Codeforces Round 771 (Div. 2)

Solutions for Codeforces Round 771 (Div. 2) (contest 1638). 2/6 problems verified against sample I/O. Difficulty range: 800-3200.

6 items

Codeforces Round 771 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 2/6 | Rating range: 800-3200 | Time: 10m 2s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Reverse	800	constructive-algorithms, greedy, math	1m 32s	✗
B	Odd Swap Sort	1100	data-structures, math, sortings	2m 38s	✗
C	Inversion Graph	1300	data-structures, dsu, graphs	1m 11s	✓
D	Big Brush	2000	constructive-algorithms, data-structures, greedy	1m 41s	✗
E	Colorful Operations	2400	brute-force, data-structures, implementation	1m 21s	✓
F	Two Posters	3200	brute-force, data-structures, greedy	1m 39s	✗

Practice › Codeforces Solutions › Codeforces Round 771 (Div. 2) ›

CF 1638F - Two Posters

We are given a sequence of vertical panels, each panel having width one and a fixed height. Visually, each panel is attached to a horizontal bar at the top, and can be shifted upward or downward, but it must always remain connected to that bar, meaning every panel remains a…

Practice › Codeforces Solutions › Codeforces Round 771 (Div. 2) ›

CF 1638E - Colorful Operations

We are maintaining a length-n array that starts completely uniform: every position holds value 0 and belongs to color 1. Over time, the array evolves through two kinds of updates. One type recolors a whole interval, replacing whatever colors were there with a new one.

Practice › Codeforces Solutions › Codeforces Round 771 (Div. 2) ›

CF 1638D - Big Brush

We are given a painted canvas represented as a grid with n rows and m columns. Each cell in this grid contains a color, and the painting process was performed using only a 2 × 2 brush.

Practice › Codeforces Solutions › Codeforces Round 771 (Div. 2) ›

CF 1638B - Odd Swap Sort

This problem is rated 3500 and its solution relies on a fairly deep structural characterization of graphs whose cycle space admits a consistent cyclic orientation.

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CF 1638A - Reverse

We are given a permutation of length $n$, which is an array containing all integers from $1$ to $n$ exactly once. We are allowed to choose exactly one contiguous subsegment of the permutation and reverse it.

Practice › Codeforces Solutions › Codeforces Round 771 (Div. 2) ›

CF 1638C - Inversion Graph

We are given a permutation of size $n$, which is an array containing all integers from 1 to $n$ exactly once in some order. From this permutation, we construct an undirected graph on $n$ vertices, where each vertex corresponds to a position in the permutation.