Всем привет!

В ближайшее воскресенье, 2 февраля 2025 года в 15:00 состоится первая личная интернет-олимпиада для школьников, которая также является первым отборочным этапом на ИОИП.

Вместе с ней открывается сезон личных интернет-олимпиад, который завершится финальным этапом ИОИП. Отборочные этапы являются независимыми, лучшие участники в каждом из отборочных этапов получают проход в финал. Более подробную информацию про отборы и автопроходы можно найти на официальной странице ИОИП.

Продолжительность олимпиады — 5 часов. Не забудьте зарегистрироваться на цикл личных интернет-олимпиад в этом сезоне перед началом олимпиады. Обратите внимание, что для участия в личных олимпиадах, нужно зарегистрировать участника (по ссылке "Новый участник"). Дополнительную информацию, а также расписание всех предстоящих интернет-олимпиад можно посмотреть на страничке интернет-олимпиад.

Условия появятся на сайте в момент начала олимпиады, а также на вкладке "Файлы" в тестирующей системе. Тестирующая система находится по адресу pcms.itmo.ru.

Олимпиаду для вас подготовили Даниил Орешников (doreshnikov), Даниил Голов (DanGolov), Павел Скобелин (pskobx), Ильнур Валеев (OrleanMagic) и Иван Пальченков.

Для связи с жюри можно использовать адрес электронной почты iojury@gmail.com.

Удачи!

Update: тренировка по задачам олимпиады доступна на Codeforces: Интернет-олимпиады, Сезон 2024-2025, Первая личная олимпиада.

Hi Codeforces!

As the Chinese New Year approaches, we are glad to invite you to our Codeforces Round Ethflow Round 1 (Codeforces Round 1001, Div. 1 + Div. 2) which will be held on Jan/26/2025 17:35 (Moscow time). You will be presented with $$$8$$$ problems, one of which is divided into two subtasks, and $$$2.5$$$ hours to solve them. This round will be rated for all participants.

This round is the first Div. 1 + Div. 2 round on Codeforces with a four-digit round number, and it is also my first round. We hope you will enjoy this round.

Great thanks to:

• SSerxhs for helping me prepare most problems,
• Yakumo_Ran for providing some problems,
• TheScrasse for good coordination of this round,
• Alexdat2000 for translating all statements to Russian,
• EvenImage, ugly2333, dXqwq, Sugar_fan, propane, LuCpp, triple__a, PinkieRabbit, fallleaves01, thenymphsofdelphi, N_z__, tarjen, tiger2005, golomb, Tobo, add10k, Kieray, meowcneil, huansir, Phantasmagorias, Cai_Guang, fr200110217102, Nanani, shstyle., Theresa_Apocalypse, wjy666, PaperCloud, Kepy, _Sherbiny, nnv-nick, EternalJourney, shendeliliang, Alex2025_qwq, sabino1, larush, Kraska, yorisou, umazing, Enderwitherzjdl for testing our round,
• MikeMirzayanov for the amazing Codeforces and Polygon platforms.

Good luck & Have fun!

upd1: The score distribution is as follows: $$$500 - 1000 - 1000 - 2000 - (1500 + 2500) - 3500 - 4000 - 4500$$$

A few words from our sponsor:

Hello, Codeforces!

We are Ethflow, a proprietary trading fund specializing in cryptocurrency trading, and we’re glad to host our first Codeforces round!

Participants will have a chance to win T-shirts:

• The top 50 ranked competitors.
• 50 random participants who solve at least 3 problems and rank below 50th place.

Our team includes Codeforces grandmasters, IOI/IMO medalists, and ICPC Finals competitors. At Ethflow, we value people and create an environment where you can focus on challenges you enjoy, exploring everything from infrastructure to analytics without toxic practices. To join our team, please fill out the form.

Good luck to all participants!

upd2: Editorial

Congratulations to the winners!

1. zhoukangyang
2. ksun48
3. tourist
4. squareOf105
5. potato167

Hello, Codeforces! We are Ethflow — proprietary trading fund, specializing in cryptocurrency trading. We are glad to host our first Codeforces round!

All participants will have a chance to win T-shirts (top 50 + 50 random participants who ranked below 50th place and solved at least 3 problems).

Many of our team members, such as VEGAnn, _Time_Lord_, welleyth, FLEA, vgzowski and others, are former Codeforces participants, including our CEO, altruist and CTO, SoMuchDrama. Now, some of them were involved in four different roles over time: first as participants, then as teachers and problem setters, and now as sponsors. Currently, our team includes 7 IOI medalists, 1 IMO medalist, as well as ICPC Finals participants from both the previous and current years.

Ethflow is not just yet another HFT company. The core of our culture is putting people first, we create an environment and atmosphere where you can choose the problem you enjoy and excel at, with the freedom to explore everything from infrastructure to analytics problems. We do not tolerate toxic work culture or 60h per week mandatory working. We do believe in a decentralized finance future and work with cutting edge blockchain technology. Fortunately for the participants, we didn’t create the problems ourselves this time (maybe next time)

WARNING! If you want to work with us – please don’t. We want you to focus on real world problems, creating economic value and something useful for society, as all people know proprietary trading is not such a thing (you can ask your friends from big tech companies, they will say so). In the AI era with AGI on the horizon by 2030, there will be more awesome applications and areas where you can bring something valuable and apply your mind. There is no way back.

If nothing from above helped, please welcome — link to the form.

Hello Codeforces, and the legends of across $$$999$$$ and more rounds!

wuhudsm, Think_Only_Once, and I are beyond excited to invite you to Codeforces Round 1000 (Div. 2) at Jan/22/2025 15:05 (Moscow time). Please note the unusual time of the round ($$$\color{red}{2.5}$$$ hours before the usual time)!

The contest contains $$$6$$$ carefully crafted tasks, one of them divided into two subtasks, to be solved in $$$2$$$ hours. You will solve tasks themed around Little John and his shenanigans aimed towards getting his own dream home (featuring, probably, galvanized square steel).

This round could not exist without the thankful help of these so many people:

• FairyWinx for rejecting more tasks than are used in the final problemset, coordinating the round and translating the problems;
• rewhile for some very important "technical assistance";
• the testers of Codeforces Round 960 (Div. 2), who had tested a non-empty subset of the problemset;
• antontrygubO_o for nutella testing;
• Dominater069, _istil, Error_Yuan, Monogon, awesomeguy856 for red testing;
• defnotmee, Proof_by_QED, -firefly-, Intellegent, efishel, priyanshu.p, amoeba4, evenvalue, cry, Friedrich, temporary1 for yellow testing;
• Wxssim, HusseinFarhat, Mukundan314, turska, rewhile, redheadphone for purple testing;
• Dragokj03, VladiG, ProofByContradiction_, phir., mathtsai, beaten_by_ai, redpanda, larush, satyam343, antares2262, ismailfateen for blue testing;
• Valenz, shuniko for cyan testing;
• Dominater069 for identifying as green;
• tibinyte2006 for legendary-fake-lying-face grey testing;
• a few people who were invited to test but forgot/didn't have time for it;
• a few people who tested $$$\mathcal{O}(1)$$$ tasks individually but not the entire problemset;
• MikeMirzayanov for great platforms Codeforces and Polygon;
• and last but not least, You for participating! Thank you for writing legends in real-time for across $$$999$$$ and more rounds!

The score distribution is as follows.

Before finishing the announcement, I would like to spoil you a little of how the round's story ends.

Little John worked hard, honest and diligent for years, and finally got a home of his dream.

In that sense, I want You to be like Little John in this round.

Hard, honest and diligent will give you the rewards you deserve.

Anyways, that's all for the announcement; Good luck, and have fun!

UPD1: The score distribution has been announced.

UPD2: The editorial is posted here. Also we have good news that I will post as a separate report blog soon...

UPD3: Congratulations to the winners!

All participants:

1. sunjia (oops, the user is gone now)
2. Golovanov399
3. maspy
4. jiangbowen
5. A_G
6. fnoihzhyan

Rated only:

1. sunjia (oops, the user is gone now)
2. fnoihzhyan
3. RGB_ICPC9
4. wangzirui123
5. Network_Error
6. BSpioneer

UPD4: Anti-LLM Evaluation Report is published — the first of its kind for Div.2! Please kindly take a look if you have some free time or are just interested.

Hello, Codeforces!

We are pleased to invite you to IAEPC Preliminary Contest (Codeforces Round 999, Div. 1 + Div. 2).

The Preliminary Contest is a rated contest for Div. 1 + Div. 2, taking place on Jan/20/2025 17:35 (Moscow time). The problems for this round were prepared by EvenImage and zhoukangyang.

The top 50 contestants at least 18 years old will be invited to participate in the onsite finals. We will cover the travel expenses for onsite contestants. The finals are scheduled to take place in CUHK from February 27 to March 2, 2025.

The prizes for first place, second place, and third place of the onsite final are 10000, 5000, and 3000 USD.

More prizes and detailed information will be announced soon. You can visit International AI Elite Programming Contest for information.

We would like to thank:

• MikeMirzayanov for the Codeforces and Polygon platforms.
• Sugar_fan for coordinating the round.
• Kevin114514, OddImage, and JohnVictor for discussing about problems.
• Alexdat2000 for translating the problems into Russian.
• All of our testers: Tobo, A_G, shstyle., efishel, yorisou, el_programador, _istil, StarSilk, Cyber, xish, andreumat, GoogleBot, Tekor, SkyWave2022, LamaSalah, Error_Yuan, becaido, EzikBro, _LeMur_, MouadDidNotFail, JorgeIbanez.
• And You for participating!

The score distribution is as follows: $$$500 - 1000 - 1500 - 1500 - 2000 - (2000+2000) - 3000 - (3000+5000) - 4500$$$.

We hope you enjoy this round. Good luck and have fun!

UPD 1: Editorial

UPD 2: Congratulations to the top 10!

1. jiangly (Congratulations on being jiangly!!!)
2. tourist
3. gamegame
4. Benq
5. ecnerwala
6. arvindf232
7. ksun48
8. Egor
9. potato167
10. Um_nik (Congratulations on being the only one to solve Problem I!!!)

For the top 50 contestants, we will contact you soon for onsite participation.

Hellowo Codeforces o7

cry, larush, chromate00, Friedrich, Lilypad, and I are ebullient to welcome you to participate in Codeforces Round 998 (Div. 3) at Jan/19/2025 17:35 (Moscow time). We have cooked up $$$7$$$ problems to be solved in $$$2$$$ hours and $$$30$$$ minutes.

The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks. After open hacks all accepted solutions will be rejudged on successful hacks.

Note that the penalty for each wrong submission in this round is 10 minutes. Also, note the rule restricting AI use!!! If you are caught using AI in an unorthodox manner, you will be banished off the face of the earth (trust me).

Remember that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted participant of the third division, you must:

• take part in at least five rated rounds (and solve at least one problem in each of them)
• do not have a rating of 1900 or higher at any moment in time.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you (unless you register unrated).

We would like to orz the following individuals for making the contest possible:

• Vladosiya for coordinating our round.

• Our army of testuwuers: [VIP] awesomeguy856, [VIP] Dominater069, omeganot, Error_Yuan, Intellegent, -firefly-, amoeba4, 18o3, efishel, Edeeva, yoru_sacri, Abhishek_Srivastava, Vladosiya, macaquedev, DivinePunishment, Filikec, reirugan, pianapolataa, ETL, and Rahuldeb5,

• (MVP+++) MikeMirzayanov for developing the platform that will soon host Codeforces Round 1000.

UPD: Editorial

Hi, Codeforces!

I'm delighted to invite you to the best/second best/third best round of 2025 so far! Codeforces Round 997 (Div. 2) will be held on Jan/17/2025 17:35 (Moscow time). You will be presented with at least $$$6$$$ and at most $$$6$$$ problems, one of which might be divided into two subtasks, and $$$2$$$ hours to solve them.

Many of you may not believe it, but the problems were authored and written by nifeshe with a great help from maomao90. Moreover, I would like to thank:

• maomao90 for coordinating the round and helping with tasks ideas/preparation.

• Alexdat2000 for translating the problems to Russian.

• All of our testers: errorgorn, A_G, LipArcanjo, _istil, Markadiusz, Error_Yuan, Intellegent, mwen, Friedrich, flammifer, iLoveIOI, Rideris, DilshodbekX, chromate00, tibinyte2006 for, believe it or not, testing.

• MikeMirzayanov for the Codeforces and Polygon platforms.

• Bliznetc for playing chess with me.

• And You for participating!

The score distribution is as follows: $$$500-1250-1500-2000-2250-(2750+1250)$$$.

I hope you will find a non-empty subset of problems to be interesting. Good luck!

UPD 1: Editorial

UPD 2: Congratulations to the top 5!

Div. 1 + 2:

1. maspy
2. BurnedChicken
3. jiangly
4. antontrygubO_o
5. Sugar_fan

Div. 2:

1. OdtreeKing
2. saaaalty
3. STUDENT0
4. rainboy
5. MamurjonDeveloper

UPD 3: First solves:

A. 00:02:01 by hitonanode

B. 00:02:17 by pipi0818

C. 00:03:52 by Proof_by_QED

D. 00:13:53 by wishgoodluck

E. 00:18:06 by zdc123456

F1. 00:27:48 by peti1234

F2. 00:28:40 by rainboy

Всем привет!

Опубликовано расписание ИОИП 2025. Подробная информация на сайте https://nerc.itmo.ru/school/ioip.

Финал состоится 23 марта 2025 года. Эта олимпиада является личным зачетом "Олимпиады школьников по информатике и программированию" (ее командным зачетом является ВКОШП), которая входит в перечень олимпиад Российского совета олимпиад школьников и имеет 1 уровень. Таким образом, диплом этой олимпиады может давать льготы при поступлении в вуз.

На заключительный этап без дополнительного отбора приглашаются участники заключительного этапа ВКОШП 2024, обучающиеся в выпускном классе, все участники муниципального этапа ВсОШ в Санкт-Петербурге, обучающиеся в 11 классе, которые набрали на муниципальном этапе хотя бы 300 баллов.

Для остальных школьников пройдут два отборочных этапа: в 15:00 по московскому времени в воскресенье 2 февраля и в воскресенье 16 февраля 2025 года. Регистрация на сайте https://nerc.itmo.ru/school/io/registerIndividual.jsp.

Всем удачи!

Hello, Codeforces!

I'm pleased to invite you to open up the new year with Codeforces Round 996 (Div. 2) on Jan/12/2025 17:35 (Moscow time)! You will assist Florida Man through his whimsical adventures with $$$6$$$ tasks in the span of $$$2$$$ hours. The score distribution is as follows:

$$$\ \ \ \,$$$ $$$\ \ \ \,$$$ $$$\ \ \ \,$$$ $$$\quad\,$$$ $$$\quad\ $$$ $$$\ \ \ $$$

The problems were written and prepared by me, awang11. However, this round would not have been possible without:

• maomao90 for coordinating the round and carrying me in general;

• Alexdat2000 for translating the problems to Russian;

• all of our testers: imirdy, chromate00, Error_Yuan, HappyPacMan, Hyperbolic, ishaandas1, _istil, Friedrich, mohit458, NayemVai, priyanshu.p, raztun, sevlll777;

• MikeMirzayanov for the Codeforces and Polygon platforms;

• and You, for participating!

We hope you find that the problems are interesting, and that you earn your desired rating gains! or losses, if you somehow want that

UPD 1: The editorial is up! Hope you enjoyed the contest!

UPD 2: Congrats to the top 5!

Div. 1 + 2

1. Forested

2. maspy

3. potato167

4. A_G

5. Otomachi_Una

Div. 2

1. loK10

2. turgon314

3. BINYU

4. -ian

5. _Enana

First clears

A. aryan12, 00:00

B. ankan.2526, 00:03 (Div. 1 + 2: arvindf232, 00:03)

C. Sunflower233, 00:11 (Div. 1 + 2: DE_aemmprty, 00:07)

D. agaforces, 00:32 (Div. 1 + 2: Survivor_winner, 00:18)

E. myheartwaing, 01:50 (Div. 1 + 2: tute7627, 00:37)

F. N/A (Div. 1 + 2: maspy, 01:04)

Hello, Codeforces!

I'm excited to invite you to participate in MaraTON Challenge 1, our first marathon in collaboration with the TON Foundation. It's great to see our partnership with TON thriving and moving forward.

The challenge is brought to you by TON blockchain engineers, some of whom are community members. Special thanks to SpyCheese for preparing the problem!

The competition will run for three weeks, starting on Dec/23/2024 16:35 (Moscow time). Get ready to dive deep into the technical details of the blockchain world — it's worth it.

Winners will receive amazing prizes:

• 1st place: 8,000 USDT
• 2nd place: 5,000 USDT
• 3rd place: 3,000 USDT
• 4th–10th places: 2,000 USDT each
• 11th–20th places: 1,000 USDT each

Additionally, there will be bonus prizes for the leaders throughout the competition. Starting December 25th and continuing daily until January 13th at 13:35 (UTC), we will award bonus prizes to the top five leaders of the day:

• 1st place: 250 USDT
• 2nd place: 125 USDT
• 3rd place: 75 USDT
• 4th–5th places: 50 USDT each

Please note that these prizes will be distributed after full testing of all submissions made by 13:35 (UTC) on the respective day. The results are published here: https://mirror.codeforces.com/r/maraton-1-leadership-awards

Join the competition — it's truly something new and exciting on Codeforces!

* All payments will be made to a TON wallet. All payouts (including those for daily leadership) will be issued after the final results are announced.
* In case of ties in the leaderboard, the participant who first achieved the score will rank higher for prize distribution.
* Please note that this is an individual competition. Collaboration, discussing ideas, or using shared code is prohibited. Please adhere to the rules regarding the use of third-party code.

UPD: Here is the link to the table with the current progress on rewards for daily leaders: https://mirror.codeforces.com/r/maraton-1-leadership-awards