Codeforces Round 581 (Div. 2)

Solutions for Codeforces Round 581 (Div. 2) (contest 1204). 4/6 problems verified against sample I/O. Difficulty range: 900-2300.

6 items

Codeforces Round 581 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 4/6 | Rating range: 900-2300 | Time: 22m 43s

Problem Name Rating Tags Solve Time Verified
A BowWow and the Timetable 1000 math 1m 55s ✓
B Mislove Has Lost an Array 900 greedy, math 2m 53s ✓
C Anna, Svyatoslav and Maps 1700 dp, graphs, greedy 1m 44s ✓
D1 Kirk and a Binary String (easy version) 2000 brute-force, greedy, strings 3m 44s ✗
D2 Kirk and a Binary String (hard version) 2100 data-structures, greedy, math 4m 40s ✓
E Natasha, Sasha and the Prefix Sums 2300 combinatorics, dp, math 7m 47s ✗
Practice › Codeforces Solutions › Codeforces Round 581 (Div. 2) ›

CF 1204E - Natasha, Sasha and the Prefix Sums

We are looking at all possible sequences of length $n+m$ made of exactly $n$ ones and $m$ minus ones. Every arrangement is considered once, so this is a multiset permutation problem.
codeforces competitive-programming combinatorics dp math number-theory Jun 13, 2026
Practice › Codeforces Solutions › Codeforces Round 581 (Div. 2) ›

CF 1204D2 - Kirk and a Binary String (hard version)

We are given a binary string and we are allowed to construct another binary string of the same length. The requirement is not local, it is global over all substrings: for every interval of positions, the value of the longest non-decreasing subsequence inside that interval must…
codeforces competitive-programming data-structures greedy math strings Jun 13, 2026
Practice › Codeforces Solutions › Codeforces Round 581 (Div. 2) ›

CF 1204D1 - Kirk and a Binary String (easy version)

We are given a binary string and asked to construct another binary string of the same length. The key requirement is not about matching the strings themselves, but about preserving a structural value computed on every substring: the length of the longest non-decreasing…
codeforces competitive-programming brute-force greedy strings Jun 13, 2026
Practice › Codeforces Solutions › Codeforces Round 581 (Div. 2) ›

CF 1204B - Mislove Has Lost an Array

We are given a length n array of positive integers, but the array is not arbitrary. Every value in it must satisfy a strict structural rule: each number is either 1, or it is an even number whose half is also present somewhere in the array.
codeforces competitive-programming greedy math Jun 13, 2026
Practice › Codeforces Solutions › Codeforces Round 581 (Div. 2) ›

CF 1204A - BowWow and the Timetable

The trains leave at times $$1, 4, 16, 64, dots$$ which are exactly the powers of 4. Given a time $s$, we need to count how many of these departure times are strictly smaller than $s$. The unusual part is that $s$ is not given in decimal.
codeforces competitive-programming math Jun 11, 2026
Practice › Codeforces Solutions › Codeforces Round 581 (Div. 2) ›

CF 1204C - Anna, Svyatoslav and Maps

We are given a directed graph represented as an adjacency matrix, where each vertex has edges to other vertices, but no vertex has a loop to itself. Along with the graph, we are also given a path p as a sequence of vertex indices.
codeforces competitive-programming dp graphs greedy shortest-paths Jun 11, 2026