Hello, April Fools lovers Codeforces!

We, AlperenT, flamestorm, ToxicPie9, and willy108, would like to invite everyone on Codeforces to April Fools Day Contest 2024! The 12th April Fools Day Contest will take place on Apr/01/2024 17:35 (Moscow time). This is a joke competition in which solving the problem is often easier than figuring out what the actual task is.

In this round, you will be given $$$n$$$ cool bugaboos where $$$-1 \le n \le \textbf{[REDACTED]}$$$ and 2 hours to solve them. The contest will use extended ICPC rules (no hacks, the standings are decided by the number of solved problems and penalty time earned on them). You can submit solutions in any language allowed by Codeforces, unless the problem says otherwise.

Please note that the round is unrated and that the penalty for a wrong submission is 10 minutes.

To get an idea of what the contest will look like, you can check out the contests of the past years: 2012, 2013, 2014, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023. (It has been 12 years since the first April Fools Day Contest, thank you Nickolas!)

Please do not send any clarification requests in the contest, as we definitely will not be sending funny responses like we did last year.

Good luck, and have fun!

UPD: Editorial is released!

UPD: Congrats to the winners:

1. tiger2005
2. emthrm
3. Enchom
4. arvindf232
5. KumaTachiRen

And the first solves on each problem:

• A: InternetPerson10
• B: Mr_Buffon
• C: Thienu
• D: moraprex
• E: BalintR
• F: SanguineChameleon
• G: 7_divided_by_3
• H: Owmicron
• I: Dog_of_zzx
• J: Joshc

Hello Codeforces!

As last year, we are happy to invite IOI 2023 participants and leaders to the International Olympiad in Informatics Discord server. We currently have around 75 members from 2023, 190 from 2022, 100 from past IOIs, and 25 team leaders.

This server is a great way to get to know new people who are also participating in the Olympiad, make plans with them, share advice, and even practice together! The server also has multiple useful bots including TLE and Contest Reminder.

If you are or were an IOI delegation member, please feel free to become a part of the community using the following link.

Thank you for participating in our contest! We hope you enjoyed it.

Please let us know what you thought of the problems by voting!

1812A - Are You a Robot?

Idea: ToxicPie9
Preparation: flamestorm

1812B - Was it Rated?

Idea: BucketPotato
Preparation: BucketPotato

1812C - Digits

Idea: ToxicPie9
Preparation: ToxicPie9

1812D - Trivial Conjecture

Idea: AlperenT
Preparation: AlperenT

1812E - Not a Geometry Problem

Idea: ToxicPie9
Preparation: ToxicPie9

1812F - Factorization

Idea: flamestorm
Preparation: flamestorm

1812G - Colour Vision

Idea: flamestorm
Preparation: flamestorm

1812H - Expected Twist

Idea: ToxicPie9
Preparation: ToxicPie9

1812I - Mountain Climber

Idea: Ari
Preparation: Ari

1812J - Unmysterious Language

Idea: ScarletS, ToxicPie9, et al.
Preparation: ToxicPie9, ChatGPT

I fell to candidate master after the contest TypeDB Forces 2023 (Div. 1 + Div. 2, Rated, Prizes!). However, just before the contest Codeforces Round 848 (Div. 2), there was a rating rollback, and I became master again. Because of this, I had to register for Div. 2 as out of competition. I was expecting this to be calculated but seems like it didn't because others had a rating change while I didn't. If it's possible, can this be fixed please?

Hello Codeforces!

SlavicG and I have put together the "International Olympiad In Informatics" discord server! The server is aimed to be a place where the IOI community can chat, relax, make plans, share pictures, give and receive advice, help each other and of course, have fun! IOI participants and any other delegation members from any year are welcome on the server!

If you fit in any of the categories feel free to join the server using the following link.