Codeforces Round 876 (Div. 2)

Solutions for Codeforces Round 876 (Div. 2) (contest 1839). 0/5 problems verified against sample I/O. Difficulty range: 800-2400.

5 items

Codeforces Round 876 (Div. 2)

Type: Div. 2 | Problems: 5 | Verified: 0/5 | Rating range: 800-2400 | Time: 10m 32s

Problem Name Rating Tags Solve Time Verified
A The Good Array 800 greedy, implementation, math 4m 4s ✗
B Lamps 1100 greedy, sortings 1m 41s ✗
C Insert Zero and Invert Prefix 1300 constructive-algorithms 1m 25s ✗
D Ball Sorting 2100 data-structures, dp, sortings 2m 3s ✗
E Decreasing Game 2400 constructive-algorithms, dfs-and-similar, dp 1m 19s ✗
Practice › Codeforces Solutions › Codeforces Round 876 (Div. 2) ›

CF 1839A - The Good Array

The problem asks for the smallest number of ones needed in a binary array of length $n$ to satisfy a set of prefix and suffix constraints.
codeforces competitive-programming greedy implementation math Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 876 (Div. 2) ›

CF 1839D - Ball Sorting

We are given a sequence of n balls, each painted a distinct color from 1 to n. The initial sequence may be completely scrambled. Our goal is to rearrange the balls so that the ball at position i has color i.
codeforces competitive-programming data-structures dp sortings Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 876 (Div. 2) ›

CF 1839E - Decreasing Game

We are playing a two-person game on an array of positive integers. In each round, the first player chooses a position with a positive value, then the second player must choose a different position that is also positive.
codeforces competitive-programming constructive-algorithms dfs-and-similar dp greedy interactive Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 876 (Div. 2) ›

CF 1839B - Lamps

We are given a collection of lamps, each with two properties: ai and bi. Initially, all lamps are off. You can turn on a lamp that is off to earn bi points.
codeforces competitive-programming greedy sortings Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 876 (Div. 2) ›

CF 1839C - Insert Zero and Invert Prefix

We are asked to construct a binary sequence step by step using a sequence of operations. We start with an empty sequence b and, in each of the n operations, we insert a zero somewhere in b and invert all elements before that position.
codeforces competitive-programming constructive-algorithms Jun 9, 2026