Codeforces Round 925 (Div. 3)

Solutions for Codeforces Round 925 (Div. 3) (contest 1931). 4/7 problems verified against sample I/O. Difficulty range: 800-2000.

7 items

Codeforces Round 925 (Div. 3)

Type: Div. 3 | Problems: 7 | Verified: 4/7 | Rating range: 800-2000 | Time: 15m 14s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Recovering a Small String	800	brute-force, strings	1m 16s	✓
B	Make Equal	800	greedy	1m 14s	✓
C	Make Equal Again	1000	brute-force, greedy, math	1m 43s	✓
D	Divisible Pairs	1300	combinatorics, math, number-theory	3m 30s	✓
E	Anna and the Valentine's Day Gift	1400	games, greedy, math	2m 10s	✗
F	Chat Screenshots	1700	combinatorics, dfs-and-similar, graphs	2m 41s	✗
G	One-Dimensional Puzzle	2000	combinatorics, math, number-theory	2m 40s	✗

Practice › Codeforces Solutions › Codeforces Round 925 (Div. 3) ›

CF 1931G - One-Dimensional Puzzle

We are asked to count the number of ways to assemble a one-dimensional puzzle using four distinct types of tiles. Each tile has connections on the left and right, which can be a protrusion or a recess.

Practice › Codeforces Solutions › Codeforces Round 925 (Div. 3) ›

CF 1931D - Divisible Pairs

We are given an array of integers and two numbers, $x$ and $y$. A pair of indices $(i, j)$ with $i < j$ is considered "beautiful" if the sum of the two elements $ai + aj$ is divisible by $x$ and the difference $ai - aj$ is divisible by $y$.

Practice › Codeforces Solutions › Codeforces Round 925 (Div. 3) ›

CF 1931F - Chat Screenshots

We are given a chat with n participants, each identified by a unique number from 1 to n. The chat displays participants in a list ordered by activity, but each participant always sees themselves at the top of their own list.

Practice › Codeforces Solutions › Codeforces Round 925 (Div. 3) ›

CF 1931E - Anna and the Valentine's Day Gift

The game begins with a list of integers. Anna moves first by reversing the digits of any number, which can increase or decrease its value depending on the digits. Sasha moves second by concatenating any two numbers, reducing the list size by one.

Practice › Codeforces Solutions › Codeforces Round 925 (Div. 3) ›

CF 1931C - Make Equal Again

We are given an array of integers and we want to make all elements equal. We are allowed to perform at most one operation, which consists of picking a contiguous subarray and setting all its elements to some value.

Practice › Codeforces Solutions › Codeforces Round 925 (Div. 3) ›

CF 1931A - Recovering a Small String

We are given a single integer that represents the sum of three hidden lowercase letters. Each letter contributes its position in the alphabet, so a contributes 1, b contributes 2, and so on up to z contributing 26.

Practice › Codeforces Solutions › Codeforces Round 925 (Div. 3) ›

CF 1931B - Make Equal

We are given several independent scenarios. In each scenario there is a line of containers, each holding some amount of water. We are allowed to move water, but only from a container on the left to a container on the right.