This problem set will come from day 1 of the competition. The round will not be rated.

There will be 3 problems to solve in 4 hours. Partial scoring may be available on some problems. The maximum score on a single problem is 25.

## Problems

Problem Points AC Rate Users
CCO '20 P1 - A Game with Grundy 10p 18.9% 127
CCO '20 P2 - Exercise Deadlines 15p 30.7% 159
CCO '20 P3 - Mountains and Valleys 40p 4.2% 12

• commented on May 28, 2020, 1:25 a.m.

Will there be tutorials after the contest?

• commented on May 27, 2020, 9:55 p.m.

What is the solution for p3 (maybe even )? I could dig up only a solution by iterating over all pairs of bad edges and calculating answer (check every possible ordering of them in my tour) if we use only those edges for teleportation.

• commented on May 27, 2020, 10:11 p.m. edited

Hint: you only need to consider using 0 or 1 heavy edge.

• commented on May 27, 2020, 10:29 p.m.

Aaa... I see... I loosely set an upper bound on #heavy of if and if during contest.

• commented on May 27, 2020, 7:02 p.m.

Will there be editorials after the contest?

• commented on May 27, 2020, 2:02 p.m.

In order to keep the scoreboard fun for everyone, we ask that you don't participate in this contest if you participated in the official CCO today. Thanks!

• commented on May 26, 2020, 11:36 p.m.

Can the mirror be windowed?

• commented on May 27, 2020, 12:31 a.m.

It's not a rated contest so you can just solve the problems at any time after the contest too. We think the benefit of having everyone who can start at the same time discuss the solutions at the same time after the contest will outweigh the benefits of windowing the contest time.