Bok!

I am delighted to invite you to a mirror of the Croatian Olympiad in Informatics!

As part of the COCI series, we are hosting an Internet online contest with problems from the Croatian Olympiad in Informatics 2026. The contest is primarily intended for high school contestants, but it's open to all interested!

This contest is used in Croatia to select members of the IOI 2026 team. There will be three to five problems and the contest will be five hours long. The contestants will have full feedback with at most 50 submissions per task.

The problems were set by an undisclosed subset of dorijanlendvaj, keko37,ToniB and myself.

Instead of the usual mirror format, we are adopting the format where you will be given 29 hours and you can start your own 5 hours whenever you like. Notice that if you start less than five hours before the end of the contest, your window will be shorter than 5 hours.

Be careful, the timer starts once you click Register.

It will be held on Sunday, May 10, starting at 17:00 (GMT/UTC).

Check out your local times at https://hsin.hr/coci/next_contest.html.

You may use Python, Pascal, C, C++, or Java as your programming language of choice.

The two relevant websites are:

https://hsin.hr/coci/ — information about the contest

https://evaluator.hsin.hr/ — judging system

We hope that you will join us or encourage your students to do so!