Codeforces Round 1090 (Div. 4)

7 problems from Codeforces Round 1090 (Div. 4) (contest 2218), difficulty 800-1800. 1/7 solutions verified against sample I/O.

7 items

Codeforces Round 1090 (Div. 4)

Div. 4 | 7 problems | 1/7 verified | Difficulty 800-1800 | 13m 16s

#	Problem	Rating	Tags	Accepted	Time	✓
A	The 67th Integer Problem	800	brute-force, games, implementation	34,685	1m 27s	✓
B	The 67th 6-7 Integer Problem	800	greedy, math	33,439	1m 49s
C	The 67th Permutation Problem	800	constructive-algorithms, greedy, math	26,259	2m 4s
D	The 67th OEIS Problem	1100	constructive-algorithms, greedy, math	18,287	2m 1s
E	The 67th XOR Problem	1200	binary-search, bitmasks, brute-force	13,949	1m 52s
F	The 67th Tree Problem	1500	constructive-algorithms, implementation, trees	7,202	1m 49s
G	[The 67th Iteration of ](https://codeforces.com/problemset/problem/2218/G)	1800	implementation, math	3,565	2m 14s

Practice › Codeforces Solutions › Codeforces Round 1090 (Div. 4) ›

CF 2218F - The 67th Tree Problem

We are asked to build a rooted tree on exactly $x+y$ labeled nodes, with node $1$ designated as the root. For every node $u$, we look at its subtree, meaning all nodes whose path to the root passes through $u$, including $u$ itself.

Practice › Codeforces Solutions › Codeforces Round 1090 (Div. 4) ›

CF 2218E - The 67th XOR Problem

We are given an array of non-negative integers. We perform a sequence of operations until only one element remains. Each operation consists of picking an element, XORing it with all elements of the current array, and then removing it.

Practice › Codeforces Solutions › Codeforces Round 1090 (Div. 4) ›

CF 2218C - The 67th Permutation Problem

The task is to construct a permutation of length $3n$ where we partition it into $n$ consecutive blocks of three elements each, and then take the median of each block. Our goal is to maximize the sum of these medians.

Practice › Codeforces Solutions › Codeforces Round 1090 (Div. 4) ›

CF 2218D - The 67th OEIS Problem

We are asked to construct sequences of integers of a given length such that the greatest common divisor of every consecutive pair is unique.

Practice › Codeforces Solutions › Codeforces Round 1090 (Div. 4) ›

CF 2218B - The 67th 6-7 Integer Problem

We are given exactly seven integers. The task is to negate six of them-multiply them by -1-and leave one unchanged, then compute the sum. We want the maximum sum achievable by choosing which six to negate.

Practice › Codeforces Solutions › Codeforces Round 1090 (Div. 4) ›

CF 2218A - The 67th Integer Problem

The problem asks us to pick an integer $y$ for a given integer $x$ so that the minimum of $x$ and $y$ is as large as possible. We are given multiple test cases, each consisting of a single integer $x$ between -67 and 67.