Codeforces Round 889 (Div. 1)

Solutions for Codeforces Round 889 (Div. 1) (contest 1854). 2/7 problems verified against sample I/O. Difficulty range: 1400-3500.

7 items

Codeforces Round 889 (Div. 1)

Type: Div. 1 | Problems: 7 | Verified: 2/7 | Rating range: 1400-3500 | Time: 12m 23s

Problem Name Rating Tags Solve Time Verified
A1 Dual (Easy Version) 1400 constructive-algorithms, math 2m 33s ✗
A2 Dual (Hard Version) 1900 constructive-algorithms, math 2m 44s ✗
B Earn or Unlock 2200 bitmasks, brute-force, dp 52s ✓
C Expected Destruction 2500 combinatorics, dp, math 1m 55s ✗
D Michael and Hotel 3000 binary-search, interactive, trees 1m 38s ✗
E Game Bundles 3000 brute-force, constructive-algorithms, dp 1m 25s ✗
F Mark and Spaceship 3500 brute-force, dp 1m 16s ✓
Practice › Codeforces Solutions › Codeforces Round 889 (Div. 1) ›

CF 1854D - Michael and Hotel

We are given a directed graph on $n le 500$ vertices where each vertex has exactly one outgoing edge. From every room $i$, a teleporter sends us deterministically to room $ai$.
codeforces competitive-programming binary-search interactive trees Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 889 (Div. 1) ›

CF 1854E - Game Bundles

We are asked to select a collection of games, each with a positive enjoyment value, such that the number of distinct subsets of these games that sum to exactly 60 equals a given integer $m$.
codeforces competitive-programming brute-force constructive-algorithms dp greedy math Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 889 (Div. 1) ›

CF 1854F - Mark and Spaceship

We are working in a four-dimensional integer grid. From the origin, a spaceship executes a sequence of moves, where each move chooses one of the four coordinate axes and steps by one unit in either direction.
codeforces competitive-programming brute-force dp Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 889 (Div. 1) ›

CF 1854C - Expected Destruction

We are given a set of distinct integers S drawn from the range 1 to m. Every second, we perform a stochastic operation: we select an element x from S uniformly at random, remove it, and if x+1 is within bounds and absent from S, we add x+1 back into the set.
codeforces competitive-programming combinatorics dp math probabilities Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 889 (Div. 1) ›

CF 1854A2 - Dual (Hard Version)

We are given an integer array. In one operation we choose two positions i and j and add the value at position j into position i. The goal is not to sort the array. We only need the final array to be non-decreasing, meaning every element is at least as large as the previous one.
codeforces competitive-programming constructive-algorithms math Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 889 (Div. 1) ›

CF 1854A1 - Dual (Easy Version)

We are given an array of integers that may be positive, negative, or zero. We are allowed to perform operations where we pick any two indices $i$ and $j$ and add the value of $aj$ to $ai$.
codeforces competitive-programming constructive-algorithms math Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 889 (Div. 1) ›

CF 1854B - Earn or Unlock

We are given a scenario where a player wants to maximize their earnings while unlocking skills in a game. There are n skills, each requiring certain previously unlocked skills and providing a coin reward if unlocked.
codeforces competitive-programming bitmasks brute-force dp Jun 9, 2026