Codeforces Round 1028 (Div. 1)

Solutions for Codeforces Round 1028 (Div. 1) (contest 2115). 3/7 problems verified against sample I/O. Difficulty range: 1500-3500.

7 items

Codeforces Round 1028 (Div. 1)

Type: Div. 1 | Problems: 7 | Verified: 3/7 | Rating range: 1500-3500 | Time: 12m 1s

Problem Name Rating Tags Solve Time Verified
A Gellyfish and Flaming Peony 1500 constructive-algorithms, dp, math 1m 17s ✓
B Gellyfish and Camellia Japonica 2100 brute-force, constructive-algorithms, dfs-and-similar 1m 56s ✗
C Gellyfish and Eternal Violet 2700 combinatorics, dp, greedy 1m 48s ✗
D Gellyfish and Forget-Me-Not 2900 bitmasks, dp, games 3m 4s ✗
E Gellyfish and Mayflower 3500 dp, graphs 49s ✓
F1 Gellyfish and Lycoris Radiata (Easy Version) 3500 data-structures 1m 7s ✓
F2 Gellyfish and Lycoris Radiata (Hard Version) 3500 data-structures 2m ✗
Practice › Codeforces Solutions › Codeforces Round 1028 (Div. 1) ›

CF 2115F2 - Gellyfish and Lycoris Radiata (Hard Version)

We are asked to maintain an array of sets, starting empty, under three types of modification operations: inserting the current operation index into a prefix of sets, reversing a prefix of sets, and deleting a given element from all sets.
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CF 2115D - Gellyfish and Forget-Me-Not

For two odd-index cells $A(x1,y1)$, $B(x2,y2)$, we need to count the number of cells $C$ such that: - $C$ is adjacent to $A$ - $C$ is adjacent to $B$ - and $A ne B ne C$ On a grid, this intersection has a known structure: - If $A$ and $B$ differ by 2 in one coordinate and 0 in…
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CF 2115B - Gellyfish and Camellia Japonica

We are given a final array b that results from a sequence of q operations on an initial array a. Each operation selects two positions x and y, takes the minimum of their current values, and assigns it to a third position z.
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CF 2115C - Gellyfish and Eternal Violet

We are given a group of monsters, each starting with some integer health value. Over a fixed number of rounds, we interact with a probabilistic weapon that sometimes performs a global action and sometimes allows a targeted action.
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CF 2115F1 - Gellyfish and Lycoris Radiata (Easy Version)

We are asked to maintain an array of n sets under a sequence of q online operations, where each operation modifies some prefix of sets or deletes a specific element from all sets, and then asks for the smallest element in a particular set.
codeforces competitive-programming data-structures Jun 8, 2026
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CF 2115E - Gellyfish and Mayflower

We are asked to navigate a directed acyclic graph (DAG) with vertices numbered from 1 to n. Each vertex contains a trader who sells cards with a given power for a given cost.
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CF 2115A - Gellyfish and Flaming Peony

We start with a sequence of positive integers. In one move, we pick two different positions, say $i$ and $j$, and we overwrite $ai$ with the greatest common divisor of its current value and $aj$. The second element $aj$ stays unchanged.
codeforces competitive-programming constructive-algorithms dp math number-theory Jun 8, 2026