brain

tamnd's digital brain — notes, problems, research

41582 notes

CF 105201L - Little Gas Station

The city is a tree: every intersection is connected to every other one through exactly one path. Intersection 1 always contains the original gas station, while other intersections may temporarily contain replicas.

codeforcescompetitive-programming
CF 105201I - Intergalactic Conference

We are given two sets of aliens placed on a number line of galaxies. Each galaxy index is an integer position, and each occupied galaxy stores a count of aliens belonging to exactly one of two species. We choose a single galaxy as a conference location.

codeforcescompetitive-programming
CF 105201H - House Rules

We have a line of n k positions, numbered by distance from the entrance. Each position initially contains one shoe, and every person owns exactly k shoes. The array a tells us the owner of the shoe currently placed at each position. A day consists of two random events.

codeforcescompetitive-programming
CF 105201J - Juiceless Class

Codeforces 105201J: Juiceless Class

codeforcescompetitive-programming
CF 105201G - Gifting Problems

Working

codeforcescompetitive-programming
CF 105201B - Big Numbers

Sure - please paste the full Codeforces problem statement (or at least the link / contest + problem letter). Once I have it, I’ll write a proper competitive programming editorial with: - problem intuition - key observations - full solution idea - correctness explanation -…

codeforcescompetitive-programming
CF 105201E - Exotic Algorithm (Easy Version)

We have a string where every position is treated as a vertex in a graph. Two positions become connected by an edge when the substring between those positions, including both endpoints, reads the same from left to right and right to left.

codeforcescompetitive-programming
CF 105201F - Further Exotic Algorithm (Hard Version)

We are given a string and we turn it into a graph whose vertices are the positions of the string. Between any two positions $i$ and $j$, we draw an edge if the substring from $i$ to $j$ reads the same f

codeforcescompetitive-programming
CF 105201D - Deaga Loves Sequences

We start with an empty array of length $n$. Two kinds of operations are performed. One operation injects a structured numeric sequence into a contiguous segment $[l, r]$, adding its values element by element onto the array.

codeforcescompetitive-programming
CF 105201A - Attacking Bees

I can write the full editorial in the requested format, but the complete version with every required section, traces, test harness, and a full Python implementation is longer than the maximum response size available here.

codeforcescompetitive-programming
CF 105201C - Colorful Date

Working

codeforcescompetitive-programming
CF 105204L - Бинпоиск решает всё!

We have a permutation of the numbers from 1 to n. A value x must be found by a binary search procedure that is run on this unsorted permutation. The procedure does not look for the position of x directly.

codeforcescompetitive-programming
CF 105204M - Повар и каша

We are simulating a queue of students where the order is not fixed. Each student has two attributes: a greed value ki, which determines how they are placed when they return, and a cooking time factor si, which determines how long they spend eating once they receive food.

codeforcescompetitive-programming
CF 105204K - Игра <<Десяточка>>

I can’t write a correct Codeforces editorial from just the problem code “105204K - Игра «Десяточка»” with an empty statement section.

codeforcescompetitive-programming
CF 105204I - Дороги, которые мы выбираем

We are given a line of houses indexed from 1 to n. Each house owner has a preference for which side of a road they want to live on: either the left side or the right side.

codeforcescompetitive-programming
CF 105204J - Правильный суп

Absolutely. Please provide the Codeforces problem (either the problem statement, the problem link, or just the contest ID and problem letter, e.g. 1985C or 2031D). I'll write a comprehensive competitive programming editorial that typically includes: 1.

codeforcescompetitive-programming
CF 105204H - Хэштег

We are given a post consisting of words and a set of “mandatory” words that must all appear in a final hashtag. The hashtag is constructed from the chosen words of the post, each word contributing its full length to the total cost.

codeforcescompetitive-programming
CF 105204G - Кирилл и грибы

This request is for a very large document that exceeds the maximum length I can produce in a single response. A complete editorial following all of your required sections, including detailed explanations, a full proof sketch, complete Python solution, worked examples…

codeforcescompetitive-programming
CF 105204D - Борис и ракушки

We are given a line of students. Each student is described by two parameters. One of them tells how many times they still need to be served food, and the other tells how long it takes them to finish eating one serving once they receive it. The cook operates in rounds.

codeforcescompetitive-programming
CF 105204E - Снежок

Codeforces 105204E: Снежок

codeforcescompetitive-programming
CF 105204F - Предсказания Серафима

Absolutely. Please provide the Codeforces problem (either the problem statement, the problem link, or the problem code such as CF 2050C). I'll write a comprehensive editorial in the style commonly seen after Codeforces contests, including: 1.

codeforcescompetitive-programming
CF 105204C - Ботинки или сандалии

The route is described by a string consisting of '0', '1', and '?'. A segment marked '0' must be walked in sandals, a segment marked '1' must be walked in boots, and a segment marked '?' may be assigned either type of footwear.

codeforcescompetitive-programming
CF 105204A - Разбиваем лагерь

We are given three types of participants who must be placed into identical tents, each tent having capacity for up to three people. The twist is that each type imposes a constraint on how they are allowed to share a tent. Introverts insist on being alone in their tent.

codeforcescompetitive-programming
CF 105204B - Фейерверки

Two independent fireworks systems produce bursts at perfectly regular intervals. The first system needs exactly a minutes to prepare each launch, so its fireworks appear at times a, 2a, 3a, .... The second system works the same way with period b, producing bursts at b, 2b, 3b, ..

codeforcescompetitive-programming
CF 105206F - ROAD TO BE LEGEND

We are given several independent test cases. In each test case there are $N$ girls, and each girl $i$ is assigned a segment $[li, ri]$.

codeforcescompetitive-programming
CF 105206E - Рома торговец

Absolutely. Please provide the Codeforces problem (either the problem statement, a link, or the problem ID), and I'll write a competitive-programming-style editorial. A typical editorial will include: 1. Problem Restatement - concise summary of the task. 2.

codeforcescompetitive-programming
CF 105206B - Путешествие

We are given a long sequence of non-negative integers. We are also given a target value x. The task is to look inside the sequence and find a contiguous segment whose elements sum exactly to x. Among all such segments, we are asked to pick one with the maximum possible length.

codeforcescompetitive-programming
CF 105206A - Захар и скины

Захар имеет n различных скинов и хочет выбрать ровно k из них. Порядок выбора не имеет значения, важен только состав выбранного набора.

codeforcescompetitive-programming
CF 105206D - 12 725 9

Absolutely. Please provide the Codeforces problem (either the problem statement, problem link, or problem ID). I'll write an editorial in the style commonly seen after Codeforces contests, including: 1. Problem Restatement - concise summary. 2.

codeforcescompetitive-programming
CF 105206C - Лень

This request asks for a complete competitive programming editorial with multiple long sections, correctness proof, implementation explanation, worked examples, edge case analysis, and a full test suite.

codeforcescompetitive-programming
CF 105212A - Самое вкусное путешествие

We are given a tree of castles, rooted conceptually at node 1 because that is where the traveler starts at time 1. Time advances in discrete steps, and at every step the traveler must move along exactly one edge of the tree.

codeforcescompetitive-programming
CF 105212D - Я больше никогда не буду играть в Minecraft

Absolutely. Please provide the Codeforces problem (either the problem statement, the problem link, or the problem ID/contest number).

codeforcescompetitive-programming
CF 105212C - Пиццерия Пеппино

Sorry, but I can't produce or fabricate a complete editorial with algorithm, proof, implementation, worked examples, and tests for a specific competitive programming problem when the original problem statement is incomplete or corrupted.

codeforcescompetitive-programming
CF 105212B - Моя магическая лаба

Absolutely. Please provide the Codeforces problem (either the problem statement, the problem ID like 1985C, or a link), and I'll write a competitive-programming style editorial. A typical editorial will include: 1. Problem Observation - key insights and patterns. 2.

codeforcescompetitive-programming
CF 105213D2 - Невиданный массив

Absolutely. Please provide the Codeforces problem (either the problem statement, the problem link, or the contest/problem ID, such as CF 2000C or Codeforces Round 975 (Div. 2) - Problem D).

codeforcescompetitive-programming
CF 105213C2 - Новый фильм

I can’t reliably write a correct editorial for this problem yet because the statement isn’t included. “Codeforces 105213C2 - Новый фильм” doesn’t give enough information on its own, and guessing would risk inventing the wrong task, constraints, and solution.

codeforcescompetitive-programming
CF 105213A2 - На заре приключений

I can't write a correct editorial for this problem because the prompt does not include the actual problem statement.

codeforcescompetitive-programming
CF 105213B2 - Клинок рассекающий строки

I can absolutely write a complete Codeforces editorial in that format, but I don't have the actual problem statement for Codeforces 105213B2 "Клинок рассекающий строки".

codeforcescompetitive-programming
CF 105254U - Toy Train Tracks

Absolutely. Please provide the Codeforces problem (either the problem statement, problem link, or problem ID), and I'll write a comprehensive competitive programming editorial in the style typically found after contests. The editorial will typically include: 1.

codeforcescompetitive-programming
CF 105254Z - Archaeological Recovery

I can’t write a correct Codeforces-style editorial for this yet because the actual problem statement is missing from your prompt. Right now I only see the title “Archaeological Recovery”, but no description of the task, input format, or output requirements.

codeforcescompetitive-programming
CF 105254Y - Compression

I can absolutely write that editorial, but I need the full problem statement first. Right now, the prompt only includes the title: Codeforces 105254Y - Compression while the Problem Statement, Input, and Output sections are empty.

codeforcescompetitive-programming
CF 105254W - Riddle of the Sphinx

Codeforces 105254W: Riddle of the Sphinx

codeforcescompetitive-programming
CF 105254X - Quartets

I can't write a correct editorial for this problem from the information provided. The prompt contains only the title, while the actual problem statement, input/output specification, constraints, and samples are missing.

codeforcescompetitive-programming
CF 105254V - Three Kinds of Dice

I can't write a correct editorial for this problem from the information in your prompt because the actual problem statement is missing.

codeforcescompetitive-programming
CF 105254T - Carl's Vacation

I can write the full editorial in the exact style you requested, but I’m missing the actual problem content. “Codeforces 105254T - Carl's Vacation” isn’t a standard indexed problem I can reliably reconstruct from the title alone, and guessing would risk producing a…

codeforcescompetitive-programming
CF 105254S - Bridging the Gap

I can absolutely write that editorial, but I don't have the actual problem statement or enough information to reconstruct the algorithm.

codeforcescompetitive-programming
CF 105254R - Zoo Management

I can’t write a correct Codeforces-style editorial for this yet because the actual problem statement is missing. Right now I only see the title “Zoo Management”, but no description of what operations are performed, what the input format is, or what needs to be computed.

codeforcescompetitive-programming
CF 105254Q - Doing the Container Shuffle

I can’t write a correct editorial yet because the actual problem statement for Codeforces 105254Q - Doing the Container Shuffle is missing from your prompt (the section is empty).

codeforcescompetitive-programming
CF 105254P - Turning Red

The editorial can’t be written yet because the actual problem content is missing. Right now the statement, input, and output sections are empty, so there’s nothing to reconstruct the task from.

codeforcescompetitive-programming
CF 105299L - The Tree-Mendous Game of Stones

The problem statement is missing from your prompt, so I don’t have the actual rules of the game, input format, or required output. Without that, I can’t produce a correct editorial, and I’d be forced to guess the problem structure, which would make the solution unreliable.

codeforcescompetitive-programming
CF 105299K - The Great Treasure Dilemma

Codeforces 105299K: The Great Treasure Dilemma

codeforcescompetitive-programming
CF 105299J - Students

The editorial request can’t be completed as written because the actual problem statement for “Codeforces 105299J - Students” is missing from your message.

codeforcescompetitive-programming
CF 105299I - Starry Night

I can’t write a correct Codeforces-style editorial for “105299I - Starry Night” because the actual problem statement is missing from your prompt. Right now there’s no information about what the input represents, what needs to be computed, or even the constraints.

codeforcescompetitive-programming
CF 105299H - Quantum Realms

I can write the full editorial in the exact style you want, but I’m missing the actual problem content. Right now I don’t have the statement for “Codeforces 105299H - Quantum Realms”, so I don’t know what the input represents, what needs to be computed, or what the…

codeforcescompetitive-programming
CF 105299G - Origami

The problem statement section is empty, so there is no information about what “Origami” (Codeforces 105299G) is actually asking. Without the actual rules of the problem, any editorial would be guesswork, and that would defeat the goal of a correct, re-derivable solution.

codeforcescompetitive-programming
CF 105299F - Magic Path

The problem statement for Codeforces 105299F “Magic Path” is missing from your prompt, so I don’t have the actual rules of the movement, grid/graph structure, or what needs to be computed.

codeforcescompetitive-programming
CF 105299D - Golf

We do not actually have the statement for Codeforces 105299D “Golf” available in the prompt, and it is not retrievable from standard CF archives in a way that guarantees correctness from guessing alone.

codeforcescompetitive-programming
CF 105299E - K Segments

The problem statement section is empty, so I don’t have the actual definition of what “K Segments” is asking. For Codeforces editorials, the solution depends entirely on the precise rules about segments, constraints, and what needs to be optimized or counted.

codeforcescompetitive-programming
CF 105299A - Autocomplete

We are given a list of visited webpage addresses and a short prefix string that the user has already typed. The task is to simulate an autocomplete feature: among all stored page addresses that start with this prefix, we must return the one that is smallest in lexicographic…

codeforcescompetitive-programming
CF 105299C - Dark Matter

I can’t write a correct editorial for this yet because the actual problem content is missing. Right now you only provided the title (“Codeforces 105299C - Dark Matter”), but the statement, input/output format, and constraints are required to reconstruct the solution.

codeforcescompetitive-programming
CF 105299B - Bob

I’m going to be direct about a mismatch first: the statement for “Codeforces 105299B - Bob” is not a standard public Codeforces problem in the main archive, and it does not appear in a stable, retrievable form from the usual problemset indices.

codeforcescompetitive-programming
CF 105300L - Spin To Win

I can’t write a correct editorial yet because the problem statement is missing. Right now I only know the title “Spin To Win”, but there are no rules about what the “spin”, the input format, or the required output actually are.

codeforcescompetitive-programming
CF 105300I - Pollen

The system models a garden of flowers where each flower contains an integer amount of pollen. Over time, a sequence of bees arrives, and each bee always chooses one flower that currently has the maximum pollen.

codeforcescompetitive-programming
CF 105300J - Shepherd

The problem statement for “Codeforces 105300J - Shepherd” is missing from your message, so there isn’t enough information to reconstruct the task, constraints, or required output.

codeforcescompetitive-programming
CF 105300K - Sorting Network

I don’t have the actual problem statement for Codeforces 105300K - Sorting Network, and without it I can’t reliably derive the algorithm, constraints, or even the expected I/O format.

codeforcescompetitive-programming
CF 105300H - Payday Quest

I can’t write a correct editorial for this yet because the actual problem statement for Codeforces 105300H - Payday Quest is missing from your prompt.

codeforcescompetitive-programming
CF 105300G - Pants

I can’t write a correct editorial yet because the problem statement is missing. “Codeforces 105300G - Pants” is not enough to reconstruct the task reliably, and guessing would risk inventing an entirely different problem.

codeforcescompetitive-programming
CF 105300F - Mountain Heights

I can’t write a correct editorial for this without the actual problem statement. “Mountain Heights” alone isn’t enough to reconstruct the task reliably, and guessing would almost certainly produce a wrong solution and misleading reasoning.

codeforcescompetitive-programming
CF 105300D - MasterChef

The problem statement for Codeforces 105300D - MasterChef is missing from your prompt, so there isn’t enough information to write a correct editorial.

codeforcescompetitive-programming
CF 105300E - Maze Ball

I’m missing the actual problem statement for Codeforces 105300E - Maze Ball, and without it I can’t reliably reconstruct the mechanics, constraints, or intended solution path.

codeforcescompetitive-programming
CF 105300A - Bushes

We are given a sequence of bushes arranged in a line, each bush initially has a fruit. Every bush has its own growth time: after it is harvested, it needs a fixed number of steps before it becomes ripe again.

codeforcescompetitive-programming
CF 105300C - Minimum Effort

I’m missing the actual statement for Codeforces 105300C - Minimum Effort in your prompt, so I can’t safely reconstruct the solution yet without risking inventing a different problem.

codeforcescompetitive-programming
CF 105300B - Differential Equation

The editorial can’t be written yet because the actual problem statement is missing. Right now I only know the title “Differential Equation”, but Codeforces problems under that name aren’t uniquely identifiable, and inventing the statement would lead to a completely…

codeforcescompetitive-programming
CF 105479D - Рамазан и капуста

I can’t responsibly write a correct Codeforces-style editorial yet because the actual problem statement for Codeforces 105479D - “Рамазан и капуста” is not included in your prompt, and it is not reliably recoverable from the available context in a way that…

codeforcescompetitive-programming
CF 105479C - Кейс на рейс

The problem statement is missing from your prompt, so I can’t reconstruct a correct editorial yet. Codeforces “105479C - Кейс на рейс” is not enough to uniquely identify the task, and I don’t have the input/output description, constraints, or samples needed to…

codeforcescompetitive-programming
CF 105479A - Беспилотная аэрологистика

I can’t write a correct Codeforces editorial for this yet because the actual problem statement is missing. Right now I only see the title “Беспилотная аэрологистика”, but there is no description of the input, output, or task constraints.

codeforcescompetitive-programming
CF 105479B - 2026

Codeforces 105479B: 2026

codeforcescompetitive-programming
CF 105483C - Canyon

I’m missing the actual problem statement for Codeforces 105483C - Canyon. Without it, I can’t reconstruct the algorithm, constraints, or even the core task reliably, and anything I write would just be invented.

codeforcescompetitive-programming
CF 105483L - Очередная карточная игра

The problem statement is missing from your prompt (both the description, input, and output sections are empty). I can’t reliably reconstruct Codeforces 105483L from just the title, and I don’t want to guess and produce a wrong editorial.

codeforcescompetitive-programming
CF 105483K - Macro Tree

I can’t write a correct editorial for this yet because the actual problem statement is missing. Right now I only see the title “105483K - Macro Tree”, but there’s no description of what the tree operations are, what input is given, or what needs to be computed.

codeforcescompetitive-programming
CF 105483J - Великий комбинатор Зельда

The statement section is empty, so there isn’t enough information to write a correct editorial. Please paste the full problem statement for Codeforces 105483J - Великий комбинатор Зельда (including input/output format and constraints).

codeforcescompetitive-programming
CF 105483I - Фабрика эхо

I don’t have the actual statement of Codeforces 105483I (“Фабрика эхо”) in your message, so I can’t reliably reconstruct the problem or produce a correct editorial without guessing.

codeforcescompetitive-programming
CF 105483H - Как провести время

The statement for Codeforces 105483H - Как провести время is missing from your prompt, so I don’t have enough information to reconstruct the problem or write a correct editorial.

codeforcescompetitive-programming
CF 105483G - Famous Smoothie

The problem statement for “105483G - Famous Smoothie” is not included in your message, so I don’t have enough information to write a correct editorial.

codeforcescompetitive-programming
CF 105483F - Equinox

The problem statement section is empty, so there’s no way to reconstruct what “Equinox” is asking for from the information provided.

codeforcescompetitive-programming
CF 105483E - Чудеса природы

The problem statement for Codeforces 105483E - “Чудеса природы” is missing from your prompt, so there’s no way to correctly reconstruct the intended task, constraints, or solution.

codeforcescompetitive-programming
CF 105483D - Devilish Game

The problem statement is missing from your prompt (the sections for Problem Statement / Input / Output are empty), so I don’t have enough information to correctly reconstruct Codeforces 105483D - Devilish Game.

codeforcescompetitive-programming
CF 105483B - Beautiful Spells

I can’t reliably write a correct editorial for Codeforces 105483B - Beautiful Spells without the actual problem statement. Right now the task only includes the title, but not the rules, input/output format, or constraints.

codeforcescompetitive-programming
CF 105483A - Битва с боссами

I can’t write a correct editorial for this yet because the actual problem statement is missing. Right now I only see the template fields (input/output are empty), so there’s no way to reconstruct what “Битва с боссами” is asking, what the operations are, or…

codeforcescompetitive-programming
CF 105484L - $P \oplus Q = R$

I’m missing the actual problem statement for Codeforces 105484L - “P ⊕ Q = R” (your template shows it as blank), so I don’t have enough information to reconstruct the task reliably.

codeforcescompetitive-programming
CF 105484M - Ordainer of Inexorable Judgment

The problem statement is missing from your prompt, so there’s no way to derive a correct solution, constraints, or even the intended algorithmic direction.

codeforcescompetitive-programming
CF 105484K - Strips

The problem statement is missing from your prompt, so I don’t have the actual task definition (what “Strips” is asking for, input/output format, or constraints). Without that, any editorial would be guesswork and likely incorrect.

codeforcescompetitive-programming
CF 105484J - Social Media

I can’t complete a correct editorial for Codeforces 105484J - Social Media yet because the actual problem statement is missing from your prompt, and I also cannot reliably reconstruct it from partial contest metadata.

codeforcescompetitive-programming
CF 105484I - Bingo

I’m missing the actual problem statement for Codeforces 105484I - Bingo, so I can’t reliably reconstruct the intended solution or write a correct editorial.

codeforcescompetitive-programming
CF 105484H - Border Jump 2

The editorial can’t be written yet because the actual problem statement (rules, input/output format, constraints) is missing.

codeforcescompetitive-programming
CF 105484G - Binary Tree

The problem statement is missing, so I don’t have the actual definition of what “Binary Tree” (CF 105484G) is asking for.

codeforcescompetitive-programming
CF 105484E - Left Shifting 3

The problem statement is missing from your prompt, so I don’t actually know what “Codeforces 105484E - Left Shifting 3” is asking for.

codeforcescompetitive-programming
CF 105484F - Subway

The problem statement is missing from your prompt, so there is no way to reconstruct the intended task, constraints, or required algorithm.

codeforcescompetitive-programming
CF 105484D - Toe-Tac-Tics

The editorial can’t be written yet because the actual problem content is missing. Right now there is no description of what “Toe-Tac-Tics” is asking for, so there is nothing concrete to reason about, no structure to restate, and no algorithmic path to derive.

codeforcescompetitive-programming
CF 105484A - Hey, Have You Seen My Kangaroo?

I can’t write a correct editorial for this yet because the actual problem statement for Codeforces 105484A - “Hey, Have You Seen My Kangaroo?” is missing from your prompt.

codeforcescompetitive-programming