This is the fifth round of the 2020 series of Codeforces Global Rounds. The rounds are open and rated for everybody.
The prizes for this round are as follows:
- 30 best participants get a t-shirt.
- 20 t-shirts are randomly distributed among those with ranks between 31 and 500, inclusive.
The prizes for the 6-round series in 2020:
- In each round top-100 participants get points according to the table.
- The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
- The best 20 participants over all series get sweatshirts and place certificates.
Thanks to XTX, which in 2020 supported the global rounds initiative!
Problems for this round are set by me. Thanks a lot to the coordinator antontrygubO_o, to the testers dacin21, Giada, H4CKOM, DimmyT, postscript, oolimry, RedDreamer, PM11, Tlatoani, growup974, nvmdava, bhaskarjoshi2001, dorijanlendvaj, and to MikeMirzayanov for the Codeforces and Polygon platforms.
The round will have 8 problems and will last 180 minutes.
The (unusual) scoring distribution is: 500-750-1000-1000-1500-2250-2250-4500.
In codeforces rounds there is a minimum possible score and a maximum one. Moreover, to spice up the strategies for top contestants, I wanted to have F+G=H. Satisfying these constraints is nontrivial and has generated this scoring distribution.
The low scores for problems B-C-D-E-F-G should not suggest that they are easier than usual.
I hope you will have fun solving the problems!
UPD: The round is postponed by 15 minutes because just before the round there will be a 10-minutes-long unrated testing round. Considering the recent Codeforces downtime, this is a measure to make sure that there will not be technical issues during the real round.
UPD2: There were no technical issues during the testing round, hence the real round will happen. Good luck and see you in the scoreboard!
UPD3: I hope you liked the problems, here is the editorial.
UPD4: Congratulations to the winners!
UPD5: And congratulation to Petr who upsolved H before the editorial was posted! You made me happy!