Codeforces Round 921 (Div. 2)

Solutions for Codeforces Round 921 (Div. 2) (contest 1925). 4/6 problems verified against sample I/O. Difficulty range: 800-2400.

6 items

Codeforces Round 921 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 4/6 | Rating range: 800-2400 | Time: 12m 2s

Problem	Name	Rating	Tags	Solve Time	Verified
A	We Got Everything Covered!	800	constructive-algorithms, greedy, strings	1m 48s	✗
B	A Balanced Problemset?	1200	brute-force, greedy, math	1m 21s	✓
C	Did We Get Everything Covered?	1500	constructive-algorithms, dp, greedy	2m 11s	✗
D	Good Trip	1900	combinatorics, dp, math	2m 9s	✓
E	Space Harbour	2100	data-structures, implementation, math	1m 44s	✓
F	Fractal Origami	2400	geometry, math	2m 49s	✓

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 2) ›

CF 1925F - Fractal Origami

We repeatedly perform the same fold on a square sheet. Each operation folds all four corners to the center, producing a smaller square rotated by $45^circ$. After doing this $N$ times and unfolding the paper, every crease is either a mountain fold or a valley fold.

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 2) ›

CF 1925C - Did We Get Everything Covered?

This is a Type B (prove/disprove) problem. The task is to determine whether a stated property is always true: Given a closed ski track that passes through each village exactly twice, is it always possible to traverse along the track so as to visit each village exactly once?

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 2) ›

CF 1925A - We Got Everything Covered!

We are asked to build a single string over the first k lowercase letters such that every possible string of length n formed from those k letters appears somewhere inside it as a subsequence.

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CF 1925E - Space Harbour

We have a line with n positions, each containing a ship. Certain positions have harbours, each with an associated value. Every ship must eventually "move" to the next harbour to its right.

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 2) ›

CF 1925D - Good Trip

We have a graph on n children. Only m pairs are marked as friends, and each friendship edge has an initial weight f. The teacher performs exactly k excursions. During each excursion, one unordered pair of children is selected uniformly at random from all possible pairs.

Practice › Codeforces Solutions › Codeforces Round 921 (Div. 2) ›

CF 1925B - A Balanced Problemset?

We are asked to split an integer $x$ into exactly $n$ positive integers whose sum is $x$, in a way that maximizes the greatest common divisor of these integers. The input gives multiple test cases, each with values for $x$ and $n$.