brain

tamnd's digital brain — notes, problems, research

41230 notes

CF 103182L - XorAnd

I can write the full editorial in exactly that format, but I’m missing the actual problem statement for Codeforces 103182L - XorAnd.

codeforcescompetitive-programming
CF 103182J - Strategy

I don’t have the actual statement of Codeforces 103182J - Strategy in your prompt, so I can’t reliably reconstruct the problem, constraints, or solution. Writing a correct editorial without that would require guessing, which would very likely produce a wrong algorithm.

codeforcescompetitive-programming
CF 103182I - Number Spiral

I’m missing the actual problem statement for Codeforces 103182I - Number Spiral, and I can’t reliably reconstruct it from the title alone without risking writing the wrong editorial. Please paste the full statement (or at least input/output format + constraints + a sample).

codeforcescompetitive-programming
CF 103182A - Corporate Issues

A canonical basis $(alpha1,ldots,alphat)$ in Exercise 12 is represented in this section as a selection of $t$ distinguished positions among $n$, equivalently as an $(s,t)$-combination with $n=s+t$, encoded by a binary string $a{n-1}ldots a1a0$ satisfying $sum ai=t$.

codeforcescompetitive-programming
CF 103182H - Spies

I’m missing the actual problem statement for Codeforces 103182H - Spies. Without the description of what the “spies” are doing, what the input represents, and what needs to be computed, any editorial would be guesswork and would very likely be wrong.

codeforcescompetitive-programming
CF 103182G - SigSegv

The problem statement for Codeforces 103182G - SigSegv is missing from your prompt, so there isn’t enough information to reconstruct the task, constraints, or required algorithm.

codeforcescompetitive-programming
CF 103182F - Secure documents

I don’t have the actual statement for Codeforces 103182F - Secure documents in your prompt, so I can’t reliably derive the algorithm, constraints, or examples needed to write a correct editorial.

codeforcescompetitive-programming
CF 103182E - PalTree

The prompt is missing the actual problem statement for Codeforces 103182E - PalTree, so I don’t have enough information to write a correct editorial.

codeforcescompetitive-programming
CF 103182D - Melon Seeds

I don’t have the actual statement for Codeforces 103182D - Melon Seeds in your prompt, and without it I can’t produce a correct editorial. Anything I write would risk inventing rules, which would make the explanation useless for learning or re-derivation.

codeforcescompetitive-programming
CF 103182B - Dragons

The problem statement is missing from your prompt, so there’s no way to reconstruct what “Dragons” (Codeforces 103182B) is asking for.

codeforcescompetitive-programming
CF 103182C - IDE

I’m missing the actual problem statement for Codeforces 103182C - IDE, so I can’t reliably reconstruct the task or produce a correct editorial.

codeforcescompetitive-programming
CF 103185J - Job Allocator

A canonical basis $(alpha1,ldots,alphat)$ in Exercise 12 is represented in this section as a selection of $t$ distinguished positions among $n$, equivalently as an $(s,t)$-combination with $n=s+t$, encoded by a binary string $a{n-1}ldots a1a0$ satisfying $sum ai=t$.

codeforcescompetitive-programming
CF 103185N - Non-Integer Donuts

I don’t have the actual statement of Codeforces 103185N - Non-Integer Donuts in your prompt, and without it I’d be forced to guess the problem structure, which would make the editorial unreliable.

codeforcescompetitive-programming
CF 103185L - Lola's Schedule

I can’t reliably write a correct editorial for this problem without seeing the actual statement. “Codeforces 103185L - Lola’s Schedule” isn’t included in your message, so I don’t know what the input represents, what is being optimized, or even the core task (it could…

codeforcescompetitive-programming
CF 103185M - May I Add a Letter?

The problem statement is missing from your prompt, so I don’t have enough information to write a correct editorial. Right now I only know the title “May I Add a Letter?”, but not: - what the input strings or data are - what operation “add a letter” refers to (insertion?

codeforcescompetitive-programming
CF 103185K - Keylogger

I don’t have the actual statement of Codeforces 103185K - Keylogger, and without it I’d be forced to guess the rules, which would make the editorial unreliable.

codeforcescompetitive-programming
CF 103185I - Impenetrable Wall

I don’t have the actual statement of Codeforces 103185I - Impenetrable Wall available in your prompt, and it’s not safe to reconstruct it from the title alone. To write a correct editorial, I need the full problem description, including input/output format and constraints.

codeforcescompetitive-programming
CF 103185H - Halting Wolf

I can’t write a correct editorial for this yet because the actual problem statement is missing. “Codeforces 103185H - Halting Wolf” isn’t enough on its own to reconstruct the task reliably, and anything I’d write without the full statement would be guesswork.

codeforcescompetitive-programming
CF 103185A - Almost Origami

A canonical basis $(alpha1,ldots,alphat)$ in Exercise 12 is represented in this section as a selection of $t$ distinguished positions among $n$, equivalently as an $(s,t)$-combination with $n=s+t$, encoded by a binary string $a{n-1}ldots a1a0$ satisfying $sum ai=t$.

codeforcescompetitive-programming
CF 103185G - Game of Slots

I can’t write a correct editorial for “Codeforces 103185G - Game of Slots” without the actual problem statement.

codeforcescompetitive-programming
CF 103185D - Dividing Candy

We are given a collection of candy boxes, where each box contains a number of candies that is a power of two. Instead of being given the actual counts directly, we are given exponents: the i-th box contains $2^{Ai}$ candies. Two brothers will split these boxes between them.

codeforcescompetitive-programming
CF 103185F - Fascinating Partitions

I’m missing the actual problem statement for Codeforces 103185F - Fascinating Partitions, so I can’t reliably reconstruct the task or derive a correct solution.

codeforcescompetitive-programming
CF 103185E - Excellent Views

We are given a one-dimensional landscape represented by heights along a line. Each position has a height, and we want to determine which positions are “excellent viewpoints”, meaning they can be seen in an unobstructed way from at least one direction under the natural…

codeforcescompetitive-programming
CF 103185B - Beautiful Mountains

I can’t write a correct editorial for Codeforces 103185B “Beautiful Mountains” without the actual problem statement. Right now the prompt is missing everything that defines the task: what the input represents, what “beautiful” means, and what needs to be computed.

codeforcescompetitive-programming
CF 103185C - Crisis at the Wedding

I can’t reliably write a correct editorial for CF 103185C - Crisis at the Wedding because the actual problem statement is missing from your prompt.

codeforcescompetitive-programming
CF 103186L - 高低奥马哈扑克

We are given a simplified but fully specified game state from Omaha Hi / Lo poker. For each test case, two players, Alice and Bob, each have four private cards, and there are five shared community cards.

codeforcescompetitive-programming
CF 103186K - Alice and Bob-2

We are given several independent games. Each game consists of a small collection of strings made of lowercase letters.

codeforcescompetitive-programming
CF 103186F - 鸡哥的限币令

A World Series scenario in the sense of exercise 10 is a sequence of games between $A$ and $N$ that stops when one side reaches four wins.

codeforcescompetitive-programming
CF 103186J - Alice and Bob-1

We are given a sequence of integers representing card values laid out in a row. Two players, Alice and Bob, alternately pick one card per turn until all cards are taken. Alice always moves first.

codeforcescompetitive-programming
CF 103186I - 对线

We maintain three parallel arrays of length $n$, each position representing a lane on a battlefield. Initially all values are zero.

codeforcescompetitive-programming
CF 103186H - 鸡哥的 AI 驾驶

We are given a set of cars moving along a single infinite line. Each car starts at an integer position, moves with a constant integer velocity, and belongs to a type.

codeforcescompetitive-programming
CF 103186G - 鸡哥的雕像

We are given an array of $n$ positive integers, where each value represents the “growth level” of a plant placed along a street.

codeforcescompetitive-programming
CF 103186D - Zztrans 的班级合照

We are given a multiset of students, each with an integer “height rank” where equal values mean equal height. The task is to arrange all students into two rows of equal length. If there are $n$ students, both rows contain $n/2$ positions indexed from left to right.

codeforcescompetitive-programming
CF 103186E - Zztrans 的庄园

We are simulating a simplified fishing system where each cast produces exactly one fish according to a known probability distribution over fish types.

codeforcescompetitive-programming
CF 103186B - 小 A 的卡牌游戏

Let the canonical bases be represented in the form $(alpha1,dots,alphat)$ as in exercise 12, where each $alphai$ is a binary string of length $n$ with exactly one distinguished position equal to $1$.

codeforcescompetitive-programming
CF 103186C - 小 A 的期末考试

We are given a group of students, each identified by a unique student ID and an initial score. Among them, one student is special, denoted by index m in the input order, and we call this student Xiao A.

codeforcescompetitive-programming
CF 103186A - 小 A 的点面论

We are given two vectors in three-dimensional space, each described by three integer coordinates. The task is to construct any non-zero integer vector that is perpendicular to both given vectors at the same time.

codeforcescompetitive-programming
CF 103192H - 守门员

We are looking at repeated shots in a 2D plane where a player kicks a ball from a fixed point toward a goal represented by two posts on the x-axis. The goal is the open segment between two points on the x-axis, centered at the origin and spanning from x = −w to x = w at y = 0.

codeforcescompetitive-programming
CF 103192L - 零时困境

We are given a hidden permutation of length $n$, meaning the numbers from 1 to $n$ appear exactly once in some unknown order.

codeforcescompetitive-programming
CF 103192A - 出题人的碎碎念

Let the canonical bases be represented in the form $(alpha1,dots,alphat)$ as in exercise 12, where each $alphai$ is a binary string of length $n$ with exactly one distinguished position equal to $1$.

codeforcescompetitive-programming
CF 103192E - 肉夹馍

We are given a binary string that describes a “nested structure” from the innermost layer to the outermost layer.

codeforcescompetitive-programming
CF 103192G - 理财大师

We are given a sequence of future exchange rates between a cryptocurrency and RMB at discrete time moments. At each moment, the price of 1 bitc is known in advance. A trader starts with zero cryptocurrency and unlimited RMB.

codeforcescompetitive-programming
CF 103192B - 页面置换

The task models a classic page replacement scenario from operating systems. We are given a sequence of page requests, where each request asks for a page from a fixed universe of pages. Memory has limited capacity, so it can only hold a small number of pages at once.

codeforcescompetitive-programming
CF 103192D - 法力风暴

We are given several independent test cases. In each test case, there are several spells. Each spell consumes two kinds of resources, a red amount and a blue amount.

codeforcescompetitive-programming
CF 103194C - Игра на дереве

Let the canonical bases be represented in the form $(alpha1,dots,alphat)$ as in exercise 12, where each $alphai$ is a binary string of length $n$ with exactly one distinguished position equal to $1$.

codeforcescompetitive-programming
CF 103194D - Сортировка матрицы

The problem statement section is empty, so there’s not enough information to write a correct editorial. “Сортировка матрицы” could refer to several different tasks (row/column sorting, global flatten-and-sort with constraints, swaps allowed, lexicographic…

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 52

The Takagi function is defined for $0 \le x \le 1$ by \tau(x)=\sum_{k=1}^{\infty}\int_{0}^{x} r_k(t)\,dt, \qquad r_k(t)=(-1)^{\lfloor 2^k t\rfloor}.

taocpmathematicsalgorithmsvolume-4math-project
CF 103194B - Две люстры

A 3-multicombination of ${0,1,dots,n-1}$ is a weakly increasing triple $d1 le d2 le d3,qquad 0 le di le n-1.$ A universal cycle is a cyclic string $a0 a1 dots a{L-1}$ over ${0,dots,n-1}$ such that every length-3 cyclic window $(ai,a{i+1},a{i+2})quad (bmod L)$ appears exactly…

codeforcescompetitive-programming
CF 103194A - Прыжки по шкафам

I don’t have the actual statement of Codeforces 103194A - “Прыжки по шкафам”, and without it any editorial would be guesswork rather than a faithful reconstruction of the solution.

codeforcescompetitive-programming
CF 103195D - Фокус с подмножествами

I can’t reliably produce a correct editorial for Codeforces 103195D - “Фокус с подмножествами” without the exact statement of that specific problem.

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 51

The Takagi function is defined for $0 \le x \le 1$ by \tau(x)=\sum_{k=1}^{\infty}\int_{0}^{x} r_k(t)\,dt, \qquad r_k(t)=(-1)^{\lfloor 2^k t\rfloor}.

taocpmathematicsalgorithmsvolume-4medium
CF 103195B - Вставить текст

We are given several text strings written over the same alphabet, where the first string has a fixed maximum length $m$ and all other strings are no longer than that same bound.

codeforcescompetitive-programming
CF 103195A - Поеду домой

Let $n=s+t$. Exercise 64 considers the set of all strings of length $n$ containing exactly $t$ asterisks and $s$ digits, where each digit is $0$ or $1$.

codeforcescompetitive-programming
CF 103195C - Плитка для ванной

I can’t write a correct editorial for this yet because the actual problem statement is missing. Right now I only know the title “Плитка для ванной”, but without the rules, input/output format, and constraints, anything I write would be guesswork and would…

codeforcescompetitive-programming
CF 103196I - Доставка посылок

We are given a sequence of parcels arriving over time, where each parcel has a weight and a structural limit that behaves like a fragile stacking system.

codeforcescompetitive-programming
CF 103196J - Тараканы общежития

The problem describes a dormitory building modeled as a collection of rooms connected by corridors, where each corridor connects two rooms in a tree-like structure. The building is heavily affected by cockroaches that can move freely along the connections between rooms.

codeforcescompetitive-programming
CF 103196F - Футболки на олимпиаду

Let $G$ be the multigraph whose vertices are ${0,1,2,3,4,5,6}$ and whose edges are the $28$ dominoes of the double-six set, namely one edge between $i$ and $j$ for each $0 le i le j le 6$, including one loop at each vertex.

codeforcescompetitive-programming
CF 103196E - Проблема останова

The problem statement is missing, so there isn’t enough information to reconstruct the solution. “Codeforces 103196E - Проблема останова” alone isn’t sufficient because Codeforces problem IDs aren’t globally descriptive, and multiple problems can share…

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 50

The Takagi function is defined for $0 \le x \le 1$ by \tau(x)=\sum_{k=1}^{\infty}\int_{0}^{x} r_k(t)\,dt, \qquad r_k(t)=(-1)^{\lfloor 2^k t\rfloor}.

taocpmathematicsalgorithmsvolume-4hm-medium
CF 103196H - Украшение дома

I can’t reliably write a correct editorial for Codeforces 103196H - “Украшение дома” without the actual problem statement.

codeforcescompetitive-programming
CF 103196G - Тир

I can write the full Codeforces-style editorial in exactly that format, but I’m missing the actual problem content for 103196G - “Тир”.

codeforcescompetitive-programming
CF 103196B - Проверка олимпиады

I don’t have the actual statement of Codeforces 103196B (“Проверка олимпиады”) in your prompt, so I can’t safely reconstruct or explain the solution without risking hallucinating the problem.

codeforcescompetitive-programming
CF 103196C - Дед и мопед

Let $G$ be the multigraph whose vertices are ${0,1,2,3,4,5,6}$ and whose edges are the $28$ dominoes of the double-six set, namely one edge between $i$ and $j$ for each $0 le i le j le 6$, including one loop at each vertex.

codeforcescompetitive-programming
CF 103196D - Задача для разминки рук

The problem statement is missing from your prompt, so I can’t reconstruct Codeforces 103196D or write a correct editorial yet. Right now I don’t know what the input represents, what operations are allowed, or what needs to be computed.

codeforcescompetitive-programming
CF 103196A - Re: Fwd: Про чайник

I can’t reliably write a correct Codeforces editorial for this problem yet because the actual statement (what the input describes, what needs to be computed, and the constraints) is missing.

codeforcescompetitive-programming
CF 103202K - Scholomance Academy

Let $G$ be the multigraph whose vertices are ${0,1,2,3,4,5,6}$ and whose edges are the $28$ dominoes of the double-six set, namely one edge between $i$ and $j$ for each $0 le i le j le 6$, including one loop at each vertex.

codeforcescompetitive-programming
CF 103202I - Rise of Shadows

I can’t write a correct editorial for “Codeforces 103202I - Rise of Shadows” without the actual problem statement. Right now the prompt only includes metadata, but no description of the rules, inputs, or required output.

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 49

Let $q$ be a primitive $m$th root of unity, so $q^m=1$ and $q^j\neq 1$ for $1\le j<m$.

taocpmathematicsalgorithmsvolume-4hm-medium
CF 103202M - United in Stormwind

Connection interrupted. Waiting for the complete answer

codeforcescompetitive-programming
CF 103202L - Forged in the Barrens

Let $G{s,t}$ denote the graph whose vertices are all subcubes of length $s+t$ having $s$ digits in ${0,1}$ and $t$ asterisks, with edges given by the transformations $ast 0 leftrightarrow 0ast$, $ast 1 leftrightarrow 1ast$, and $0 leftrightarrow 1$.

codeforcescompetitive-programming
CF 103202G - The Witchwood

Let $G{s,t}$ denote the graph whose vertices are all subcubes of length $s+t$ having $s$ digits in ${0,1}$ and $t$ asterisks, with edges given by the transformations $ast 0 leftrightarrow 0ast$, $ast 1 leftrightarrow 1ast$, and $0 leftrightarrow 1$.

codeforcescompetitive-programming
CF 103202J - Descent of Dragons

We are maintaining an array of size $n$, initially all zeros, where values only ever increase. However, increments are not applied uniformly. Instead, a training operation targets a value $x$ and only increments those positions that currently equal $x$ inside a segment.

codeforcescompetitive-programming
CF 103202H - The Boomsday Project

I can’t write a correct editorial for this yet because the actual problem content is missing. Right now, I only see the title, but there is no statement, no input/output description, and no constraints.

codeforcescompetitive-programming
CF 103202F - Kobolds and Catacombs

I can’t produce a correct editorial for this problem yet because the actual problem statement is missing. “Codeforces 103202F - Kobolds and Catacombs” alone doesn’t contain enough information to reconstruct the task reliably.

codeforcescompetitive-programming
CF 103202E - Knights of the Frozen Throne

The problem statement is missing from the prompt, so I can’t reconstruct what “Knights of the Frozen Throne” is asking for or derive a correct solution.

codeforcescompetitive-programming
CF 103202C - Mean Streets of Gadgetzan

Connection interrupted. Waiting for the complete answer

codeforcescompetitive-programming
CF 103202D - Journey to Un'Goro

The problem statement is missing from your prompt, so there isn’t enough information to reconstruct the task or derive a correct solution.

codeforcescompetitive-programming
CF 103202A - The Grand Tournament

I can’t responsibly write a full Codeforces editorial yet because the actual problem statement for Codeforces 103202A - The Grand Tournament is missing from your prompt, and it’s not included in what you provided.

codeforcescompetitive-programming
CF 103202B - Whispers of the Old Gods

I can’t produce a correct editorial for this problem because the actual problem statement is missing. Right now I don’t know what the input represents, what transformation or query is required, or what constraints define the intended solution.

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 48

Let $[n]={0,1,\dots,n-1}$ and let $\binom{[n]}{t}$ denote the set of all $t$-combinations.

taocpmathematicsalgorithmsvolume-4math-medium
CF 103230A - Torty and Shields

Let $n=s+t$ and let the ground positions be ${0,1,dots,n-1}$. A configuration is a word $x0x1cdots x{n-1}$ over ${0,1,ast}$ containing exactly $t$ asterisks. The set of all such configurations has size $2^sbinom{s+t}{t}$.

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 47

Let $[n]={0,1,\dots,n-1}$ and let $\binom{[n]}{t}$ denote the set of all $t$-combinations.

taocpmathematicsalgorithmsvolume-4hard
CF 103230B - Blue Puppy and UFOs

The problem statement for “Codeforces 103230B - Blue Puppy and UFOs” is not included in your message, so I don’t have enough information to write a correct editorial.

codeforcescompetitive-programming
CF 103241T - Vivy's Singularity Project

Let $n=s+t$ and let the ground positions be ${0,1,dots,n-1}$. A configuration is a word $x0x1cdots x{n-1}$ over ${0,1,ast}$ containing exactly $t$ asterisks. The set of all such configurations has size $2^sbinom{s+t}{t}$.

codeforcescompetitive-programming
CF 103241Y - Lattice MST

I can’t write a correct editorial for “Lattice MST” without the actual problem statement. Right now there’s no description of what the grid/lattice looks like, what edges exist, what defines the MST cost, or what inputs/outputs are.

codeforcescompetitive-programming
CF 103241X - Endeavor's Agency

I can’t write a correct editorial for this problem because the actual problem statement (what operations are allowed, what is given in the input, and what must be computed) is missing.

codeforcescompetitive-programming
CF 103241W - Sol's Problem Meeting

I don’t have the actual statement for Codeforces 103241W - Sol's Problem Meeting, so I can’t reconstruct the problem or derive a correct solution without guessing.

codeforcescompetitive-programming
CF 103241V - Thomas Game

I don’t have the actual problem statement for Codeforces 103241V - Thomas Game, so I can’t correctly derive the algorithm, constraints, or examples.

codeforcescompetitive-programming
CF 103241U - Rengoku's Flame Breathing

The problem statement is missing from your prompt, so there is no way to derive a correct algorithm, complexity analysis, or implementation details.

codeforcescompetitive-programming
CF 103241S - Cooked Fish (Hard Version)

I’m missing the actual problem statement, input/output description, and constraints, so I can’t reliably reconstruct the task or write a correct editorial.

codeforcescompetitive-programming
CF 103241R - Kakyoin's Painting

The problem statement is missing, so I can’t accurately reconstruct the solution or write a correct editorial. Right now I only know the title “Kakyoin’s Painting”, but there is no information about: - what the input represents (grid, sequence, graph, etc.

codeforcescompetitive-programming
CF 103241H - Position of Set

Let $n=s+t$ and let the ground positions be ${0,1,dots,n-1}$. A configuration is a word $x0x1cdots x{n-1}$ over ${0,1,ast}$ containing exactly $t$ asterisks. The set of all such configurations has size $2^sbinom{s+t}{t}$.

codeforcescompetitive-programming
CF 103241Q - Tree Width

I’m missing the actual problem statement for Codeforces 103241Q - Tree Width, so I can’t safely reconstruct the intended solution or write a correct editorial.

codeforcescompetitive-programming
CF 103241P - Abc's (Hard Version)

The problem statement is missing from the prompt, so there’s no way to reconstruct the intended algorithm or constraints for Codeforces 103241P.

codeforcescompetitive-programming
CF 103241O - Kanna's Field of Flowers

The problem statement for Codeforces 103241O - Kanna's Field of Flowers is missing from your prompt, so I don’t have the actual task definition, constraints, or input/output format needed to write a correct editorial.

codeforcescompetitive-programming
CF 103241N - Teleport

I can’t write a correct editorial without the actual problem statement. Right now the prompt only includes the template and metadata, but there’s no description of what “Teleport” asks, what the input represents, or what needs to be computed.

codeforcescompetitive-programming
CF 103241M - Shion's Feast

The prompt doesn’t include the actual problem statement for Codeforces 103241M - Shion's Feast, so there’s no way to correctly reconstruct the logic, constraints, or required algorithm.

codeforcescompetitive-programming
CF 103241L - Cooked Fish (Easy Version)

The problem statement for “Codeforces 103241L - Cooked Fish (Easy Version)” is not included in your message, so I don’t have the actual task definition, input format, or constraints needed to write a correct editorial.

codeforcescompetitive-programming
CF 103241K - Necklaces

The problem statement is missing from your prompt, so I don’t have enough information to write a correct editorial.

codeforcescompetitive-programming
CF 103241J - Making Stonks

I cannot reliably produce a correct editorial for “Codeforces 103241J - Making Stonks” because the actual problem statement is not available in the prompt, and the accessible information from Codeforces is inconsistent with that specific index.

codeforcescompetitive-programming