Codeforces Round 580 (Div. 1)

Solutions for Codeforces Round 580 (Div. 1) (contest 1205). 2/6 problems verified against sample I/O. Difficulty range: 1200-3400.

6 items

Codeforces Round 580 (Div. 1)

Type: Div. 1 | Problems: 6 | Verified: 2/6 | Rating range: 1200-3400 | Time: 28m 3s

Problem Name Rating Tags Solve Time Verified
A Almost Equal 1200 constructive-algorithms, greedy, math 5m 8s ✗
B Shortest Cycle 1900 bitmasks, brute-force, graphs 1m 41s ✓
C Palindromic Paths 2400 implementation, interactive 5m 3s ✗
D Almost All 2700 constructive-algorithms, trees 4m 42s ✗
E Expected Value Again 3100 combinatorics, strings 2m 22s ✓
F Beauty of a Permutation 3400 constructive-algorithms, math 9m 7s ✗
Practice › Codeforces Solutions › Codeforces Round 580 (Div. 1) ›

CF 1205F - Beauty of a Permutation

We are asked to build permutations of numbers from 1 to n such that a specific structural property holds on subarrays, and to control how many subarrays satisfy it.
codeforces competitive-programming constructive-algorithms math Jun 13, 2026
Practice › Codeforces Solutions › Codeforces Round 580 (Div. 1) ›

CF 1205A - Almost Equal

We are asked to arrange the numbers from 1 to 2n around a circle. Once the circle is fixed, we look at every contiguous block of exactly n elements. Each such block produces a sum, and since the circle has 2n positions, there are 2n such blocks (wrapping around at the end).
codeforces competitive-programming constructive-algorithms greedy math Jun 13, 2026
Practice › Codeforces Solutions › Codeforces Round 580 (Div. 1) ›

CF 1205C - Palindromic Paths

We are given an unknown binary grid of size $n times n$, where $n$ is odd. Each cell contains either 0 or 1. Two facts are guaranteed: the top-left cell is 1 and the bottom-right cell is 0. We cannot directly read the grid.
codeforces competitive-programming implementation interactive Jun 13, 2026
Practice › Codeforces Solutions › Codeforces Round 580 (Div. 1) ›

CF 1205D - Almost All

We are given a tree with $n$ nodes. Each edge must be assigned a non-negative integer. Once the edges are labeled, every pair of nodes defines a path, and each path has a sum obtained by adding the values on its edges.
codeforces competitive-programming constructive-algorithms trees Jun 13, 2026
Practice › Codeforces Solutions › Codeforces Round 580 (Div. 1) ›

CF 1205E - Expected Value Again

We are looking at strings of length $n$ built from an alphabet of size $k$, chosen uniformly at random. For any fixed string, we examine how many of its prefixes also appear as suffixes of the same length.
codeforces competitive-programming combinatorics strings Jun 11, 2026
Practice › Codeforces Solutions › Codeforces Round 580 (Div. 1) ›

CF 1205B - Shortest Cycle

We are given a collection of integers, and we interpret each integer as a node in a graph. Two nodes are connected when their bitwise AND is non-zero, meaning they share at least one common bit set to 1.
codeforces competitive-programming bitmasks brute-force graphs shortest-paths Jun 11, 2026