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 2025. 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 2025 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, Agnus, 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, April 27, 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!
Excited to participate, just wanted to mention that https://hsin.hr/coci/next_contest.htm still gives Feburary 15th as the next contest date.
Hope nvujica gets top 4. He taught me a lot about cp and he is my favorite programmer. Unfortunately, I was not called to participate, but hopefully I can also get in the team next year.
he did indeed get into top 4, top 1 actually.
Great news for nvujica! Also for almost all my favorites, including lukadu and masa.dobric who took the top 9 which means they go to the second round and can get close to that 4th place because the difference in points is very small (actually, it's average). The trophy is ours!
Friendly reminder! The window opens in 6 hours.
is there a way to un-register? i want to take contest tomorrow, but i have already registered.
I also have the same problem
Edit: Ok, it looks like everything is fine
I have the same issue. I accidently clicked on register, thinking it was something I'd have to do to eventually give the contest, but my window started.
When will Izborne Pripreme be
Next week
Constructive Olympiad in Informatics.
Is there editorial?
Is there editorial of HIO last year?
https://errorgorn.github.io/2024/04/30/COI.html
It's not official, but it's editorial
How to solve task Bolivija?
You can imagine the interval between a[i] and a[n — i] as being a zone which you can’t make symmetrical, then make a lazy segment tree where you maintain the minimum and the number of possible valid pairs L,R within the range of your node
Can we get the in-person scoreboard of COI?
Here you go! https://hsin.hr/hio2025/rezultati.php
where tasks can be upsolved?
How to solve C and D?
Where is it possible to upsolve the problems and make submissions after the contest have ended?
Why are contests not added to the HSIN Evaluator for upsolving, like COI 2024 and COI 2025? I don't know the details but if you hold the mirror, how hard can it be to just make them public for upsolving?
Hi everyone, I made ChatGPT (Its not very easy to make it generate a latex file) make a translation for the next stage of COI (Izborne Pripreme) you can view it here (the translation and layout isnt the best)
Hey, you might need to change the permissions
Im very sorry it should be working now
Where can I find the tasks? I looked at evaluator.hsin.hr, but couldn't find them sadly...