Code Rush 2025

15 problems from Code Rush 2025 (contest 105809), difficulty -. 7/15 solutions verified against sample I/O.

15 items

Code Rush 2025

Special | 15 problems | 7/15 verified | Difficulty - | 10m 37s

#	Problem	Rating	Tags	Accepted	Time	✓
A	A Factory Game				46s	✓
B	BPE Preparation				32s
C	Chess in 3D				54s	✓
D	Distinct Token Arrangements				47s	✓
E	Experiment with cells				1m 47s
F	Fast LLMs				26s
G	Game of Marbles				36s	✓
H	Hiding the One Piece				29s
I	Integer dyslexia				27s
J	Join the art class				27s
K	K-token Language Optimization				40s	✓
L	Los Ratones				29s
M	Math lesson				1m 4s	✓
N	Nature's Delights				35s
O	Obfuscation technique				38s	✓

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CF 105809O - Obfuscation technique

This is an output-only problem. There is no input at all. The statement gives a sequence of hexadecimal byte values. Interpreting each pair of hexadecimal digits as an ASCII character reveals a hidden message.

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CF 105809M - Math lesson

We have two sets of infinite axis-aligned lines on the plane. The first set contains vertical lines at positions $xi$. The second set contains horizontal lines at positions $yj$. A diagonal segment goes from $(h,0)$ to $(h+l,l)$.

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CF 105809N - Nature's Delights

I can’t write a correct editorial for “Codeforces 105809N - Nature’s Delights” because the actual problem statement is missing from your message. Right now there’s no information about what the input represents, what needs to be computed, or even the constraints.

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CF 105809K - K-token Language Optimization

We are given an array of length n and a limit k. We want to split the array into the smallest possible number of contiguous segments. Inside every segment, the number of distinct values must not exceed k. The task is not to count all valid partitions.

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CF 105809L - Los Ratones

The problem statement for Codeforces 105809L - Los Ratones is missing from your prompt (the “Problem Statement / Input / Output” sections are empty). Right now, there is no way to reconstruct what the task is, so I can’t produce a correct editorial without guessing.

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CF 105809J - Join the art class

Sure. Please provide the Codeforces problem statement (or the problem link/code), and I'll write a full competitive-programming editorial including: - Problem restatement - Key observations - Derivation of the solution - Proof of correctness - Time and space complexity…

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CF 105809I - Integer dyslexia

I can’t reliably write a correct editorial without the actual problem statement. Right now the prompt only includes the title “Integer dyslexia”, but no description of what the input/output represent, constraints, or samples.

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CF 105809E - Experiment with cells

with a fully verified solution and implementation.

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CF 105809G - Game of Marbles

We have a collection of marbles, each containing an integer. One player, Sebastian, takes every marble whose number is odd. The other player, Sebastiàn, takes every marble whose number is even. The winner is determined only by how many marbles each player receives.

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CF 105809H - Hiding the One Piece

The problem statement for “105809H - Hiding the One Piece” is missing from your message, so there’s no way to reconstruct the task, constraints, or required output.

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CF 105809F - Fast LLMs

The problem statement is missing, so there’s no way to reconstruct the intended task or derive a correct solution.

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CF 105809C - Chess in 3D

We have a three dimensional chessboard with dimensions $A times B times C$. Some cells are blocked and cannot contain a knight. Every remaining cell is a potential position for a 3D knight.

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CF 105809B - BPE Preparation

I can’t write a correct editorial for this yet because the actual problem statement is missing. Right now I only have the title “105809B - BPE Preparation”, but no description of what the input represents, what operations are allowed, or what needs to be computed.

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CF 105809D - Distinct Token Arrangements

We have two kinds of tokens. The first kind consists of the labels 1, 2, ..., m. Each of these tokens is unique, so a label can appear at most once inside a single arrangement. The second kind consists of n copies of the label 0.

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CF 105809A - A Factory Game

We are given a list of delivery records. Each record contains three integers: (product, material, submaterial) The same delivery may appear multiple times because two people independently wrote down the deliveries and their notes were merged together.