Hi all,

The Central European Olympiad in Informatics (CEOI) 2022 is starting on Sunday and we'd like to invite you to participate in two online mirror contests that will feature the same problems as the two competition days.

The day 1 mirror will take place on Tuesday, July 26th, 10:00 CEST, and day 2 mirror will take place on Thursday, July 28th, 10:00 CEST. Both contests will last for 5 hours, contain 3 IOI-style problems, and have full-feedback.

In order to participate in the CEOI 2022 Online Mirror contests, you'll need an account on evaluator.hsin.hr. After logging in, you can register for the Mirror contests on the "Events" page.

Hope you'll enjoy the contests.

Hi all,

The Central European Olympiad in Informatics (CEOI) 2021 is starting tomorrow and we'd like to invite you to participate in two online mirror contests that will feature the same problems as the two competition days.

The day 1 mirror will take place on Thursday, September 2nd, 11:00 CEST, and day 2 mirror will take place on Saturday, September 4th, 11:00 CEST. Both contests will last for 5 hours, contain 3 IOI-style problems, and have full-feedback.

In order to participate in the CEOI 2021 Online Mirror contest, you'll need an account on evaluator.hsin.hr. After logging in, you can register for the Mirror contests on the "Events" page.

Hope you'll enjoy the contests.

Hi all,

the final stage (following COI) of Croatian IOI team selection consists of two final exams. The points from two exams are added to COI scores and the best four students are selected into the IOI team.

These two exams are IOI-style competitions, featuring three problems and lasting for five hours. This year, we have decided to bring back the open mirror competition.

Therefore, we invite you to join us on Saturday for the first exam, and Sunday for the second exan.

You can register for the contests here.

Hope you'll enjoy the contests.

Hi all,

Croatian Olympiad in Informatics (COI) represents the first major step towards forming the Croatian IOI team. As you know, we usually hold an online mirror of this contest as the last round of the COCI season.

On that note, I'm happy to invite you to join us on Sunday, April 25, starting at 14:00 (GMT/UTC). The contest will feature 3 to 5 IOI-style tasks and it will last for 5 hours. You will also have full feedback with at most 50 submissions per task.

You can access the judging system here. The registration period ends 1 hour before the beginning of the contest (look it up under "Events").

Hope you'll enjoy the contest.

Hi all,

Croatian Olympiad in Informatics (COI) represents the first major step towards forming the Croatian IOI team. As you know, we usually hold an online mirror of this contest as the last round of the COCI season. Since this year is already unusual, we decided it was ok to postpone the online version of the contest until we have a (hopefully) stable version of the new judging system.

On that note, I'm happy to invite you to join us on Saturday, October 3, starting at 15:00 (GMT/UTC). The contest will feature 4 IOI-style tasks and it will last for 5 hours. You will also have full feedback with at most 50 submissions per task.

You can access the judging system here. The registration period ends 1 hour before the beginning of the contest (look it up under "Events"). If you wish to get a bit more familiar with the system, we have uploaded the last 14 COCI seasons for you to practice on. Most problems (except for the very easy ones) have English translations. Also, some custom checkers have been lost during the years so some problems might be wrongly judged, we will fix that along the way. In general, the more recent the season, the greater chance for the checkers to be correct. This judge will be used for the next COCI season.

The tasks were prepared by: tonkosi, abeker, paula, dpaleka, Shtef, ipaljak and mkisic.

Hope you'll enjoy the contest.

Hi all,

join us on the sixth round which will be held on Saturday, March 7th at 14:00 UTC.

If you are not familiar with the COCI contest format, we encourage you to read the announcement for the new season. You can also find the problems from the previous rounds here.

Feel free to discuss the problems in the comment section after the contest ends.

See you on Saturday!

Hi all,

join us on the fifth round which will be held on Saturday, February 8th at 14:00 UTC.

If you are not familiar with the COCI contest format, we encourage you to read the announcement for the new season. You can also find the problems from the previous rounds here.

Feel free to discuss the problems in the comment section after the contest ends.

See you on Saturday!

Hi all,

join us on the fourth round which will be held on Saturday, January 18th at 14:00 UTC.

If you are not familiar with the COCI contest format, we encourage you to read the announcement for the new season. You can also find the problems from the previous rounds here.

Feel free to discuss the problems in the comment section after the contest ends.

See you on Saturday!

Hi all,

join us on the third round which will be held on Saturday, December 14th at 14:00 UTC.

If you are not familiar with the COCI contest format, we encourage you to read the announcement for the new season. You can also find the problems from the previous rounds here.

Feel free to discuss the problems in the comment section after the contest ends.

See you on Saturday!

Hi all,

join us on the second round which will be held on Saturday, November 16th at 14:00 UTC.

If you are not familiar with the COCI contest format, we encourage you to read the announcement for the new season. You can also find the problems from the first round here.

Feel free to discuss the problems in the comment section after the contest ends.

See you on Saturday!

Hi all,

it's the most wonderful time of the year as the new season of COCI is getting near :)

Join us on the first round which will be held on Saturday, October 19th at 14:00 UTC.

If you are not familiar with COCI contest format, we encourage you to read the announcement for the new season. Also, this year we have decided to allocate the same number of points to the three hardest tasks and present them in lexicographical order in the problemset.

Feel free to discuss the problems here after the contest ends.

See you on Saturday!

Hi all,

Croatian Olympiad in Informatics (COI) represents the first major step towards forming the Croatian IOI team. This year's edition will take place on Sunday, April 14th at 15:00 UTC. As usual, we will host an online mirror of the contest for which you can register here.

The contest format is similar to IOI — it lasts for 5 hours and will contain 3 to 5 problems. The test cases for each problem are divided into subtasks of varying difficulties so it is possible to receive partial score. The contestants will be able to receive full feedback on a limited number of submissions per task.

The contest is organized by Mr. Malnar and the problemset was prepared by satja, DBradac, mislav_bradac, tonkosi and myself. We hope you'll enjoy the contest.

See you on Sunday!