Codeforces Round 821 (Div. 2)

6 problems from Codeforces Round 821 (Div. 2) (contest 1733), difficulty 800-2700. 1/6 solutions verified against sample I/O.

6 items

Codeforces Round 821 (Div. 2)

Div. 2 | 6 problems | 1/6 verified | Difficulty 800-2700 | 22m 13s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Consecutive Sum	800	greedy, sortings	21,855	4m 30s	✓
B	Rule of League	900	constructive-algorithms, math	21,072	3m 27s
C	Parity Shuffle Sorting	1300	constructive-algorithms, sortings	17,095	3m 23s
D1	Zero-One (Easy Version)	1400	constructive-algorithms, greedy, math	15,030	3m 38s
D2	Zero-One (Hard Version)	2000	dp, greedy	4,738	2m 51s
E	Conveyor	2700	constructive-algorithms, dp, math	1,486	4m 24s

Practice › Codeforces Solutions › Codeforces Round 821 (Div. 2) ›

CF 1733E - Conveyor

The system describes a 120 by 120 grid where every cell initially contains a conveyor belt pointing to the right. A single slime starts at the top-left cell, and every second the system evolves in a synchronized way.

Practice › Codeforces Solutions › Codeforces Round 821 (Div. 2) ›

CF 1733D1 - Zero-One (Easy Version)

We are given two binary strings of equal length. We are allowed to repeatedly apply an operation that flips two positions at once: pick indices l and r with l < r, and invert both bits. The cost depends only on whether the chosen positions are adjacent or not.

Practice › Codeforces Solutions › Codeforces Round 821 (Div. 2) ›

CF 1733D2 - Zero-One (Hard Version)

We are given two binary strings of equal length. We are allowed to fix mismatches between them by flipping pairs of positions in the first string. Each operation picks two different indices and toggles both bits at those positions.

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CF 1733A - Consecutive Sum

We are given an array of integers, and we are allowed to rearrange elements using a restricted swap operation. The restriction is that we can only swap positions whose indices share the same remainder when divided by a fixed number $k$.

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CF 1733B - Rule of League

We are given a very specific elimination-style tournament. Players arrive in a fixed order from 1 to n. The first match is between player 1 and player 2, then the winner of that match plays player 3, then that winner plays player 4, and so on until player n.

Practice › Codeforces Solutions › Codeforces Round 821 (Div. 2) ›

CF 1733C - Parity Shuffle Sorting

We are given an array of integers and a peculiar operation that allows us to “transfer” values between two positions, but the direction of the transfer depends entirely on the parity relationship between the chosen pair. Each operation picks two indices l < r.