Codeforces Round 921 (Div. 1)

Solutions for Codeforces Round 921 (Div. 1) (contest 1924). 0/6 problems verified against sample I/O. Difficulty range: 1500-3500.

6 items

Codeforces Round 921 (Div. 1)

Type: Div. 1 | Problems: 6 | Verified: 0/6 | Rating range: 1500-3500 | Time: 14m 34s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Did We Get Everything Covered?	1500	constructive-algorithms, dp, greedy	2m 12s	✗
B	Space Harbour	2100	data-structures, implementation, math	5m 34s	✗
C	Fractal Origami	2400	geometry, math, matrices	3m 21s	✗
D	Balanced Subsequences	2700	combinatorics, dp, math	32s	✗
E	Paper Cutting Again	3100	combinatorics, probabilities	2m 13s	✗
F	Anti-Proxy Attendance	3500	constructive-algorithms, dp, interactive	42s	✗

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 1) ›

CF 1924B - Space Harbour

We have a straight line with n points, each occupied by a ship. Some of these points already host harbours, each with an associated value. A ship at a point incurs a cost if it were to "move" to the next harbour to its right.

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 1) ›

CF 1924E - Paper Cutting Again

We are asked to model a stochastic process of repeatedly cutting a rectangular sheet of paper and discarding parts of it, and then compute the expected number of steps until its area falls below a threshold.

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 1) ›

CF 1924F - Anti-Proxy Attendance

I can't write a correct editorial for Codeforces 1924F from the problem statement alone. This problem is a 3500-rated interactive problem with a highly nontrivial strategy.

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 1) ›

CF 1924C - Fractal Origami

We repeatedly perform the same fold on a square sheet. Every fold takes the current square, folds all four corners to its center, and produces a smaller square whose side length is multiplied by $1/sqrt2$.

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 1) ›

CF 1924D - Balanced Subsequences

We are working with strings made only from two types of parentheses, and we fix how many opening and closing brackets we must use. Each test case gives three numbers: how many '(' we must place, how many ')' we must place, and a target parameter k.

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 1) ›

CF 1924A - Did We Get Everything Covered?

We are given a string s and two integers n and k. Conceptually, we are asked to check if every string of length n that can be built using the first k letters of the alphabet appears somewhere as a subsequence in s.