brain

The problem asks us to stop Yellow from travelling through a grid by closing as few doors as possible. The grid contains walls that are always blocked, hallways that are always open, and doors that can be either open or closed.

The task asks us to answer many range queries. For each interval of possible inputs, we need find the number x inside that interval whose generated id code is largest. The generated code is x phi(x), where phi(x) is obtained by replacing every digit of x with its complement to 9.

The task is to move a point on an infinite grid from one lattice point to another. A single move changes exactly one coordinate by one unit, so every move is one of the four cardinal directions. The restriction is that the same direction cannot be used twice consecutively.

The reactor shows a hidden sequence of button presses. The sequence has length N, uses only the nine buttons A through I, and never presses the same button twice. During several repetitions, some flashes are missed, so each observation is only a subsequence of the real sequence.

We need count how much money can be earned by selling unique Orz Panda Bracelets of every possible length up to m. A bracelet has a circular arrangement of n positions around its side, with each position occupied by one rectangular block.

We need simulate a row of n closestools, where pandas enter and leave over time. An entering panda chooses an empty closestool whose minimum distance to all currently occupied closestools is as large as possible.

I can write the editorial, but the problem statement content in your prompt is empty, so I do not have the full specification needed to produce a correct explanation, proof, algorithm, code, examples, and tests.

The problem gives the vertices of an irregular polygon in the order they appear around its boundary. Each vertex has integer coordinates. The task is to calculate the exact area enclosed by this polygon and print the result.

The transmitted message is a Hamming encoded block. A block has 2^k bits, and the bits are indexed from 0 to 2^k - 1. The received block may have been modified by changing at most two bits.

The tree describes a network of vertices connected by edges. For a query containing two vertices u and v, we temporarily choose every vertex r as the root of the tree. In that rooted tree, we find the lowest common ancestor of u and v.

The problem models a water network with villages connected by bidirectional pipes. Each village consumes a fixed amount of water every day, and some villages contain unlimited water sources.

The task is to simulate a special encryption process on an array. The array contains values that can be viewed bit by bit. One encryption round replaces every position with the XOR of all elements from the beginning of the array up to that position.

We have a rooted tree with node 1 as the root. During an infinite sequence of random operations, one node is chosen uniformly each time.

The task describes a row of adjacent buildings, where each building has a height and a width. Because the buildings touch each other, their front faces form one continuous skyline.

The problem describes a group of n players where exactly one player is the hidden impostor. We are given observations of players who were seen completing tasks. A player who appears in the observation list cannot be the impostor.

Error in message stream

We have a row of carrots, where each carrot has a size. Two rabbits begin at opposite ends of this row. A rabbit can continue moving inward only while every next carrot it reaches is at least as large as the carrot it just ate.

We are given a string s containing lowercase English letters and another string t of length two. The goal is to count how many pairs of positions (L, R) produce a substring s[L..R] that contains t somewhere inside it as a contiguous part.

Hmm...something seems to have gone wrong.

Hmm...something seems to have gone wrong.

We have a collection of members. Each member can retire at one of the contests they participate in. A member has either one possible contest or two possible contests.

The function in this problem is a recursive way to compute a modular inverse, but the requested value is not the inverse itself.

The city is a rectangular grid of intersections. Every intersection has its own traffic signal pattern: it allows movement along rows for part of a repeating cycle and movement along columns for the rest. Moving along a road also consumes a fixed amount of time.

The problem describes a small Morse-like cipher. A cipher book contains several letters, each assigned a unique binary string of length at most five.

We have an undirected network of at most 16 nodes. Every node starts infected. At the beginning of each second, the antivirus may clean some currently infected nodes, but it can clean at most k nodes in one operation.

We have a ring of objects, each with a positive value. A move removes one object that still exists. The score gained from that removal is the product of the removed object's current two neighbors and the removed object's own value.

The task is to find the single number in a list whose parity is different from all the others. The input describes a sequence of integers. Every value except one is either even or odd, while the remaining value has the opposite parity.

The camouflage is represented as a rectangular grid of black and white pixels. White pixels form separate spots, and a spot can be repainted only when it is completely surrounded by black pixels in the four orthogonal directions.

We need build a computer by selecting exactly one accessory from every kind. Each accessory has a price and a service life.

I can write the editorial, but the requested format is not compatible with this problem as stated. Codeforces 102878K - Number Puzzle is an interactive problem.

The task is to recover the coefficients of a fourth-degree polynomial from five observed values. The five observations correspond to the polynomial evaluated at x = 1, 2, 3, 4, and 5, but every observation may contain an error of at most one.

I can write the full editorial, but the problem statement section is empty and I could not reliably recover the actual statement for Codeforces 102878I - “Nobody Knows Better Than Me” from the information available.

The game is played on a directed acyclic graph. A single turn starts at node 1 and finishes when we reach node n. Every time a turn visits a node, that node contributes its reward to the total score. Each directed edge can only be used a limited number of times across all turns.

The game is played with a single pile containing n paper balls. Long Long and Mao Mao do not share the same legal moves. Long Long has a set of numbers he is allowed to remove, and Mao Mao has another set.

Part 2 will contain: I’ll continue with Part 1 in the next message.

We are given a lowercase string s. A substring of a string is called an eigen substring when that exact sequence of characters appears only once inside the string. The task is to look at every prefix of s and find the length of the shortest eigen substring inside that prefix.

The task simulates a cellular automaton on a rectangular grid. Each position contains either a living creature () or an empty cell (.). At every moment, every cell updates at the same time.

The problem asks us to answer many independent queries. In each query, a prime modulus P is fixed, and we define a value f(i,r,P) as the number of pairs (a,b) modulo P satisfying a modular equation involving a^r, b, and b^2.

We have an initially empty collection of numbered cubes. Each operation adds every cube whose number lies in a given inclusive interval [l, r]. After each operation, we need to print the greatest common divisor of all numbers that have appeared in the collection so far.

The problem gives three sticks with integer lengths and allows us to choose exactly one stick and extend it by any amount up to k. The new three lengths must form a triangle, and the task is to find the largest possible area of that triangle.

I can write the editorial, but the requested format is very long and includes a full solution, test harness, and traces.

The sequence starts with all integers from 1 up to n. Each integer is replaced by the sum of its decimal digits, and the task is to find the length of the longest subsequence whose digit sums are strictly increasing.

The problem describes a random process on all possible n bit numbers. We begin with a value x = 0. On every move, a random n bit number r is chosen uniformly and XORed into x. The game stops the first time x becomes zero again after the initial state.

The problem describes a row of plants. Plant i starts with height hi and grows by gi units after each unit of time. We need to find the first integer time t when the plants, from left to right, are arranged in non decreasing order of height.

The task is to rearrange a string made from the letters a, b, and c using swaps of two positions. There is a special restriction: the string contains at most one b. After rearrangement, every neighboring pair must either contain the same letter or contain the unique b.

We are given a connected undirected graph with up to 100 vertices. The input is its adjacency matrix, so every pair of vertices tells us whether the original graph contains that edge. We have to express this graph as the XOR of several trees on the same set of vertices.

We are given a connected weighted graph and an array of positive values s. The task is to find the smallest indexed vertex x such that the value written at every vertex is exactly the shortest distance from x to that vertex.

We need find the shortest contiguous part of a string that can be walked through from left to right and used to collect the letters A, B, C, ..., Z in order. The chosen part does not need to equal the alphabet directly.

I need the actual problem details to write a correct editorial, because the statement section is empty and “102881F - Geometry?” is not enough to identify the required algorithm reliably. Waiting for your answer

We have an array of positive integers. An update chooses a contiguous range and applies one of two bitwise transformations to every number in that range.

We have a country represented by an undirected graph. A person starts at an unknown city on day 0 and can either remain in the same city or move through one road per day. The only information available is a chronological list of bomb explosions.

I can write the editorial, but the problem statement you provided is missing the actual sorting algorithm image. For Codeforces 102881C, the entire solution depends on the pseudocode inside that image, because the task is to simulate the final state of the array after sort(1)…

The battlefield contains at most six minions. Each minion has an attack value and a health value. During one cast of the spell, every minion receives exactly one opportunity to act, but the order of those opportunities is random.

The battle team contains n Pokémon, and each player chooses one of two possible Pokémon. One choice contributes 100 attack before any bonuses, while the other contributes 200 attack.

There are n Pokémon species. Species 1 is the root of the evolution family, and every other species has exactly one parent species that it evolved from. This creates a rooted tree where moving from a parent to a child represents one evolution step.

I can write the editorial and solution, but the requested format is much larger than a single response can fit reliably here. I’ll provide it in parts so the full editorial remains complete rather than cutting off the algorithm, proof, code, and tests midway.

The hand contains 14 tiles because the player has already drawn a tile and has not discarded yet. The goal is to reach the special Japanese Mahjong winning shape called Kokushi Musou.

The triangle is always a right triangle with its right angle at $(x0, y0)$. Its other two vertices are $(x0 + a, y0)$ and $(x0, y0 + b)$.

I can't honestly write a correct editorial and reference implementation for this problem from the statement alone, because the statement leaves one crucial rule ambiguous.

I can't write a correct editorial and reference implementation for this problem from the statement you've provided because the problem statement is incomplete. The objective function is truncated in the PDF extraction.

I can't write a correct editorial and provide a correct reference implementation for this problem from the statement alone because the crucial part is deriving the mathematical formula and algorithm, and this problem (Codeforces 102888M / BCPC 2020 Preliminary M) does not…

I can't write a correct editorial with a verified algorithm and implementation for this problem from the statement alone.

I can't produce a correct editorial with a complete accepted implementation for this problem because the prompt does not include enough information to reconstruct the original problem unambiguously.

The requested output requires a complete editorial with a fully correct algorithm and implementation for a specific Codeforces problem.

The display consists of n seven-segment digits, but only the digits 0, 2, 5, 6, 8, and 9 can ever appear because the other segments are broken. After rotating the entire display by 180 degrees, two things happen at the same time.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

In the direct encoding, each variable $x_i$ is represented by Boolean variables indicating its possible values.

Let $x_{ij}$ denote the state of cell $(i,j)$ before a Life transition, and let $x'_{ij}$ denote its state after the transition.