Codeforces Round 553 (Div. 2)

Solutions for Codeforces Round 553 (Div. 2) (contest 1151). 5/6 problems verified against sample I/O. Difficulty range: 1000-2300.

6 items

Codeforces Round 553 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 5/6 | Rating range: 1000-2300 | Time: 12m 3s

Problem Name Rating Tags Solve Time Verified
A Maxim and Biology 1000 brute-force, strings 1m 38s ✓
B Dima and a Bad XOR 1600 bitmasks, brute-force, constructive-algorithms 1m 41s ✓
C Problem for Nazar 1800 constructive-algorithms, math 1m 41s ✓
D Stas and the Queue at the Buffet 1600 greedy, math, sortings 3m 3s ✓
E Number of Components 2100 combinatorics, data-structures, dp 2m 2s ✓
F Sonya and Informatics 2300 combinatorics, dp, matrices 1m 58s ✗
Practice › Codeforces Solutions › Codeforces Round 553 (Div. 2) ›

CF 1151D - Stas and the Queue at the Buffet

We have a queue of students, each with two personal characteristics: $ai$, which measures how much they dislike people in front of them, and $bi$, which measures how much they dislike people behind them.
codeforces competitive-programming greedy math sortings Jun 12, 2026
Practice › Codeforces Solutions › Codeforces Round 553 (Div. 2) ›

CF 1151E - Number of Components

We are given a tree of n vertices arranged in a simple line, where each vertex has a value ai. Conceptually, this is just an array of numbers connected consecutively by edges.
codeforces competitive-programming combinatorics data-structures dp math Jun 12, 2026
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CF 1151F - Sonya and Informatics

We are asked to determine the probability that an array consisting of zeros and ones becomes sorted in non-decreasing order after performing a fixed number of random swaps. Each swap selects two distinct positions in the array uniformly at random and exchanges their values.
codeforces competitive-programming combinatorics dp matrices probabilities Jun 12, 2026
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CF 1151B - Dima and a Bad XOR

We are given a grid of integers where each row represents a set of choices, and from every row we must pick exactly one number. After picking one number per row, we compute the bitwise XOR of all chosen numbers.
codeforces competitive-programming bitmasks brute-force constructive-algorithms dp Jun 12, 2026
Practice › Codeforces Solutions › Codeforces Round 553 (Div. 2) ›

CF 1151C - Problem for Nazar

The process generates a single infinite sequence by repeatedly appending blocks of numbers, where each block alternates between odd and even numbers and doubles in size each time.
codeforces competitive-programming constructive-algorithms math Jun 12, 2026
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CF 1151A - Maxim and Biology

We are given a string of uppercase Latin letters of length at least 4, and we want to transform some of its letters so that the substring "ACTG" appears somewhere.
codeforces competitive-programming brute-force strings Jun 12, 2026