Hello, Codeforces!

We are happy to invite you to participate in FAOI Round 13, officially named Fun Algorithm OI Round 13. This is the 13th public contest brought to you by the FAOI problem-setting team.
We hope you will enjoy the contest!
This round is also held in collaboration with the rhythm game Phira. We sincerely thank Phira for providing us with this opportunity! All contestants with a positive score will receive an in-game badge.
Contest Information
- Contest link: https://www.luogu.com.cn/contest/332970
- Start time: July 17, 2026, 14:00 (Beijing Time, UTC+8)
- Format: IOI-style
- Duration: 4 hours
- Number of problems: 4
- Rated: Yes, for Luogu ratings
- Difficulty: from Luogu Popularization level to Provincial Selection level
- Approximate Codeforces rating: 800–2400
Staff
We would really like to thank the following people for making this round possible:
- Coordinator: zpy12345
- Authors: Gold14526, zpy12345, Shadow_T, mahaorui2012
- Testers: Encounter_k, fanchuanyu, irris
- Reviewer: Milkcat2009
Problems
The editorials will be published after the contest.
| Problem | Title | Authors | Tester | Editorial |
|---|---|---|---|---|
| A | Push Tower | zpy12345 | Encounter_k | here |
| B | XOR and Less | Shadow_T | Encounter_k | here |
| C | addimnorsux II | mahaorui2012 | Encounter_k | here |
| D | Hi, story | Gold14526 | fanchuanyu, irris | here |
All problems have O2 optimization enabled. The time and memory limits are set to be at least 1.5 times those required by the official solutions.
We hope to see you there. Good luck and have fun!
If you are not familiar with Luogu or Chinese OI-style contests, the following posts may be helpful:



