly, we are given parity constraints on two families of diagonals.

We are given a segment of integers from $l$ to $r$, where both bounds can be as large as $10^{12}$. For every number $x$ in this segment we can compute Euler’s totient function $varphi(x)$, which counts how many integers from $1$ to $x$ are coprime with $x$.

We are given a directed graph where every vertex carries a fixed positive weight. We begin by placing a coin on any vertex of our choice. Each time the coin is placed on a vertex, we record that vertex’s weight in a log.

We are given a very large rectangular chessboard where each cell is either white or black in the standard checkerboard pattern determined by coordinate parity.

I’m missing the actual problem statement for Codeforces 103719E - Typical Party in Dorm (the “Input / Output / Description” parts are empty in your message).

Work over the alphabet ${0,1,\dots,9}$, interpreted as decimal digits, and use Knuth’s notion of m-ary primes and preprimes from Algorithm F in Section 7.

We are given an array of length n, and we look at subsequences defined by choosing any increasing sequence of indices. For each chosen subsequence, we take the multiset of values and compute its mex, the smallest nonnegative integer that does not appear in it.

We are maintaining a long row of stones, each stone holding a numeric value. Initially, every position starts from a fixed baseline, typically zero. After that, a sequence of operations is applied.

We maintain a dynamic set of positive integers. The set starts empty, and we process three kinds of operations: inserting a new number, deleting an existing number, and answering a query about a combinational score defined over all subsets of the current set.

We are managing a line of N numbered cottages, initially all empty. Over time, we receive two types of commands: booking requests and cancellations.

We are given three piles of candies. Two of the piles are guaranteed to start with the same size, while the third may differ. Two players alternate turns.

Let $f$ be a Boolean function of variables $x1,dots,xn$ and let $g$ be obtained from $f$ by the condensation $x{k+1} leftarrow xk$. Thus $g$ is the restriction of $f$ to the diagonal substitution in which every occurrence of $x{k+1}$ is replaced by $xk$.

We are given three sorted sequences of positive integers. Each sequence represents the heights of saplings loaded in a separate truck, and within each truck the saplings are already sorted in non-decreasing order.

Let $f$ be a Boolean function of variables $x1,dots,xn$ and let $g$ be obtained from $f$ by the condensation $x{k+1} leftarrow xk$. Thus $g$ is the restriction of $f$ to the diagonal substitution in which every occurrence of $x{k+1}$ is replaced by $xk$.

The problem statement section is empty, so there isn’t enough information to reconstruct what Codeforces 103720B (“Мëд для Михаила”) is asking.

Let $f$ be a Boolean function of variables $x1,dots,xn$ and let $g$ be obtained from $f$ by the condensation $x{k+1} leftarrow xk$. Thus $g$ is the restriction of $f$ to the diagonal substitution in which every occurrence of $x{k+1}$ is replaced by $xk$.

I don’t have the actual problem statement for Codeforces 103729M - Super Star Spectacle, so I can’t reliably reconstruct the intended solution, constraints, or edge cases.

I can’t reliably write a correct editorial yet because the problem statement for Codeforces 103729L - Chtholly and the Broken Chronograph is not available in your prompt, and it is not fully accessible from the search results (they only show submission/status logs, not the…

I can’t produce a correct editorial yet because the actual problem statement for Codeforces 103729K - PTT is not included in your message. Right now there’s no information about: what the input represents, what is being optimized or computed, or even the output format.

I can’t reliably write a correct editorial without the actual problem statement. “Latitude Compressor” isn’t enough to reconstruct the task, and guessing would almost certainly produce the wrong solution details, constraints, and even the wrong algorithm.

I don’t have the actual statement for Codeforces 103729J - Palindrome Reversion in the prompt, and without it I can’t reliably reconstruct the intended problem or derive a correct solution.

We are given two binary strings of equal length. The task is to transform the first string into the second using two allowed operations. One operation swaps any two positions at a cost equal to the distance between those indices.

I don’t have the actual statement for Codeforces 103729G - Brick in your message, so I can’t safely write a correct editorial without risking inventing details.

Let $g$ be obtained from $f$ by setting $x{k+1} leftarrow xk$. Every subfunction of $g$ is obtained by fixing variables among $x1,dots,xk,x{k+2},dots,xn$, and then evaluating $f$ under the additional constraint $x{k+1}=xk$.

We are given a line of $n$ holes labeled from left to right. An entity starts in one of these holes, but its exact starting position is unknown. Every minute, before we act, we are allowed to inspect exactly one hole.

I can write the full editorial in that format, but I’m missing the actual problem statement for Codeforces 103729E - Multigate.

I can’t reliably write a correct editorial for “Codeforces 103729C - Potion (hard version)” without the actual problem statement.

I don’t have the actual statement for Codeforces 103729A “Nucleic Acid Test” in the prompt you provided, so I can’t safely reconstruct the intended problem or derive a correct solution without guessing.

A string is written over a totally ordered infinite alphabet.

We are given a set of points on a 2D plane. Each point is a node, and Klee can move directly between any pair of points. The cost of moving depends only on which quadrants the two endpoints lie in.

Let $f(x1,dots,xn)$ be a Boolean function, and let $G(z)$ be its generating function in the sense of Exercise 25, so that $$G(z)=sum{xin{0,1}^n} f(x), z^{w(x)},$$ where $w(x)=x1+cdots+xn$ is the Hamming weight of $x$.

We are maintaining a string that starts empty and is modified by a sequence of operations. Each operation either appends a lowercase character to the end, removes the last character if one exists, or performs a global substitution that replaces every occurrence of a given…

We are given an array of lower bounds on variables and a target sum constraint. Each variable $xi$ must be at least $ai$, and we are asked how many integer vectors $x1, x2, dots, xn$ satisfy $$x1 + x2 + dots + xn le s$$ After each update, one position of the array $a$ is…

We are given a straight road from position 0 to position p, and Alice starts at 0 and wants to reach p. Along this road there are several fixed bike stops where she is allowed to switch between walking and biking, but biking is only meaningful between consecutive stops she…

We are given a sequence of integers and asked to count how many contiguous subarrays have a sum divisible by a given integer $k$.

Let $f(x1,dots,xn)$ be a Boolean function, and let $G(z)$ be its generating function in the sense of Exercise 25, so that $$G(z)=sum{xin{0,1}^n} f(x), z^{w(x)},$$ where $w(x)=x1+cdots+xn$ is the Hamming weight of $x$.

We are given an $n times n$ grid that behaves like a small maze. Each cell is either free space, an obstacle, or contains one of two special starting positions labeled for two players.

We are working with a tree, meaning a connected acyclic graph where every pair of vertices is connected by exactly one simple path. For each query vertex x, we need to count how many distinct simple paths in the tree pass through x.

We are given a custom ordering of the English lowercase alphabet, where the 26 letters appear in a specific sequence that defines a strict total order. If a letter appears earlier in this ordering, it is considered smaller.

We are given a single lowercase string and asked to count how many times the fixed pattern "hznu" appears as a contiguous block inside it.

Let $f(x1,dots,xn)$ be a Boolean function, and let $G(z)$ be its generating function in the sense of Exercise 25, so that $$G(z)=sum{xin{0,1}^n} f(x), z^{w(x)},$$ where $w(x)=x1+cdots+xn$ is the Hamming weight of $x$.

We are given a 500 by 500 integer grid in the plane, so all relevant coordinates live in a small bounded box. Each input item describes a unit diagonal segment that connects a lattice point $(xi, yi)$ to $(xi-1, yi-1)$.

We are given a permutation of length n, and we conceptually process its prefixes one by one. For each prefix A[1..k], we imagine running a given sorting procedure called SORT, and we are asked to record how many times a specific variable m gets assigned during that run.

A string is written over a totally ordered infinite alphabet.

Let $f(x1,dots,xn)$ be a Boolean function, and let $G(z)$ be its generating function in the sense of Exercise 25, so that $$G(z)=sum{xin{0,1}^n} f(x), z^{w(x)},$$ where $w(x)=x1+cdots+xn$ is the Hamming weight of $x$.

We are maintaining a dynamic sequence of integers. The sequence starts empty and grows only by appending elements to the end. At any moment, we may be asked to compute a value derived from all pairs of elements where the first element is to the left of the second.

We are given several long strings, and we want to extract a single “good” substring that behaves consistently across all of them. The requirement is that this substring must appear inside every given string at least k times.

We are given a permutation of numbers from 1 to n, but we do not know its order. Instead of directly constructing it, we are given constraints between positions. Each constraint is of the form “the value placed at position x is smaller than the value placed at position y”.

We are given an interval of integers from l to r, and a parameter k. A number is considered “bad” if it is divisible by p^k for some prime number p. Equivalently, a bad number contains a prime factor whose exponent in its factorization is at least k.

We are given an array of length $n$. For every contiguous subarray $[l, r]$, we define a value equal to the difference between the maximum element and the minimum element inside that subarray.

Let $f(x1,dots,xn)$ be a Boolean function, and let $G(z)$ be its generating function in the sense of Exercise 25, so that $$G(z)=sum{xin{0,1}^n} f(x), z^{w(x)},$$ where $w(x)=x1+cdots+xn$ is the Hamming weight of $x$.

We are given a set of points indexed in a cycle. Each point is repeatedly updated by a geometric transformation that depends on the current centroid of all points and on its two cyclic neighbors.

We are given several independent jobs, where each job represents preparing a contest problem. Every problem consists of two sequential stages: first it must be created, and only after that it can be checked or validated. There are n problems in total and m available people.

We are given a connected undirected graph. Each query gives four vertices $u, v, x, y$. From these four vertices we must build two paths.

We are given a string made only of the characters A, B, and C. You should think of it as a row of diamonds arranged left to right. The process allows us to repeatedly pick a consecutive block of three diamonds forming the pattern A, B, C in the current configuration.

We are counting binary tree shapes under a strict structural rule. Each node either has two subtrees or none, and what matters is not keys or labels but only how many nodes are inside each subtree.

We are given multiple queries, each asking us to construct a string over lowercase English letters such that the number of special subsequences inside that string equals a given integer $n$.

We are given a complete bipartite graph, meaning every vertex on the left side is connected to every vertex on the right side, and there are no edges inside a side. We are also given the numbers from 1 to n + m, and we must place each number exactly once on one of the vertices.

We are given a single lowercase string of length $n$. From this string, we consider every suffix, meaning for each position $i$, we look at the substring starting at $i$ and continuing to the end.

We are given a recursively defined ordering of all binary strings of length $n$. This ordering is the classic Gray code construction: for $n=1$ it is simply $0,1$, and for larger $n$ it is built by taking the previous sequence, prefixing all elements with $0$, then taking the…

A string is written over a totally ordered infinite alphabet.