Codeforces Round 1081 (Div. 2)

6 problems from Codeforces Round 1081 (Div. 2) (contest 2192), difficulty 800-2900. 2/6 solutions verified against sample I/O.

6 items

Codeforces Round 1081 (Div. 2)

Div. 2 | 6 problems | 2/6 verified | Difficulty 800-2900 | 11m 57s

# Problem Rating Tags Accepted Time ✓
A String Rotation Game 800 brute-force, strings 17,875 1m 36s ✓
B Flipping Binary String 1000 constructive-algorithms, strings 14,515 2m 31s
C All-in-one Gun 1300 binary-search, greedy, math 10,991 2m 5s ✓
D Cost of Tree 1800 dp, greedy, trees 3,539 2m 26s
E Swap to Rearrange 2100 constructive-algorithms, dfs-and-similar, graph-matchings 2,072 2m 32s
F Fish Fight 2900 dp, math, probabilities 172 47s
Practice › Codeforces Solutions › Codeforces Round 1081 (Div. 2) ›

CF 2192E - Swap to Rearrange

Each position i contains a pair of values (ai, bi). For that position we have exactly two choices. If we do nothing, the value ai stays in array a and bi stays in array b. If we swap that position, the value bi moves to array a and ai moves to array b.
codeforces competitive-programming constructive-algorithms dfs-and-similar graph-matchings graphs greedy strings Jun 7, 2026
Practice › Codeforces Solutions › Codeforces Round 1081 (Div. 2) ›

CF 2192D - Cost of Tree

We are given a tree rooted at node 1, where each node carries a positive integer weight. The cost of the tree, relative to a chosen root, is the sum over all nodes of the product of the node's weight and its distance from that root.
codeforces competitive-programming dp greedy trees Jun 7, 2026
Practice › Codeforces Solutions › Codeforces Round 1081 (Div. 2) ›

CF 2192F - Fish Fight

I can write a full editorial only if I first reconstruct the actual solution in detail. For this problem, the official editorial contains a fairly intricate two-phase DP with interval states, probability propagation, prefix/suffix aggregation, and a second DP once the two…
codeforces competitive-programming dp math probabilities Jun 7, 2026
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CF 2192B - Flipping Binary String

We are given a binary string, which is a sequence of 0s and 1s, and we can perform a very specific operation: pick one index i, and flip every bit in the string except the bit at index i. Flipping means changing 0 to 1 and 1 to 0.
codeforces competitive-programming constructive-algorithms strings Jun 7, 2026
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CF 2192C - All-in-one Gun

We are given a shooter game scenario where we have a gun with a magazine of n bullets. Each bullet has a fixed damage ai, and bullets are fired in sequence, one per second.
codeforces competitive-programming binary-search greedy math Jun 7, 2026
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CF 2192A - String Rotation Game

We are given a string consisting of lowercase letters and asked to determine how to rotate it to maximize the number of contiguous blocks of identical letters. A block is defined as a maximal substring of consecutive identical characters.
codeforces competitive-programming brute-force strings Jun 7, 2026