Codeforces Round 1091 (Div. 2) and CodeCraft 26

8 problems from Codeforces Round 1091 (Div. 2) and CodeCraft 26 (contest 2217), difficulty 800-2800. 0/8 solutions verified against sample I/O.

8 items

Codeforces Round 1091 (Div. 2) and CodeCraft 26

Div. 2 | 8 problems | 0/8 verified | Difficulty 800-2800 | 14m 29s

# Problem Rating Tags Accepted Time ✓
A The Equalizer 800 math 21,629 1m 40s
B Flip the Bit (Easy Version) 1000 greedy, implementation 15,960 1m 42s
C Grid Covering 1300 chinese-remainder-theorem, math, number-theory 10,362 1m 40s
D Flip the Bit (Hard Version) 1900 greedy, implementation, math 3,312 2m
E Definitely Larger 2000 binary-search, constructive-algorithms, data-structures 2,051 1m 44s
F Interval Game 2300 bitmasks, combinatorics, constructive-algorithms 691 1m 56s
G Down the Pivot 2600 combinatorics, dp, math 344 1m 46s
H Closer 2800 dfs-and-similar, dp, trees 200 2m 1s
Practice › Codeforces Solutions › Codeforces Round 1091 (Div. 2) and CodeCraft 26 ›

CF 2217H - Closer

We have a tree with $2n$ vertices, each hosting a single person. Every person carries a badge corresponding to one of $n$ deals, and each deal appears exactly twice among the people.
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CF 2217G - Down the Pivot

We are asked to count labeled binary trees with a very specific operation and cost function. Each node of the tree is labeled either 0 or 1. The allowed operation is to pick a simple path that passes through the root and flip every label along that path.
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CF 2217D - Flip the Bit (Hard Version)

We are given a binary array and a set of special indices where all values are identical. Our goal is to make the entire array equal to the value at these special indices using the fewest number of flip operations.
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CF 2217F - Interval Game

The problem describes a two-player turn-based game involving two intervals. Alice chooses the first interval within a fixed bound [1, x1], and the second interval is picked uniformly at random from all valid intervals in [1, x2].
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CF 2217E - Definitely Larger

We are given a fixed permutation p of size n. Think of each position i as a point that has two independent labels: its position index and its value pi.
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CF 2217B - Flip the Bit (Easy Version)

We are given a binary array of length $n$ and a single special index $p1$ (since $k=1$). The element at this special index has value $x$, and our goal is to make the entire array equal to $x$.
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CF 2217A - The Equalizer

We are given an array of positive integers. Two players alternate turns starting with Shaunak. A normal turn consists of picking any position whose value is still positive and decreasing it by one.
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CF 2217C - Grid Covering

The problem asks whether a person starting at the top-left corner of a grid can eventually visit every cell by jumping in a very specific pattern.
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