Codeforces Round 858 (Div. 2)

Solutions for Codeforces Round 858 (Div. 2) (contest 1806). 3/7 problems verified against sample I/O. Difficulty range: 800-2900.

7 items

Codeforces Round 858 (Div. 2)

Type: Div. 2 | Problems: 7 | Verified: 3/7 | Rating range: 800-2900 | Time: 16m 33s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Walking Master	800	geometry, greedy, math	1m 51s	✓
B	Mex Master	900	constructive-algorithms, greedy	4m 50s	✗
C	Sequence Master	1600	brute-force, constructive-algorithms, math	2m 5s	✓
D	DSU Master	2500	combinatorics, dp, dsu	2m	✗
E	Tree Master	2200	brute-force, data-structures, dfs-and-similar	1m 32s	✓
F1	GCD Master (easy version)	2900	greedy, math, number-theory	2m 39s	✗
F2	GCD Master (hard version)	2900	greedy, math, sortings	1m 36s	✗

Practice › Codeforces Solutions › Codeforces Round 858 (Div. 2) ›

CF 1806F1 - GCD Master (easy version)

Working

Practice › Codeforces Solutions › Codeforces Round 858 (Div. 2) ›

CF 1806F2 - GCD Master (hard version)

We are given an array of integers where each element is at most $m$, and we are allowed to perform exactly $k$ operations. In each operation, we select two elements, remove them, and append their greatest common divisor (gcd) to the array.

Practice › Codeforces Solutions › Codeforces Round 858 (Div. 2) ›

CF 1806D - DSU Master

We are given a binary array that encodes how edges are directed between values, and we are asked to evaluate a rather indirect quantity over all permutations of each prefix length. For a fixed length $k$, we take every permutation of ${1,2,dots,k}$.

Practice › Codeforces Solutions › Codeforces Round 858 (Div. 2) ›

CF 1806E - Tree Master

The tree is rooted at vertex 1. Every vertex has a value a[v], and every vertex except the root has a parent. For a query (x, y), both vertices are guaranteed to lie at the same depth. Starting from these two vertices, we repeatedly move both upward one edge at a time.

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CF 1806C - Sequence Master

We are given an array p of length 2n. We want to modify its values and obtain another array q of the same length. The target array is not arbitrary.

Practice › Codeforces Solutions › Codeforces Round 858 (Div. 2) ›

CF 1806A - Walking Master

We are asked to compute the minimum number of moves for a character, YunQian, to reach a target point on an infinite Cartesian plane.