Codeforces Round 853 (Div. 2)

Solutions for Codeforces Round 853 (Div. 2) (contest 1789). 2/6 problems verified against sample I/O. Difficulty range: 800-2700.

6 items

Codeforces Round 853 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 2/6 | Rating range: 800-2700 | Time: 13m 28s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Serval and Mocha's Array	800	brute-force, math, number-theory	2m 50s	✗
B	Serval and Inversion Magic	800	brute-force, implementation, strings	1m 30s	✓
C	Serval and Toxel's Arrays	1500	combinatorics, dp, implementation	1m 43s	✗
D	Serval and Shift-Shift-Shift	2200	bitmasks, brute-force, constructive-algorithms	2m 11s	✗
E	Serval and Music Game	2500	brute-force, dp, implementation	3m 24s	✗
F	Serval and Brain Power	2700	bitmasks, brute-force, dp	1m 50s	✓

Practice › Codeforces Solutions › Codeforces Round 853 (Div. 2) ›

CF 1789E - Serval and Music Game

We are given a strictly increasing sequence of positive integers, and the largest element of this sequence plays a special role. Let us call this largest value $S$. For every integer $x$ from $1$ to $S$, we derive two numbers: the floor and ceiling of $S/x$.

Practice › Codeforces Solutions › Codeforces Round 853 (Div. 2) ›

CF 1789F - Serval and Brain Power

We are asked to find the length of the longest "powerful" subsequence of a given string. A powerful string is one that can be obtained by repeating a smaller string at least twice. Formally, if some string $T'$ can be repeated $k ge 2$ times to form $T$, then $T$ is powerful.

Practice › Codeforces Solutions › Codeforces Round 853 (Div. 2) ›

CF 1789D - Serval and Shift-Shift-Shift

We are given two binary numbers a and b of length n, and we want to transform a into b using a series of XOR-shift operations.

Practice › Codeforces Solutions › Codeforces Round 853 (Div. 2) ›

CF 1789A - Serval and Mocha's Array

We are given several test cases, each consisting of a small array of positive integers. For each array, we are allowed to reorder its elements arbitrarily. After choosing an order, we inspect every prefix of length at least two and compute the gcd of that prefix.

Practice › Codeforces Solutions › Codeforces Round 853 (Div. 2) ›

CF 1789C - Serval and Toxel's Arrays

We are given an initial array containing distinct values, and then a sequence of updates. Each update changes exactly one position, and after every update the array still contains distinct values.

Practice › Codeforces Solutions › Codeforces Round 853 (Div. 2) ›

CF 1789B - Serval and Inversion Magic

We are given a binary string consisting only of 0s and 1s. The task is to determine whether we can make it a palindrome by flipping exactly one contiguous segment of the string. Flipping a segment means changing every 0 in that segment to 1 and every 1 to 0.