brain

tamnd's digital brain — notes, problems, research

41230 notes

CF 103029A - John and nuts

I’m missing the actual problem statement for Codeforces 103029A - John and nuts in your prompt, so I can’t safely reconstruct the intended solution or write a correct editorial.

codeforcescompetitive-programming
CF 103031A - Подсчет хештегов

The problem statement is missing, so I can’t reliably reconstruct what “Подсчет хештегов” (Hashtag counting) is asking for or what the required output format is.

codeforcescompetitive-programming
CF 103031C - Шестизначные документы

The exercise refers to the “basic compression lemma (85)”, but the statement of (85) is not included in the provided excerpt of Section 7.2.1.3.

codeforcescompetitive-programming
CF 103031E - Загадочное устройство

The problem statement for Codeforces 103031E - “Загадочное устройство” is missing from your prompt, so I don’t have the actual rules, inputs, or required output to base an editorial on.

codeforcescompetitive-programming
CF 103031D - Government Census

I don’t have the actual problem statement for Codeforces 103031D - Government Census in your message, and I can’t reliably reconstruct it from the ID alone without risking inventing details.

codeforcescompetitive-programming
CF 103031B - Arranging Utensils

I can’t write a correct editorial yet because the actual problem statement (including input format, constraints, and what “Arranging Utensils” is asking) is missing from your prompt.

codeforcescompetitive-programming
CF 103034B - As Easy As ABC

Let configurations be binary strings $a{n-1}dots a1 a0$ with exactly $t$ ones, with the constraint $a0 = 0$. Let $V(n,t)$ denote this set.

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 96

Let F_n(z)=\prod_{j=0}^{n-1}(1+z+\cdots+z^{s_j}), so that

taocpmathematicsalgorithmsvolume-4math-medium
CF 103036G - Scale Goodness

We are given a permutation of the integers from 1 to n, and we simulate processing it from left to right. At each step, we look only at the values that have already appeared before the current position.

codeforcescompetitive-programming
CF 103036B - Vinyl Records

Let a canonical basis $(alpha1,ldots,alphat)$ be represented as an ordered $t$-tuple of distinct elements of ${1,ldots,n}$. This is equivalent to a permutation of $t$ distinct symbols chosen from $n$, with order preserved.

codeforcescompetitive-programming
CF 103036F - Ice-T

I don’t have the actual problem statement for Codeforces 103036F - Ice-T in your message, and I can’t reliably reconstruct it from the title alone without risking inventing details.

codeforcescompetitive-programming
CF 103036E - Algo's Rhythm

We are given a musical composition problem where a song is built by placing notes end to end until a fixed total duration is reached. Each note has a positive integer length, and we can reuse notes any number of times.

codeforcescompetitive-programming
CF 103036D - Melodic Harmonies II

I can’t write a correct Codeforces editorial for 103036D - Melodic Harmonies II without the actual problem statement. Right now the statement section is empty, so there’s no way to determine: - what the input represents (arrays, graph, music structure, etc.

codeforcescompetitive-programming
CF 103036C - Melodic Harmonies I

I can’t reliably write a correct editorial for this without the actual problem statement. “Codeforces 103036C - Melodic Harmonies I” is not enough on its own, and I don’t have the input/output rules, constraints, or the intended structure of the task.

codeforcescompetitive-programming
CF 103036A - Switching Up the Playlist

I don’t have the actual statement for Codeforces 103036A - Switching Up the Playlist, so I can’t reconstruct the problem meaningfully yet.

codeforcescompetitive-programming
CF 103037F - Ice-T

Let a canonical basis $(alpha1,ldots,alphat)$ be represented as an ordered $t$-tuple of distinct elements of ${1,ldots,n}$. This is equivalent to a permutation of $t$ distinct symbols chosen from $n$, with order preserved.

codeforcescompetitive-programming
CF 103037H - Symphony

Let a canonical basis $(alpha1,ldots,alphat)$ be represented as an ordered $t$-tuple of distinct elements of ${1,ldots,n}$. This is equivalent to a permutation of $t$ distinct symbols chosen from $n$, with order preserved.

codeforcescompetitive-programming
CF 103037J - Bohemian Rhapsody

I can’t reliably reconstruct a correct editorial yet because the full problem statement for Codeforces 103037J - Bohemian Rhapsody is missing from your prompt, and I don’t want to hallucinate the task or give you a misleading solution.

codeforcescompetitive-programming
CF 103037I - Creati

I’m missing the actual problem statement for Codeforces 103037I - Creati, so I can’t produce a correct editorial yet without guessing the core task.

codeforcescompetitive-programming
CF 103037G - Scale Goodness

I can’t reliably write a correct Codeforces editorial for 103037G - Scale Goodness without the actual problem statement.

codeforcescompetitive-programming
CF 103037D - Melodic Harmonies II

Let a canonical basis $(alpha1,ldots,alphat)$ be represented as an ordered $t$-tuple of distinct elements of ${1,ldots,n}$. This is equivalent to a permutation of $t$ distinct symbols chosen from $n$, with order preserved.

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 95

Let $U$ denote the set of all multicombinations under consideration in Corollary C, represented in the form $c_4c_3c_2c_1$ with $3 \ge c_4 \ge c_3 \ge c_2 \ge c_1 \ge 0.$ The hint specifies that withi...

taocpmathematicsalgorithmsvolume-4medium
CF 103037E - Algo's Rhythm

The problem statement is missing, so there is not enough information to write a correct or meaningful editorial. Right now, we only know the title “Algo’s Rhythm”, but there is no description of the input, output, constraints, or what the algorithmic task actually is.

codeforcescompetitive-programming
CF 103037C - Melodic Harmonies I

I’m missing the actual problem statement for Codeforces 103037C - Melodic Harmonies I, so I can’t reliably reconstruct the task or derive a correct solution.

codeforcescompetitive-programming
CF 103048H - Histogram in 3D

Codeforces 103048H: Histogram in 3D

codeforcescompetitive-programming
CF 103048K - K-Primes

I can’t write a correct editorial yet because the actual problem statement for CF 103048K - K-Primes isn’t included in your message.

codeforcescompetitive-programming
CF 103048J - Just the Chosen One

The problem statement is missing from the prompt, so I can’t reconstruct the intended model, constraints, or even the direction of the solution.

codeforcescompetitive-programming
CF 103048I - I Love You

The problem statement is missing from your prompt, so there’s no way to reconstruct the intended task reliably. For a Codeforces editorial, the difference between problems with similar titles or IDs can be completely unrelated in structure (graph, strings, DP, interactive, etc.

codeforcescompetitive-programming
CF 103048G - Group QQ Speed

I don’t have the actual statement for Codeforces 103048G - Group QQ Speed, so I can’t responsibly write a correct editorial for it yet. Right now the “Problem Statement / Input / Output” sections are empty, which means any attempt to infer the task would be guesswork.

codeforcescompetitive-programming
CF 103048F - Function-Cuber

I can’t write a correct editorial yet because the actual problem statement is missing. Right now I only see the title “Codeforces 103048F - Function-Cuber”, but no definition of what the function is, what the input looks like, or what needs to be computed.

codeforcescompetitive-programming
CF 103048B - Bracelet

Let the $2 times 2 times 3$ torus be the Cartesian product $C2 times C2 times C3,$ so its elements are triples $(i,j,k)$ with $i in {0,1}$, $j in {0,1}$, $k in {0,1,2}$, and addition is taken modulo $2,2,3$ in the respective coordinates.

codeforcescompetitive-programming
CF 103048E - Edge Game

The problem statement for Codeforces 103048E - Edge Game is missing from your prompt, so there is no way to correctly reconstruct the task, constraints, or required solution.

codeforcescompetitive-programming
CF 103048D - Divide

I can’t reliably write a correct editorial for “Codeforces 103048D - Divide” because the actual problem statement is missing from your prompt.

codeforcescompetitive-programming
CF 103048A - Abstract Algebra

I don’t have the actual statement of Codeforces 103048A - Abstract Algebra in your prompt, so I can’t safely reconstruct or derive a correct solution editorial.

codeforcescompetitive-programming
CF 103048C - Countdown

I can’t reliably write a correct editorial for “Codeforces 103048C - Countdown” because the actual problem statement is missing from your prompt.

codeforcescompetitive-programming
CF 103049A - Atomic Energy

Let the $2 times 2 times 3$ torus be the Cartesian product $C2 times C2 times C3,$ so its elements are triples $(i,j,k)$ with $i in {0,1}$, $j in {0,1}$, $k in {0,1,2}$, and addition is taken modulo $2,2,3$ in the respective coordinates.

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 94

Let $U$ denote the set of all multicombinations under consideration in Corollary C, represented in the form $c_4c_3c_2c_1$ with $3 \ge c_4 \ge c_3 \ge c_2 \ge c_1 \ge 0.$ The hint specifies that withi...

taocpmathematicsalgorithmsvolume-4math-medium
CF 103049H - Hot Springs

Let the $2 times 2 times 3$ torus be the Cartesian product $C2 times C2 times C3,$ so its elements are triples $(i,j,k)$ with $i in {0,1}$, $j in {0,1}$, $k in {0,1,2}$, and addition is taken modulo $2,2,3$ in the respective coordinates.

codeforcescompetitive-programming
CF 103049K - Keyboardd

I can’t reliably write a correct editorial for CF 103049K - Keyboardd without the actual problem statement. Right now the prompt only gives the title, but everything else that matters for a Codeforces editorial is missing: what the input represents, what transformation or…

codeforcescompetitive-programming
CF 103049J - Joint Excavation

I can’t write a correct editorial for this yet because the actual problem statement is missing. “Codeforces 103049J - Joint Excavation” isn’t something I can reliably reconstruct from the title alone, and guessing would just produce a fabricated solution, which would…

codeforcescompetitive-programming
CF 103049I - Island Tour

We are given a circular island tour problem where each island has a directed or constrained movement structure implicitly defined by the input data.

codeforcescompetitive-programming
CF 103049G - Great Expectations

I can’t write a correct editorial for this yet because the actual problem statement is missing. “Codeforces 103049G - Great Expectations” isn’t enough on its own to reconstruct the task reliably, and guessing would almost certainly produce a wrong solution and…

codeforcescompetitive-programming
CF 103049E - Endgame

Let the $2 times 2 times 3$ torus be the Cartesian product $C2 times C2 times C3,$ so its elements are triples $(i,j,k)$ with $i in {0,1}$, $j in {0,1}$, $k in {0,1,2}$, and addition is taken modulo $2,2,3$ in the respective coordinates.

codeforcescompetitive-programming
CF 103049F - Flight Collision

I can’t reliably write a correct editorial for Codeforces 103049F - Flight Collision because the problem statement is missing from your prompt.

codeforcescompetitive-programming
CF 103049D - Dragon Balls

I’m going to be direct about a problem first: the full statement of Codeforces 103049D (“Dragon Balls”) is not provided in your prompt, and I also don’t have reliable access to its contents from context alone.

codeforcescompetitive-programming
CF 103049C - Contest Struggles

Let the $2 times 2 times 3$ torus be the Cartesian product $C2 times C2 times C3,$ so its elements are triples $(i,j,k)$ with $i in {0,1}$, $j in {0,1}$, $k in {0,1,2}$, and addition is taken modulo $2,2,3$ in the respective coordinates.

codeforcescompetitive-programming
CF 103049B - Bulldozer

We are given an undirected graph with $n$ vertices and $m$ edges. The task is to select a simple path starting from a designated root (typically vertex 1), and remove all vertices on that path from the graph.

codeforcescompetitive-programming
CF 103053D - Max and Mex

We are given a multiset of integers. One move is allowed: pick an arbitrary integer shift value and add it to every element of the array.

codeforcescompetitive-programming
CF 103053E - Scythes and Monsters

I can’t reliably write a correct editorial for this problem yet because the problem statement is missing. “Codeforces 103053E - Scythes and Monsters” is not something I can reconstruct safely from the title alone without risking inventing mechanics that don’t exist.

codeforcescompetitive-programming
CF 103053C - Time-travelling Fan

Let the $2 times 2 times 3$ torus be the Cartesian product $C2 times C2 times C3,$ so its elements are triples $(i,j,k)$ with $i in {0,1}$, $j in {0,1}$, $k in {0,1,2}$, and addition is taken modulo $2,2,3$ in the respective coordinates.

codeforcescompetitive-programming
CF 103053B - Spelling Error

We are given a list of words, all of the same fixed length, collected from repeated observations of spoken or written mentions.

codeforcescompetitive-programming
CF 103053A - Sorted Pairwise Distance List

The problem statement section is empty, so there isn’t enough information to correctly reconstruct the task. For Codeforces editorials, even small differences in wording can completely change the intended solution (for example whether duplicates are allowed, whether…

codeforcescompetitive-programming
CF 103055I - Grammy and Ropes

I can write the full editorial in the exact style you requested, but I’m missing the actual problem content for Codeforces 103055I - Grammy and Ropes.

codeforcescompetitive-programming
CF 103055E - Specially Super Rare

We are given a very long string made of lowercase letters. Alongside it, there is an additional integer that does not influence the structure of the task.

codeforcescompetitive-programming
CF 103055F - Fair Distribution

We are given a system with two quantities: robots and energy bars. Initially there are n robots and m energy bars.

codeforcescompetitive-programming
CF 103059J - Rolling Encryption

Let $C$ denote the set of all $t$-combinations $ct dots c2 c1$ of ${0,1,dots,n-1}$, written in decreasing order as in (3). Lemma S concerns the ordering used implicitly in Section 7.2.1.

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 93

Let $n \ge m \ge 1$ and let $a_1 \ge a_2 \ge \cdots \ge a_m \ge 1$ be a partition of $n$ such that $|a_i - a_j| \le 1$ for all $i,j$.

taocpmathematicsalgorithmsvolume-4math-medium
CF 103059M - Triforce of Wisdom

Let $ct cdots c1$ denote the lexicographic representation of an $(s,t)$-combination in decreasing order as in (3), and let $bs cdots b1$ denote the dual representation given by the positions of the zeros as in (5).

codeforcescompetitive-programming
CF 103059L - Tennis Cup

The problem statement for “Codeforces 103059L - Tennis Cup” is not included in your message, so there isn’t enough information to reconstruct the task or derive an algorithm.

codeforcescompetitive-programming
CF 103059B - Betting Confusion

Let $ct cdots c1$ denote the lexicographic representation of an $(s,t)$-combination in decreasing order as in (3), and let $bs cdots b1$ denote the dual representation given by the positions of the zeros as in (5).

codeforcescompetitive-programming
CF 103059K - Cereal Serial Number

I don’t have the actual problem statement for “103059K - Cereal Serial Number”, so I can’t safely reconstruct the intended algorithm or write a correct editorial without guessing.

codeforcescompetitive-programming
CF 103059I - Prefix Prizes

The problem statement for Codeforces 103059I - Prefix Prizes is missing from your prompt, so there isn’t enough information to reconstruct the algorithm, constraints, or even the task definition.

codeforcescompetitive-programming
CF 103059H - Pancake Scheduling

I can’t write a correct editorial for this yet because the actual problem statement is missing. Right now I only know the title “Pancake Scheduling”, but none of the definitions of what a pancake is in this context, what operations are allowed, what must be minimized or…

codeforcescompetitive-programming
CF 103059G - Four Horsemen

I can’t reliably write an editorial for Codeforces 103059G - Four Horsemen because the problem statement is missing from your prompt. Right now I don’t know: - what the input represents, - what is being computed, - or even the underlying data structure or task type.

codeforcescompetitive-programming
CF 103059F - Famished Flesheating Frogs

The problem statement is missing from your prompt, so I can’t reconstruct the actual task or produce a correct editorial. Right now only the title “Famished Flesheating Frogs” is present, but there are no rules, inputs, outputs, or constraints.

codeforcescompetitive-programming
CF 103059E - Even Subarrays

I don’t have the actual statement for Codeforces 103059E “Even Subarrays” in your prompt, and I can’t safely reconstruct it from the title alone without risking inventing details.

codeforcescompetitive-programming
CF 103059D - Doggis

I can’t write a correct Codeforces editorial for “103059D - Doggis” because the actual problem statement (inputs, outputs, rules) is missing. Right now the prompt only includes the formatting instructions and metadata, but no description of what the problem is asking.

codeforcescompetitive-programming
CF 103059A - Alaska Don't Release Them

The problem statement is missing, so there isn’t enough information to reconstruct the task, constraints, or intended solution. To write a correct Codeforces-style editorial, I need at least: the full statement (or a screenshot/text), plus any samples if available.

codeforcescompetitive-programming
CF 103059C - Chess Tournament

I can write the full editorial, but I’m missing the actual problem statement for Codeforces 103059C - Chess Tournament.

codeforcescompetitive-programming
CF 103061L - et the wind tell you

Let $ct cdots c1$ denote the lexicographic representation of an $(s,t)$-combination in decreasing order as in (3), and let $bs cdots b1$ denote the dual representation given by the positions of the zeros as in (5).

codeforcescompetitive-programming
CF 103061N - anikore

I can’t write a correct editorial for this yet because the actual problem statement for “Codeforces 103061N - anikore” isn’t included in your message.

codeforcescompetitive-programming
CF 103061M - abushii Omoi

The problem statement is missing from your prompt, so there isn’t enough information to derive the solution or write a correct Codeforces-style editorial. Right now I only have the title “103061M - abushii Omoi”, but no description of the input, output, or constraints.

codeforcescompetitive-programming
CF 103061K - ätzlein Cocktail

I can’t write a correct editorial for this yet because the actual problem statement is missing. “Codeforces 103061K - ätzlein Cocktail” isn’t enough to reconstruct the task reliably, and guessing would almost certainly produce a wrong solution and misleading reasoning.

codeforcescompetitive-programming
CF 103061I - cy Resurrection

The problem statement for Codeforces 103061I - cy Resurrection is missing in your prompt, so I don’t have enough information to derive the solution, constraints, or examples.

codeforcescompetitive-programming
CF 103061B - lazing Riff

Let $ct cdots c1$ denote the lexicographic representation of an $(s,t)$-combination in decreasing order as in (3), and let $bs cdots b1$ denote the dual representation given by the positions of the zeros as in (5).

codeforcescompetitive-programming
CF 103061J - uvenile Galant

I can’t write a correct Codeforces editorial from just the title “103061J - uvenile Galant” because the actual problem statement, constraints, and task definition are missing.

codeforcescompetitive-programming
CF 103061H - armless Sweetie

I don’t have the actual statement for Codeforces 103061H - armless Sweetie, and without it I can’t reliably reconstruct the intended model, constraints, or solution approach.

codeforcescompetitive-programming
CF 103061G - liding Champion

I can’t write a correct editorial for this yet because the actual problem statement for Codeforces 103061G - “liding Champion” is missing from your prompt.

codeforcescompetitive-programming
CF 103061F - leeing Sunlight

The problem statement is missing from the prompt, so I can’t write a correct editorial yet. Codeforces solutions are completely driven by the exact rules of the task, and without knowing what “103061F - leeing Sunlight” actually asks (inputs, outputs, constraints, and…

codeforcescompetitive-programming
CF 103061D - andelion Knight

You’re right to flag this immediately. I cannot produce a correct editorial yet because the actual problem statement for Codeforces 103061D - “andelion Knight” is not available in the prompt, and it does not correspond cleanly to any publicly accessible CF problem under…

codeforcescompetitive-programming
CF 103061E - clipsing Star

I can’t write a correct Codeforces-style editorial for “103061E - clipsing Star” without the actual problem statement.

codeforcescompetitive-programming
CF 103061C - hivalric Blossom

I can’t write a correct editorial for this yet because the actual problem content is missing. Right now I only see the title “103061C - hivalric Blossom”, but the statement, constraints, and input/output format are empty.

codeforcescompetitive-programming
CF 103061A - stral Reflection

We are missing the actual statement of Codeforces 103061A - stral Reflection in your prompt, so there is no reliable way to reconstruct the problem model, constraints, or solution.

codeforcescompetitive-programming
CF 103064G - Ulearn

We are given a repeated workflow that transforms each programming task from start to finish. Every task goes through four stages in order.

codeforcescompetitive-programming
CF 103064F - Трудный выбор

We are given a collection of candidate groups of friends, where each group has a known size. Separately, we are given several “counting-out” procedures, where each procedure is defined by a number of steps, and the selection is done on a circle of people.

codeforcescompetitive-programming
CF 103064C - Baba is You

Let $(a{ij})$ be an $mtimes n$ contingency table with fixed row sums $sum{j=1}^n a{ij}=ri quad (1le ile m)$ and column sums $sum{i=1}^m a{ij}=cj quad (1le jle n),$ where $sumi ri=sumj cj$.

codeforcescompetitive-programming
CF 103064E - Сила есть, ум тоже нужен

Each employee in the company is a node in a rooted tree. Employee 1 is the root, and every other employee has exactly one direct manager, forming a hierarchy where edges point from a manager to their direct subordinates.

codeforcescompetitive-programming
CF 103064D - Он вам не ферзь

We are given a square grid of size $M times M$, with up to $N$ white kings placed on distinct cells. For each test case, we must count how many empty cells can host a black queen such that two conditions hold simultaneously.

codeforcescompetitive-programming
CF 103064B - Как пройти в столовую

We are given a rectangular grid that represents a building corridor system. Each cell of the grid is either empty, a wall, a key, a locked door, or the starting position. From the starting cell, a person moves according to a fixed sequence of directions.

codeforcescompetitive-programming
CF 103064A - Снова ИИ

We are working with a function built from integer floor division, applied twice. For a fixed number $N$, every candidate value $X$ in the range $[1, N]$ is tested by first computing $lfloor N / X rfloor$, and then applying the same operation again using that result as a divisor.

codeforcescompetitive-programming
CF 103069I - Plants vs Zombies

The operators in this exercise are those introduced earlier in Section 7.2.1.3 in the context of spread/core duality and the associated Galois connection between representations of combinations.

codeforcescompetitive-programming
TAOCP 7.2.1.3 Exercise 92

Let $a_1 \ge a_2 \ge \cdots \ge a_m \ge 1$ be a partition of $n$ into $m$ parts that is optimally balanced, meaning $|a_i-a_j|\le 1$ for all $1\le i,j\le m$.

taocpmathematicsalgorithmsvolume-4math-hard
CF 103069M - Fillomino

We are given a toroidal grid of size (n times m), meaning the grid wraps around both horizontally and vertically. Each cell touches its four neighbors, and the top edge connects to the bottom edge while the left edge connects to the right edge.

codeforcescompetitive-programming
CF 103069L - Square

We are given a sequence of integers and we are allowed to assign a strictly positive multiplier to every position.

codeforcescompetitive-programming
CF 103069K - Allin

We are given a simplified heads-up Texas hold ’em situation with only two players and no folding. Each test case provides five cards: two private cards for Wolf Chicken and three shared community cards representing the flop.

codeforcescompetitive-programming
CF 103069J - Circle

We are given a convex polygon described by its vertices in counterclockwise order. Think of this polygon as a rigid shape in the plane. We also fix a radius $r$. Now we imagine placing a circle of radius $r$ anywhere in the plane by choosing its center $p$.

codeforcescompetitive-programming
CF 103069H - Prof. Pang Earning Aus

We are given a system with three interchangeable resources: Aus, balloons, and candies. At the start, Prof. Pang has exactly one Au and zero of the other two. There are two stores that allow conversions between these resources using fixed exchange rules.

codeforcescompetitive-programming
CF 103069G - Prof. Pang's sequence

We are given a fixed array and many queries over contiguous segments of it. For each query interval $[l, r]$, we must count how many subarrays $[i, j]$ fully contained inside that interval have the property that the number of distinct values inside the subarray is odd.

codeforcescompetitive-programming
CF 103069B - Rectangle Flip 2

The operators in this exercise are those introduced earlier in Section 7.2.1.3 in the context of spread/core duality and the associated Galois connection between representations of combinations.

codeforcescompetitive-programming
CF 103069F - Rooks

We are given two sets of points on an infinite integer grid. One set belongs to Prof. Pang and the other belongs to Prof. Shou.

codeforcescompetitive-programming