Codeforces Round 131 (Div. 1)

Solutions for Codeforces Round 131 (Div. 1) (contest 213). 3/5 problems verified against sample I/O. Difficulty range: 1700-2700.

5 items

Codeforces Round 131 (Div. 1)

Type: Div. 1 | Problems: 5 | Verified: 3/5 | Rating range: 1700-2700 | Time: 7m 23s

Problem Name Rating Tags Solve Time Verified
A Game 1700 dfs-and-similar, greedy 52s ✓
B Numbers 1900 combinatorics, dp 54s ✗
C Relay Race 2000 dp 2m 58s ✓
D Stars 2300 constructive-algorithms, geometry 1m 36s ✗
E Two Permutations 2700 data-structures, hashing, strings 1m 3s ✓
Practice › Codeforces Solutions › Codeforces Round 131 (Div. 1) ›

CF 213A - Game

We are given a game split into n parts. Each part must be completed on a specific computer, and some parts depend on others, forming a dependency graph without cycles. Rubik can start at any computer and spends exactly one hour to complete a part.
codeforces competitive-programming dfs-and-similar greedy May 29, 2026
Practice › Codeforces Solutions › Codeforces Round 131 (Div. 1) ›

CF 213B - Numbers

This is a Type A, “Find all X” problem. A complete solution must do two things: First, it must show that every listed family of solutions actually satisfies the system. Second, it must prove that no other solutions exist. The proposed proof does both parts.
codeforces competitive-programming combinatorics dp May 29, 2026
Practice › Codeforces Solutions › Codeforces Round 131 (Div. 1) ›

CF 213C - Relay Race

We are given an n×n grid where each cell contains an integer, which can be positive or negative. Furik starts at the top-left corner (1,1) and moves only right or down, while Rubik starts at the bottom-right corner (n,n) and moves only left or up.
codeforces competitive-programming dp May 29, 2026
Practice › Codeforces Solutions › Codeforces Round 131 (Div. 1) ›

CF 213D - Stars

We must construct n pentagram-shaped stars in the plane. Each star comes from a regular pentagon with side length 10, and the painted segments are exactly its five diagonals. The output is not just geometry. We also need a valid drawing order.
codeforces competitive-programming constructive-algorithms geometry May 29, 2026
Practice › Codeforces Solutions › Codeforces Round 131 (Div. 1) ›

CF 213E - Two Permutations

We are given two permutations, one of length n and another of length m (n ≤ m). A permutation is a sequence containing all numbers from 1 to its length exactly once.
codeforces competitive-programming data-structures hashing strings May 29, 2026