Codeforces Round 766 (Div. 2)

Solutions for Codeforces Round 766 (Div. 2) (contest 1627). 4/6 problems verified against sample I/O. Difficulty range: 800-2700.

6 items

Codeforces Round 766 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 4/6 | Rating range: 800-2700 | Time: 13m 39s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Not Shading	800	constructive-algorithms, implementation	1m 35s	✓
B	Not Sitting	1300	games, greedy, sortings	1m 32s	✓
C	Not Assigning	1400	constructive-algorithms, dfs-and-similar, number-theory	1m 37s	✓
D	Not Adding	1900	brute-force, dp, math	1m 20s	✓
E	Not Escaping	2200	data-structures, dp, implementation	1m 57s	✗
F	Not Splitting	2700	geometry, graphs, greedy	5m 38s	✗

Practice › Codeforces Solutions › Codeforces Round 766 (Div. 2) ›

CF 1627F - Not Splitting

The original algorithm I suggested XORs all cells (i+j)%2==0 excluding the bottom-right diagonal. This produces the wrong result because it is misapplying the standard trick for this problem. The correct approach comes from observing the XOR-sum properties: 1.

Practice › Codeforces Solutions › Codeforces Round 766 (Div. 2) ›

CF 1627E - Not Escaping

The building can be viewed as a layered grid where each floor is a row of rooms. Moving horizontally inside a floor has a cost proportional to how far you walk and a floor-specific penalty factor, while moving vertically is only possible through directed ladders that may also…

Practice › Codeforces Solutions › Codeforces Round 766 (Div. 2) ›

CF 1627D - Not Adding

We are given an array of distinct integers, and we can repeatedly add new elements to it. Specifically, we can select any two elements, compute their greatest common divisor (GCD), and append it to the array if that GCD is not already present.

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CF 1627C - Not Assigning

We are given a multiset of values that form a cyclic array. The task is not to keep this array fixed, but to consider all distinct permutations of its elements arranged on a circle.

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CF 1627A - Not Shading

We are given a small grid of size up to 50 by 50, where each cell is either black or white. From any black cell, we are allowed to perform an operation that spreads blackness in a very specific way: we pick one black cell and either paint its entire row black or paint its…

Practice › Codeforces Solutions › Codeforces Round 766 (Div. 2) ›

CF 1627B - Not Sitting

We are given a classroom represented as a grid with $n$ rows and $m$ columns. Each cell is a seat. Tina can paint exactly $k$ seats pink, where $k$ ranges from 0 to $n cdot m - 1$. Rahul then chooses a seat avoiding painted seats, aiming to sit as close as possible to Tina.