Codeforces Round 897 (Div. 2)

Solutions for Codeforces Round 897 (Div. 2) (contest 1867). 1/7 problems verified against sample I/O. Difficulty range: 800-2700.

7 items

Codeforces Round 897 (Div. 2)

Type: Div. 2 | Problems: 7 | Verified: 1/7 | Rating range: 800-2700 | Time: 13m 50s

Problem	Name	Rating	Tags	Solve Time	Verified
A	green_gold_dog, array and permutation	800	constructive-algorithms, sortings	1m 34s	✗
B	XOR Palindromes	1100	bitmasks, constructive-algorithms, strings	4m 6s	✗
C	Salyg1n and the MEX Game	1300	constructive-algorithms, data-structures, games	1m 43s	✗
D	Cyclic Operations	1800	brute-force, constructive-algorithms, dfs-and-similar	2m 6s	✗
E1	Salyg1n and Array (simple version)	2000	constructive-algorithms, interactive, math	1m 35s	✗
E2	Salyg1n and Array (hard version)	2200	constructive-algorithms, interactive	1m 39s	✗
F	Most Different Tree	2700	brute-force, constructive-algorithms, dfs-and-similar	1m 7s	✓

Practice › Codeforces Solutions › Codeforces Round 897 (Div. 2) ›

CF 1867E2 - Salyg1n and Array (hard version)

We are given an array of hidden integers and a fixed segment length $k$. We are not allowed to directly inspect the array, but we can ask queries on any contiguous block of exactly $k$ elements.

Practice › Codeforces Solutions › Codeforces Round 897 (Div. 2) ›

CF 1867F - Most Different Tree

We start with a rooted tree $G$ on $n$ vertices, rooted at vertex $1$. For every vertex $v$, we look at the “subtree of $v$” defined as all vertices whose path from the root passes through $v$.

Practice › Codeforces Solutions › Codeforces Round 897 (Div. 2) ›

CF 1867B - XOR Palindromes

We are given a binary string and we are allowed to “modify” it using another binary string of the same length. That second string is not arbitrary in its effect, because it is constrained only by how many ones it contains.

Practice › Codeforces Solutions › Codeforces Round 897 (Div. 2) ›

CF 1867D - Cyclic Operations

We start with an array a of length n filled with zeros, and we want to transform it into a target array b of the same length.

Practice › Codeforces Solutions › Codeforces Round 897 (Div. 2) ›

CF 1867E1 - Salyg1n and Array (simple version)

We are given a hidden array of length $n$, where each element is an integer. We do not see the array directly. Instead, we are allowed to ask queries on contiguous segments of fixed length $k$.

Practice › Codeforces Solutions › Codeforces Round 897 (Div. 2) ›

CF 1867C - Salyg1n and the MEX Game

We are given a sorted set of distinct integers. We do not control this set directly; instead, we interact with an opponent through moves that change it. Each move we either insert a new number into the set or allow Bob to remove a number under a restriction.

Practice › Codeforces Solutions › Codeforces Round 897 (Div. 2) ›

CF 1867A - green_gold_dog, array and permutation

We are given an array a of length n. We must construct a permutation b of numbers from 1 to n such that when we subtract element by element, forming ci = ai - bi, the number of distinct values appearing in c is as large as possible.