Codeforces Round 901 (Div. 1)

Solutions for Codeforces Round 901 (Div. 1) (contest 1874). 3/7 problems verified against sample I/O. Difficulty range: 1200-3500.

7 items

Codeforces Round 901 (Div. 1)

Type: Div. 1 | Problems: 7 | Verified: 3/7 | Rating range: 1200-3500 | Time: 15m 25s

Problem Name Rating Tags Solve Time Verified
A Jellyfish and Game 1200 brute-force, games, greedy 1m 59s ✓
B Jellyfish and Math 2400 bitmasks, brute-force, dfs-and-similar 2m 26s ✓
C Jellyfish and EVA 2300 dp, graphs, greedy 1m 57s ✗
D Jellyfish and Miku 2800 divide-and-conquer, dp, math 2m 27s ✗
E Jellyfish and Hack 3000 dp, math 1m 55s ✗
F Jellyfish and OEIS 3500 dp 2m 34s ✗
G Jellyfish and Inscryption 3500 dp 2m 7s ✓
Practice › Codeforces Solutions › Codeforces Round 901 (Div. 1) ›

CF 1874G - Jellyfish and Inscryption

We are asked to navigate a directed acyclic graph (DAG) from vertex 1 to vertex n, collecting cards and props along the way, and then maximize our total “power” at the end. Cards have both HP and damage, and their power is the product of the two.
codeforces competitive-programming dp Jun 8, 2026
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CF 1874F - Jellyfish and OEIS

We are asked to count permutations of numbers from 1 to n that avoid certain ordered subarrays. More concretely, for each index l, we are given a number ml, and any contiguous segment starting at l and ending at r ≤ ml must not be a consecutive permutation of [l, l+1, ..., r].
codeforces competitive-programming dp Jun 8, 2026
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CF 1874D - Jellyfish and Miku

We have a simple linear chain of cities numbered from 0 to n, connected sequentially by n roads. Each road has a "beauty" value, which determines the probability that Jellyfish will traverse it if she stands at one of its endpoints.
codeforces competitive-programming divide-and-conquer dp math probabilities Jun 8, 2026
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CF 1874E - Jellyfish and Hack

We are asked to analyze a variant of quicksort where the first element is always chosen as the pivot. For any array, the "time" the function takes is defined recursively as the size of the array plus the time taken by the recursive calls on elements smaller and larger than the…
codeforces competitive-programming dp math Jun 8, 2026
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CF 1874B - Jellyfish and Math

We are asked to transform a pair of non-negative integers (x, y) from an initial state (a, b) to a target state (c, d) using a small set of bitwise operations. The operations available are x := x & y, x := x The constraints are significant.
codeforces competitive-programming bitmasks brute-force dfs-and-similar dp graphs shortest-paths Jun 8, 2026
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CF 1874A - Jellyfish and Game

We have two players, Jellyfish and Gellyfish, each with a collection of green apples. Jellyfish has n apples with values stored in array a, and Gellyfish has m apples with values stored in array b. They play a game for k rounds.
codeforces competitive-programming brute-force games greedy implementation Jun 8, 2026
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CF 1874C - Jellyfish and EVA

We are given a directed acyclic graph in a very specific form: every edge goes from a smaller numbered city to a larger numbered city. This means the graph is already topologically sorted by vertex index. We start at city 1 and want to reach city n.
codeforces competitive-programming dp graphs greedy math probabilities Jun 8, 2026