Привет, Codeforces!

Я очень рад пригласить вас на Codeforces Round #843 (Div. 2), который пройдет в 10.01.2023 14:15 (Московское время). Этот раунд будет рейтинговым для участников, чей рейтинг ниже, чем 2100.

Моя искренняя благодарность:

• KAN и Aleks5d за выдающуюся координацию раунда!

• Wind_Eagle, BaluconisTima, kartel и Aleks5d за идеи задач для раунда, а также Wind_Eagle, BaluconisTima, kartel, VEGAnn и Vladik за разработку задач.

• andrew, gepardo, 244mhq, vilcheuski — остальную команду авторов области, без которых этот раунд бы не состоялся.

• BaluconisTima за прекрасные картинки, дополняющие все задачи.

• MikeMirzayanov за платформы Codeforces и Polygon.

• Вам, за то, что участвуете в этом раунде.

У вас будет 2.5 часа на решение 6 задач, одна из которых будет разбита на простую и сложную версии. Раунд основан на задачах первого тура третьего этапа республиканской олимпиады по информатике в Беларуси. Просьба всех белорусских школьников, участвовавших в третьем этапе, воздержаться от участия в раунде и обсуждения задач публично до конца раунда.

Я надеюсь, вам понравится раунд!

Тестировали раунд: MathBoy, FairyWinx, nnv-nick, K1ppy, olya.masaeva, Septimelon, PavelKorchagin, 4qqqq, kova1.

Разбалловка: (500+1000)-1000-1500-2000-2000-2500.

UPD. Разбалловка была изменена: (500+500)-1000-1500-2000-2250-3000.

UPD2: Поздравления победителям!

Проголосуйте за вашу любимую задачу!

Задача А: Садовник и капибары

Задача B: Садовник и массив

Задача C: Интересный ряд

Задача D: Дружелюбные пауки

Задача E: Уравнивание людей

Задача F: Лаборатория на Плутоне

UPD3: Наконец-то готов разбор: тык сюда

Привет, Codeforces!

В 08.01.2023 17:35 (Московское время) состоится Educational Codeforces Round 141 (Rated for Div. 2).

Продолжается серия образовательных раундов в рамках инициативы Harbour.Space University! Подробности о сотрудничестве Harbour.Space University и Codeforces можно прочитать в посте.

Этот раунд будет рейтинговым для участников с рейтингом менее 2100. Соревнование будет проводиться по немного расширенным правилам ICPC. Штраф за каждую неверную посылку до посылки, являющейся полным решением, равен 10 минутам. После окончания раунда будет период времени длительностью в 12 часов, в течение которого вы можете попробовать взломать абсолютно любое решение (в том числе свое). Причем исходный код будет предоставлен не только для чтения, но и для копирования.

Вам будет предложено 6 или 7 задач на 2 часа. Мы надеемся, что вам они покажутся интересными.

Задачи вместе со мной придумывали и готовили Адилбек adedalic Далабаев, Владимир vovuh Петров, Иван BledDest Андросов и Максим Neon Мещеряков. Также большое спасибо Михаилу MikeMirzayanov Мирзаянову за системы Polygon и Codeforces.

Удачи в раунде! Успешных решений!

Также от наших друзей и партнёров из Harbour.Space есть сообщение для вас:

Привет, Codeforces!

Мы рады объявить о втором буткемпе по программированию «Hello Muscat 2023», продолжении серии буткемпов «Hello», организованном Harbour.Space University в сотрудничестве с PhazeRo, Gutech, UK Oman Digital Club, Leagues of Code, Gutech CS Club и Codeforces!

Довольно впечатляюще, не так ли? Пришло время глубже погрузиться в мир соревновательного программирования с 8-дневным интенсивом Hello Muscat 2023. Он будет проходить в Маскате, Оман, и онлайн с 8 по 16 марта 2023 года, доступны оба формата участия.

Наш тренерский состав сочетает в себе талант и опыт, в нем участвуют чемпионы мира ICPC, победители и финалисты, а также легендарные имена из области соревновательного программирования: Михаил Мирзаянов MikeMirzayanov, Егор Дубовик 244mhq, Артем Плоткин Rox, Максим Обозный MaksymOboznyi и Николай Будин budalnik.

Буткемп будет разделен на три дивизиона:

• Дивизион A. станет зеркалом Петрозаводского лагеря программирования. Подходит для команд, которые уже прошли квалификацию на Финал ICPC или стремятся к этому.
• Дивизион B. Разработан, чтобы помочь командам подготовиться к следующему сезону региональных соревнований ICPC. Подходит в качестве введения для команд и студентов, которые только начинают свой путь в мир ICPC и соревнований по программированию в целом.
• Дивизион C. Предназначен для новичков в мире соревновательного программирования.

Типы участия: очное и онлайн

Мы считаем, что участие в нашем буткемпе должно быть доступно для всех команд, где бы они ни находились, и именно поэтому мы сделали очную и онлайн-формы участия. Скидка 20% на раннее бронирование предоставляется университетам и участникам, которые зарегистрируются и оплатят до 31 января 2023 года.

• Очное:

Цена: 1500 € — 1200 €

Что включено: обучение, контесты, доступ к записям лекций, проживание в течение 9 ночей в 4-звездочном отеле Mysk, завтрак и обед, трансфер из гостиницы к месту проведения буткемпа каждый день, развлечения и приветственный подарок.

• Онлайн

Цена: 100 € — 80 €

Что включено: обучение, контесты и доступ к записям лекций.

Удачи в раунде,

Harbour.Space University Team

UPD: Разбор опубликован

Greetings, Codeforces!

We are excited to announce TypeDB Forces, which will take place on Sunday 29th of January – our first competition of 2023, with hopefully many more to come! We’re from Vaticle, and we’re the creators of TypeDB & TypeQL. TypeDB is a strongly-typed database, and we are building a team of world-class engineers to work on next generation database architectures, language compilers, type systems, reasoning engines, IDEs, and cloud infrastructures. Top scorers will earn cash rewards and swag, but we’re most excited to invite all the top performers of this round, from anywhere and everywhere around the world, to interview with our team and join our organisation!

Cash and Swag Prizes

• 1st place: 500 Euros
• 2nd place: 250 Euros
• 3rd place: 100 Euros
• Top 50: TypeDB hoodie, t-shirt and stickers
• Random 50 of 51-250: TypeDB t-shirt and stickers

About Vaticle & TypeDB

Vaticle is a team of people driven to empower engineers to solve complex problems. We are the creators of the strongly-typed database, TypeDB, and its query language, TypeQL. TypeDB is a strongly-typed database with a rich and logical type system. TypeDB empowers you to solve complex problems, using TypeQL as its query language. TypeDB provides a strong type system for developers to break down complex problems into meaningful and logical systems. Through TypeQL, TypeDB provides powerful abstractions over low-level and complex data patterns. From financial analytics to drug discovery, cyber threat detection to robotics disaster recovery,TypeDB empowers engineers around the world to tackle a higher order of complexity in data and knowledge.

We've built a pioneering developer community of 13,000+ engineers, spread over 20 countries, and counting. To continue pursuing this vision, we need to build a team of individuals who are not just the best and brightest in what they do, but are also driven by a strong sense of purpose and compassion for the world. You can learn more about the roles we’re hiring for at vaticle.com/careers.

You can find out more about our work from our website and GitHub pages.

Hi Codeforces!

Igorfardoc, Vladithur, Alexdat2000, GlowCheese, DeMen100ns, SPyofgame and me (spelling "thanh-chau-n-s-2") are delighted to invite you to participate in Codeforces Round #842 (Div. 2). This round will be rated for all participants with a rating lower than 2100.

• Start time: Jan/05/2023 17:35 (Moscow time)
• Duration: 120 minutes.
• Number of tasks: 6.

Special thanks to:

• errorgorn for his wonderful coordination.
• Vladithur for providing wonderful problems.
• Alexdat2000 for testing and translating our statements.
• Vip testers: Valenz, who spotted some critical issues in the problemset.
• Alexdat2000, Igorfardoc, SPyofgame, GlowCheese, DeMen100ns for helping us in some different phases of preparing the problem set.
• All-time mighty red cyan testers: gyh20, Chenyu_Qiu, xiaoziya, feecIe6418, Little09, ShmilyTY, thenymphsofdelphi, neko_nyaaaaaaaaaaaaaaaaa, LastDance, tfg, Andreasyan, generic_placeholder_name, Mangooste, BucketPotato.
• Other testers: darkkcyan, maomao90, tibinyte2006 (absolutely fake true color), Gheal, bugdone, ntherner, satyam343, alecs, 1DWalker, aineee, nyagami, vangtrangtan, hydroshiba, E404_Not_Found, DMCS, Duy_e, LetterC67, Ignr_h31, TrendBattles, kodomotachi.
• Other people for some reason cannot participate officially in this round: KasenIbaraki, LeCaToX, dinhsangBKA, Hungconmk, antontrygubO_o, RedMachine-74, ShuiLaoshi, Qingyu, alexxela12345, FireGhost.
• MikeMirzayanov for amazing platforms Codeforces and Polygon.
• Last but not least, you for participating and then being rage while implementing some 200 lines of code.

Edit: there will be $$$2$$$ packages for two participants in Vietnam, the highest score and the luckiest. You have to set your region to Vietnam to be qualified.

The score distribution is $$$500-1000-1500-1750-2250-3250$$$.

Hope to see you in the final standings!

Editorial is out.

Congratulations to the winners:

And the first solver for each problem:

Hi everyone!

I am happy to announce the Osijek Competitive Programming Camp that is scheduled to happen on 18-26 February 2023 in Osijek, Croatia. The camp is hosted by the Department of Mathematics at J. J. Strossmayer University of Osijek and is brought to you by the organizing team of adamant (that's me!), -is-this-fft-, mblazev, Tomx and antontrygubO_o.

The camp is inspired by various competitive programming camps that we attended during our active years in ICPC, and is aimed to help college students prepare for ICPC regional contests and finals. The camp will consist of 7 ICPC-style contests and 2 days off.

Up until now, most top competitive programming training camps have been organised in Russia, or by Russian entities. Due to the current situation in the world, attending such camps is not possible or desirable for a large number of participants, and we hope to offer a European alternative to Russian camps.

This is the first edition of the camp, and we all are very excited about it and hope that we may see you soon!

Details

Participation fee for onsite participants is 150€ per person. It does not include regular meals, travel or accommodation.

If you want to participate, but are unable to come onsite, we offer a reduced fee of 100€ per person for online participation. It is also possible to reduce fees individually if you are unable to attend some of the contests (e.g. because of the overlap with SWERC).

We support and empathize with those affected by the ongoing war in Ukraine, therefore we offer a 100€ discount for affected individuals and teams affiliated with Ukrainian institutions. In other words, the fees would be 50€ and 0€ per person for onsite and online participation correspondingly.

The expected starting time for the contests is 10am CET. For online participants, it is still a preferred starting time, but if it is not an option for you, we will also offer an opportunity to compete virtually within 24 hours after the main window is over.

Participants

If you are interested in participating, please fill the form here.

We ask you to register before February 10 if you want to participate online and before February 4 if you want to participate onsite.

If you want to participate onsite, especially if you require visa support, we would urge you to register as soon as possible, as visa processing may take 30+ days.

Also, if your university has a lively ICPC community that may be interested in attending the camp, and you have some contacts of people in charge (e.g. coaches) we would highly appreciate if you could fill the form here, so that we can send an invitation. Thanks!

Problemsetters

We'd like to praise the authors of the contests for the camp:

• jqdai0815 — a guy who changed CF username every year and labeled the contest by prime numbers.
• conqueror_of_tourist — ICPC 2022 world finalist. Codeforces LGM in Python.
• antontrygubO_o — IMO 2017 gold medalist, NAC 22 winner, contest coordinator, Codeforces LGM.
• Savior-of-Cross — ICPC 2023 world finalist.
• rivalq — Codeforces grandmaster, ICPC 2021 and 2022 world finalist.
• Adam_GS — Codeforces grandmaster, EJOI 2021 gold medalist.
• ToxicPie9 — ICPC 2021 world finalist.
• adamant — a maintainer of cp-algorithms.com, author of nearly 50 competitive programming problems.

Sponsors

Last but not least, we would like to say special thanks to our sponsors, who make the camp possible:

If you are interested in sponsoring next editions of the camp or have any questions, please feel free to reach out at [email protected].

Finally, we would also like to thank Codeforces for guidance and promoting this announcement to the main page, eolymp for providing us an online judge for the contests and the Department of Mathematics at J. J. Strossmayer University of Osijek for all their organizational support and providing us a physical location to conduct the camp.

Hello Codeforces!

I am pleasured to invite you to take part in Hello 2023, which will take place in Jan/03/2023 17:35 (Moscow time)!

This round consists of $$$8$$$ tasks waiting for you to solve in $$$150$$$ minutes, and will be rated for everyone!

As an author, please allow me to express my sincere thanks to:

• dario2994, for being responsive, his amazing guidance, helping me prepare one of the problems and his truly wonderful coordination!
• KAN, for rechecking and translating the round!
• wxhtzdy, for proposing rejected tasks and discussing every problem with me
• Giove, for a problem idea which fits a gap.
• Um_nik, gamegame, JovanB, Marko, cip999, nweeks, NemanjaSo2005, Sofija06, Fikuss, badlad, Jovan08, for providing valuable feedback and submissions during testing!
• MikeMirzayanov, for great platforms Codeforces and Polygon!

I hope you enjoy our problems and have a wonderful $$$2023$$$!

UPD1: New score distribution is $$$500 — 750 — 1250 — 1500 — 2250 — 2250 — 2750 — 4000$$$.

UPD2: Editorial is out!

UPD3: Congratulations to the winners!

1. Benq
2. tourist
3. heuristica
4. hitonanode
5. jiangly_fan
6. jiangly
7. duality
8. maroonrk
9. Maksim1744
10. DearMargaret

UPD4: Also, congratulations to the first solves of each problem!

1. Geothermal with 187728121
2. tourist with 187728792
3. tourist with 187733377
4. MEGAcrusher5000 with 187739126
5. tourist with 187755451
6. tourist with 187775898
7. TLEwpdus with 187757570
8. heuristica with 187815792

Hello, Codeforces.

It's time to take stock of last year. Shall we begin? And we are happy to sum up the results of the last season of Global Rounds. We announce the results!

We remind you that the global rounds are a joint initiative of XTX and Codeforces.

We hold 6 such rounds per year. All of them are open to both divisions. At each such round, 50 brand T-shirts were handed out, and we are happy to give T-shirts to all problem authors.

The prizes for the 6-round series are:

• In each round top-100 participants get points according to the table.
• The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
• The best 20 participants over all series get sweatshirts and place certificates.

Hello, Codeforces!

The year 2022 is finally coming to an end. Let's be clear. It's been a terrible year. Tomorrow I will make a wish, and you can easily guess which one.

I am writing these lines, and in a few minutes the Good Bye 2022 round will begin. And this inspires optimism and even pride in the community. Despite all these difficulties and troubles, we make rounds together and participate in them. Let's be grateful. And for this, let's say symbolic thanks to 2022 and a lot assistants: coordinators, problem writers, testers, participants and sponsors. We are many and we are together.

Can I have a little more detail on the Codeforces team?

Let me separately say thanks and words of admiration for the work of the coordinator of coordinators KAN and the senior developer geranazavr555. Both of you bring a lot to Codeforces, but your activity is not always noticeable. We appreciate it. Thank you!

I send thanks to Una_Shem: in the difficult conditions of broken global logistics, you do a lot so that the gifts are delivered to the winners, and the authors receive their reward.

Thanks to unreal.eugene for contributing to the development and kuviman for helping with setting up ci and other pipelines.

Who I will not say thank you to, it's cheaters! Ugh, to be like that. Please stay in 2022.

I'd like 2023 to be the year we regret leaving exactly one year from now.

Please make us happy!

Make our wishes come true.

* Image by ligrenok.

"It's been a long time since I came here, and I've really been through a lot." Koxia muses as she chatted idly with Mahiru.

Now that the Winter Festival is approaching. Among the flash of fireworks, in the chimes of the New Year, what is waiting for them to encounter?

Armed with girlish courage, they stepped onwards.

Hello Codeforces!

We (Nanako, m_99, huangxiaohua, SteamTurbine, triple__a, Nezzar) are very pleasured to invite you to take part in Good Bye 2022: 2023 is NEAR, which will take place in Dec/30/2022 17:35 (Moscow time)!

This round consists of 8 tasks waiting for you to solve in 150 minutes, and will be rated for everyone!

On behalf of the author team, please allow me to express our sincere thanks to:

• errorgorn, for useful guidance and brilliant advice during the coordination!
• KAN, for rechecking and translating the round!
• ak2006, tolbi, Tlatoani, gisp_zjz, Roundgod, Kaibad, xzm2024, Frozencode, woruo27, ayhan37, compute, muoshuo, conqueror_of_tourist, googol_S0, zengminghao, ntherner, manish.17, cuzperf, tibinyte2006, JuanPabloAmezcua, for providing valuable and constructive feedback during testing!
• 1tTx__, for the exquisite illustration!
• MikeMirzayanov, for great platforms Codeforces and Polygon!
• you and everyone, for participating and making this round have extraordinary significance!

This round is supported by NEAR. The participants in the top 2047 places will receive prizes as follows:

• Ⓝ 1024 for the first place
• Ⓝ 512 for the 2-3 places
• Ⓝ 256 for the 4-7 places
• ...
• Ⓝ 1 for the 1024-2047 places

Score distribution will be announced soon.

Besides the regular editorial, materials to be public after the round will also include the Chinese statement and the Chinese editorial.

We hope you enjoy our problems and say Goodbye to your 2022 happily!

UPD1: Score distribution is 500 — 750 — 1250 — 1500 — 2000 — 2500 — 3250 — 4000.

UPD2: Congratulations to the winners!

1. Benq
2. maroonrk
3. Radewoosh
4. Um_nik
5. tourist
6. ksun48
7. ecnerwala
8. aaaaawa
9. DearMargaret
10. jiangly

Thanks all for joining!

UPD3: The editorial is available.

UPD4: The Chinese statement and the Chinese editorial have been added into the contest attachments.

Hello, Codeforces!

The Programming Club, IIT Indore is proud to present the 8th edition of its flagship event, Divide By Zero — Codeforces Round #841 (Div. 2) and Divide By Zero 2022, under the annual code-fest, Euristica'23.

You can check some of the previous editions of Divide By Zero prepared by us : Codeforces Round #399 (Div. 1 + Div. 2), Codeforces Round #474 (Div. 1 + Div. 2), Codeforces Round #714 (Div. 2).

The contest will take place on Dec/27/2022 17:35 (Moscow time). This round will be rated for all participants with a rating lower than 2100.

People who had a great contribution to making this round possible:

• Problems were authored by nishkarsh, ka_tri and me.

• sksusha8853, Phantom_Deluxe, Anurag203, nishu2002, hk2102, krishanu21saini and somyamehta_24 made a great contribution to the problemset.

• Thanks to ajit, awoo, NemanjaSo2005, Nahian9696, Qg3, CARBINE, TomiokapEace, maomao90, MasterRayuga and prvocislo for testing the problems.

• Thanks to adedalic for wonderful coordination and for giving great advice throughout the round.

• MikeMirzayanov for Codeforces and Polygon platforms.

You will be given 6 problems, and 2 hours to solve them. The points distribution will be updated later.

UPD1: Score distribution is 500 — 1000 — 1500 — 1500 — 2000 — 2750

UPD2: The editorial is up.

PRIZES: Twenty T-shirt will be given to:

• Top 10 Indian Participants

• Random 10 from top 100 (rank 11-100) Indian participants

Hope you guys enjoy the contest! See you on the leaderboard :P

About Euristica

Euristica is the annual flagship programming event of The Programming Club of IIT Indore. As part of Euristica, we conduct a variety of online competitions spanning different programming domains. These events are open and free for all, and there will be exciting prizes and goodies for the winners.

Head over to our website to find out more about the competitions.

UPD3: Here is the list of winners who won T-shirts. We will contact you guys soon. Congrats!

Top 10 Indian Participants

• socho
• kshitij_sodani
• rivalq
• aryanc403
• satyam343
• meme
• shadow9236
• JrNTR
• iLLusio
• ShlokG

Random 10 from top 100 (rank 11-100) Indian participants

• yash_daga
• vineeth_kada
• GoatTamer
• Yomapeed
• killer_god
• orientor
• milind0110
• Chimpanzee
• mayankfrost
• hsrb

We have uploaded the link to the code for generating random numbers and ranklist here.