Codeforces Round 948 (Div. 2)

Solutions for Codeforces Round 948 (Div. 2) (contest 1977). 3/5 problems verified against sample I/O. Difficulty range: 800-2600.

5 items

Codeforces Round 948 (Div. 2)

Type: Div. 2 | Problems: 5 | Verified: 3/5 | Rating range: 800-2600 | Time: 10m 26s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Little Nikita	800	math	1m 32s	✓
B	Binary Colouring	1100	bitmasks, constructive-algorithms, greedy	2m 12s	✓
C	Nikita and LCM	1900	brute-force, data-structures, dp	2m 32s	✓
D	XORificator	2300	bitmasks, brute-force, greedy	2m 8s	✗
E	Tensor	2600	constructive-algorithms, graphs, interactive	2m 2s	✗

Practice › Codeforces Solutions › Codeforces Round 948 (Div. 2) ›

CF 1977E - Tensor

We are given an interactive problem where there is a hidden directed graph with $n$ vertices, numbered from $1$ to $n$. Each edge in the graph goes "backwards," meaning it connects a higher-numbered vertex $j$ to a lower-numbered vertex $i$ ($i < j$).

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CF 1977D - XORificator

We are given a matrix of size $n times m$ consisting only of 0s and 1s. We can “flip” any row using a XORificator, which changes every 0 to 1 and every 1 to 0 in that row. After performing any flips, we want to maximize the number of columns that contain exactly one 1.

Practice › Codeforces Solutions › Codeforces Round 948 (Div. 2) ›

CF 1977C - Nikita and LCM

We are given an array of integers. A subsequence is called special if the least common multiple of all its elements does not appear anywhere in the original array. The task is to find the maximum possible length of such a subsequence.

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CF 1977B - Binary Colouring

We are asked to represent a given positive integer $x$ as a sum of powers of two, but with a strict additional constraint: the coefficients of the powers of two can only be -1, 0, or 1, and no two non-zero coefficients can be adjacent.

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CF 1977A - Little Nikita

Nikita has a tower that starts empty, and he can perform exactly one of two operations per move: either place one cube on top or remove one cube from the top. The problem asks whether, after performing exactly n moves, the tower can have exactly m cubes.