Salam, Codeforces!

After many years, we are excited and pleased to announce that Codeforces Global Round 31 (Div. 1 + Div. 2) will be held on Dec/19/2025 17:35 (Moscow time). Thanks to XTX Markets for supporting the initiative! In 2025, we held 3 such rounds, and the series results will take into account the best 2 participations out of 3.

Codeforces Global Round 31 marks the third round in the 2025 series of Codeforces Global Rounds. These rounds are open and rated for everyone.

The prizes for this round are as follows:

• The top 30 participants will receive a t-shirt.
• 20 t-shirts will be randomly distributed among participants ranked between 31 and 500, inclusive.

The prizes for the 3-round series in 2025:

• In each round, the top-100 participants get points according to the table.
• A participant's final score will be the sum of the points they earned in their 2 highest-placing rounds.
• The top 20 participants across the series will receive sweatshirts and placement certificates.

We extend our gratitude to XTX Markets for supporting the global rounds initiative in 2025!

The problems for this round were prepared by MohammadParsaElahimanesh, Shayan, and me.

We would like to express our sincere thanks to:

• Akulyat for coordinating the round and providing valuable feedback throughout the process;
• the testers: N_z__, A_G, YuukiS, amirhoseinfar1385, ArshiaDadras, Millad, EyadBT, aimoon, michao, JeffreyLC, s.seraj.shafie, AminAnv1, abramazani, MRasool, Radman_, Hooded_Hood, tilnoene, PMiguelez, chromate00, M.H.N, CLown1331, and dina_saba for their time and effort in testing the problems;
• MikeMirzayanov and KAN for creating and maintaining the great platforms Codeforces and Polygon.

The round will feature 8 + 2 problems, and you will have 2.5 hours to solve them.

Score Distribution: $$$500 - 750 - 1500 - 1750 - 2000 - (2500 - 750) - 2750 - (3000 + 3000)$$$

Good Luck & Have Fun!

Editorial is out.

Congratulations to the winners!

1. ecnerwala

2. Kevin114514

3. kotatsugame

4. maroonrk

5. hos.lyric

6. tourist

7. JDScript0117

8. VivaciousAubergine

9. crazy_sea

10. qiuzx

Hello Codeforces!

On Oct/15/2022 17:35 (Moscow time) we will host Codeforces Global Round 23.

It is the fifth round of a 2022 series of Codeforces Global Rounds. The rounds are open and rated for everybody.

The prizes for this round:

• 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 2022:

• 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 2022 supported the global rounds initiative!

The problems were written and prepared by AmirrzwM, MohammadParsaElahimanesh and napstablook, AquaMoon, Cirno_9baka, mejiamejia, ChthollyNotaSeniorious, SSerxhs, TomiokapEace, SomethingNew, pakhomovee, rembocoder, SirShokoladina.

We would also like to thank:

• 74TrAkToR, for coordinating and helping a lot to make this round happen (and rejecting all of my problems).
• er888kh and Mp007mp for giving ideas for some problems.
• Our testers for testing and providing helpful feedbacks: er888kh, sinamhdv, SoheilE, DeadlyCritic, egfhdbfweryg123, gamegame, Kostroma, Endagorion, AndreySergunin, MELNIKOFF_OLEG, zemen, iwalainz, halin.george, -skyline-, mejiamejia, triple__a, TomiokapEace, SomethingNew, efimovpaul, Rhodoks, meowcneil, plagues, Milesian, 055D, SSerxhs, apeiya, E404_Not_Found, RUSH_D_CAT, willy108, _Veritas, oolimry, aaaaawa and Ynoi.
• MikeMirzayanov for creating great platforms Codeforces and Polygon.

Round Information:

• Duration: 2 hours and 15 minutes
• Number of problems: 7 problems and 1 sub task
• Score distribution: 500-1000-1000-1500-(2000+1750)-2500-3500
• There is an interactive problem, so please see the guide of interactive problems if you are not familiar with it.

We have tried our best to write clear problem statements and make strong pretests and we are looking forward to your participation!

UPD: Editorial