Codeforces Round 903 (Div. 3)

Solutions for Codeforces Round 903 (Div. 3) (contest 1881). 5/7 problems verified against sample I/O. Difficulty range: 800-2000.

7 items

Codeforces Round 903 (Div. 3)

Type: Div. 3 | Problems: 7 | Verified: 5/7 | Rating range: 800-2000 | Time: 13m

Problem Name Rating Tags Solve Time Verified
A Don't Try to Count 800 brute-force, strings 1m 52s ✓
B Three Threadlets 900 math 1m 27s ✓
C Perfect Square 1200 brute-force, implementation 1m 53s ✓
D Divide and Equalize 1300 math, number-theory 1m 10s ✓
E Block Sequence 1500 dp 2m 4s ✗
F Minimum Maximum Distance 1700 dfs-and-similar, dp, graphs 2m 20s ✓
G Anya and the Mysterious String 2000 binary-search, data-structures 2m 14s ✗
Practice › Codeforces Solutions › Codeforces Round 903 (Div. 3) ›

CF 1881G - Anya and the Mysterious String

We are given a string that is continuously modified and queried. Each modification shifts all characters in a segment forward in the alphabet cyclically, like a Caesar shift applied to a range. After each update, we must answer whether a chosen substring is “valid”.
codeforces competitive-programming binary-search data-structures Jun 8, 2026
Practice › Codeforces Solutions › Codeforces Round 903 (Div. 3) ›

CF 1881F - Minimum Maximum Distance

We are given a tree and a subset of its vertices marked as special. For every vertex $v$, define $f(v)$ as the distance from $v$ to the farthest marked vertex. We want to choose a vertex whose farthest marked vertex is as close as possible.
codeforces competitive-programming dfs-and-similar dp graphs shortest-paths trees Jun 8, 2026
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CF 1881E - Block Sequence

We are given a sequence of integers, and our goal is to transform it into a "beautiful" sequence using the minimum number of deletions.
codeforces competitive-programming dp Jun 8, 2026
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CF 1881D - Divide and Equalize

We are given several independent test cases. In each test case, we start with an array of positive integers. We are allowed to repeatedly pick two different positions and move a multiplicative factor from one value to the other, but the factor must be a divisor of the first…
codeforces competitive-programming math number-theory Jun 8, 2026
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CF 1881A - Don't Try to Count

We start with a string x. One operation replaces x with x + x, meaning the current string is appended to itself and its length doubles. We are also given a target string s.
codeforces competitive-programming brute-force strings Jun 8, 2026
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CF 1881C - Perfect Square

We are given an $n times n$ matrix of lowercase letters, where $n$ is even. The goal is to transform the matrix into a "perfect square," which is defined as a matrix that remains unchanged when rotated $90^circ$ clockwise.
codeforces competitive-programming brute-force implementation Jun 8, 2026
Practice › Codeforces Solutions › Codeforces Round 903 (Div. 3) ›

CF 1881B - Three Threadlets

We are given three positive integers, each representing the length of a thread. In one move, we pick a single thread and split it into two smaller threads with integer lengths, both strictly positive, and their sum equal to the original length.
codeforces competitive-programming math Jun 8, 2026