Codeforces Round 877 (Div. 2)

Solutions for Codeforces Round 877 (Div. 2) (contest 1838). 1/6 problems verified against sample I/O. Difficulty range: 800-3000.

6 items

Codeforces Round 877 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 1/6 | Rating range: 800-3000 | Time: 11m 53s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Blackboard List	800	constructive-algorithms, math	2m 2s	✗
B	Minimize Permutation Subarrays	1100	constructive-algorithms, math	1m 33s	✗
C	No Prime Differences	1400	constructive-algorithms, math, number-theory	1m 43s	✗
D	Bracket Walk	2100	data-structures, greedy, strings	2m 2s	✓
E	Count Supersequences	2500	combinatorics, dp, math	1m 27s	✗
F	Stuck Conveyor	3000	binary-search, constructive-algorithms, interactive	3m 6s	✗

Practice › Codeforces Solutions › Codeforces Round 877 (Div. 2) ›

CF 1838F - Stuck Conveyor

The earlier solution implicitly assumed: We only need to satisfy density constraints in contiguous blocks of size $k$.

Practice › Codeforces Solutions › Codeforces Round 877 (Div. 2) ›

CF 1838D - Bracket Walk

We have a bracket string. A walk starts at position 1 and must eventually end at position n. At every moment we record the bracket written at the current position.

Practice › Codeforces Solutions › Codeforces Round 877 (Div. 2) ›

CF 1838E - Count Supersequences

We are asked to count how many arrays of length $m$ over the values $1$ through $k$ contain a given array $a$ of length $n$ as a subsequence. A subsequence allows elements of $a$ to appear in order, but they do not need to be contiguous.

Practice › Codeforces Solutions › Codeforces Round 877 (Div. 2) ›

CF 1838A - Blackboard List

We are given a final list of integers that were produced by starting with two unknown numbers on a blackboard and repeatedly writing the absolute difference of any two numbers already present.

Practice › Codeforces Solutions › Codeforces Round 877 (Div. 2) ›

CF 1838C - No Prime Differences

We are asked to construct a permutation of a grid, where every integer from 1 to $n cdot m$ is placed exactly once in an $n times m$ table.

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CF 1838B - Minimize Permutation Subarrays

We are given a permutation p of length n, meaning an array containing each integer from 1 to n exactly once in some order.