The International Olympiad in Informatics 2022 is scheduled to start in a month. To help you prepare today, we announce an online judge with IOI problems. Right here, on codeforces.
Available now
On https://ioi.contest.codeforces.com/ you can find a contest for each day of each IOI contest since 2002. Participate virtually in a 5-hour contest or simply upsolve problems there! Virtual participants will appear in separate scoreboards for each year as well as in an upsolving scoreboard. Don’t forget to disable coach mode to appear in the upsolving scoreboard.
Future work
We have at least some problem materials for contests since 1998, but IOI has had competitive programming problems since 1994. Even if these problems are not very useful for training, they have significant historical value. Unfortunately, early-year materials on ioinformatics.org are incredibly bad, so if you have something (e.g., solutions, interactor, checkers, library sources), please contact me right away!
I am also considering adding original contest results as ghost participants to the scoreboards.
Let me know in the comments, what else would you like to see in the IOI archive?
How to help?
I'm sure some problems are misconfigured. The most probable errors are tests in wrong subtasks or changes in grader not mentioned in the problem statements. Let’s find them in upsolving mode, to avoid ruining the training process for contestants. If you have solutions (preferably partial solutions), please, become an early tester. Report issues via github repo. Pull requests to problem statements and validators are also always welcome there!
Please, contribute with contest materials for earlier IOI!
If you are a member of an IOI committee, help the project a lot by enforcing a better archival process for the future contests. In particular, it would be great to have as part of the public archive:
- Statements in markdown
- Any kind of non-English statements
- Test data generators and tests generation command lines
- Any description of solutions intended behavior or score
- no new archive format every year :)
Special thanks
- MikeMirzayanov and geranazavr555 for implementing a lot of stuff in Codeforces and Polygon
- ligaydima , Dimitrys and especially Masha237 for help converting problem statements to polygon format.
- lperovskaya for maintaining archive on contest.yandex.ru/ioi, which become a great material source, as well as for proofreading this text
- Petr for solutions and other materials of IOI2002 (and IOI2000, and IOI2001 I hope to publish later).
- eduardische for showing me the old IOI site with problem materials, and Martins Opmanis for maintaining it.
- yeputons for original archive resources and idea back in 2011
- Mazaalai for better than original one solutions of IOI2003-reverse
Updates
10.08.2022: IOI 2022 day 1 is available.
13.08.2022: IOI 2022 day 2 is available.
30.08.2023: IOI 2023 day 1 is available.
01.09.2023: IOI 2023 day 2 is available.
03.09.2024: IOI 2024 day 1 is available (no statements now) 05.09.2024: IOI 2024 day 2 is available (no statements now)
