Hello, Codeforces!

Welcome to the ICPC Communication Routing Challenge powered by Huawei!

This challenge edition is very special, as it will be happening in conjunction with the ICPC World Finals! For those who are not participating in the finals — ICPC and Codeforces are offering a unique chance to compete during a 5-day Challenge Marathon and win amazing prizes from Huawei!

ICPC Challenge Marathon (open to public, unrated): October 9-14, 2021, 00:00 UTC:

This time we’re delighted to provide you with a future-oriented topic – routing algorithms for next-generation communication. During this Challenge we will provide you with a super-large inter-satellite optical network to properly plan message paths, to reduce communication latency and improve resource utilization. However, finding the optimal path in a network with limited resources is an NP-hard problem. Considering the physical constraints of optics and circuits, our algorithm faces greater technical challenges:

• How can we model and abstract device constraints and design algorithms in the most appropriate way?
• Is there an algorithm that takes almost the same time to calculate routes as the network scale increases?
• Is there any way to obtain the theoretical optimal solution in a short period for ultra-large networks?

We hope that these satellite communications challenge questions can help you understand the problems that Huawei's software algorithm researchers face every day. All the best!!!

Prizes

For 3-hours onsite ICPC World Finals Challenge Huawei will provide prizes to the winners in 2 groups of participants:

• Group 1: TOP 30 ICPC World Finalists, who participate individually:

  1st-10th place	HUAWEI MATE 40 Pro
  11th-20th place	HUAWEI MatePad Pro
  21st-30th place	HUAWEI WATCH 3 Pro

• Group 2: TOP 9 ICPC World Finals Coaches and Co-Coaches, who participate individually:

  1st-3rd place	HUAWEI MATE 40 Pro
  4th-6th place	HUAWEI MatePad Pro
  7th-9th place	HUAWEI WATCH 3 Pro

For 5 days online Challenge Marathon, Huawei will provide prizes to TOP 30 individual participants:

* The 1st place winner will get additional bonus in amount of 5000 USD. If the bonus cannot be transferred to the winner due to any reason, it may be replaced by a prize of the same value.

If the allocated Huawei Challenge prize cannot be delivered to your region for any reason it may be replaced by another prize of the same value (if no legal restrictions), at the discretion of the sponsor.

By participating in this Challenge, you agree to the Challenge Rules and Conditions of Participation

Good luck to all participants!

UPD: The contest duration has been extended to 5 days. The actual finish time is October 14, 2021, 00:00 UTC

Γεια σου (Hello), Codeforces!

Dremix10 and I are glad to invite you to the first Cypriot round Codeforces Round #747 (Div. 2) which will take place on Oct/08/2021 18:05 (Moscow time). Note the unusual start time of the round. As usual, this round will be rated for participants with rating lower than 2100.

Problems were created and prepared by Dremix10 and me. We tried to make them interesting, with short and clear statements. We hope that you will enjoy them!

I would like to thank:

• adedalic for amazing coordination of this round.

• Dremix10 for giving the first feedback about every problem I created.

• Markadiusz, cfalas, wxhtzdy, ijxjdjd, YouKn0wWho, PurpleCrayon, flamestorm, Shinchan01, rgnerdplayer, awoo, Hyperbolic, Nots0fast, UnstoppableChillMachine for testing the problems and providing useful feedback.

• MikeMirzayanov for Codeforces and Polygon platforms.

You will be given $$$6$$$ problems (and one subtask) and $$$2$$$ hours and $$$15$$$ minutes to solve them. Scoring distribution will be announced later.

Good luck and have fun!

UPD1:

Score Distribution: $$$500-1000-1500-1750-(1000-1500)-2750$$$

UPD2:

Editorial

UPD3:

Div2:

1. A-SOUL_Diana

2. End.

3. tuihuademing6

4. OguriCap

5. PATOLOVE

Div1 + 2:

1. SSRS_

2. tourist

3. 244mhq

4. hitonanode

5. A-SOUL_Diana

Hello, Codeforces!

First and foremost, we would like to say a massive thank you to everyone who entered and submitted their answers to the seven Kotlin Heroes competitions which were held previously: Episode 1, Episode 2, Episode 3, Episode 4, Episode 5: ICPC Round, Episode 6, and Episode 7.

Ready to challenge yourself to do better? The Kotlin Heroes: Episode 8 competition will be hosted on the Codeforces platform on 07.10.2021 17:35 (Московское время). The contest will last 2 hours 30 minutes and will feature a set of problems from simple ones, designed to be solvable by anyone, to hard ones, to make it interesting for seasoned competitive programmers.

Prizes:

Top three winners will get prizes of $512, $256, and $128 respectively, top 50 will win a Kotlin Heroes t-shirt and an exclusive Kotlin sticker, competitors solving at least one problem will enter into a draw for one of 50 Kotlin Heroes t-shirts.

Registration is already open and available via the link. It will be available until the end of the round.

The round will again be held in accordance with a set of slightly modified ICPC rules:

• The round is unrated.
• The contest will have 10 problems of various levels of complexity.
• You are only allowed to use Kotlin to solve these problems.
• Participants are ranked according to the number of correctly solved problems. Ties are resolved based on the lowest total penalty time for all problems, which is computed as follows. For each solved problem, a penalty is set to the submission time of that problem (the time since the start of the contest). An extra penalty of 10 minutes is added for each failed submission on solved problems (i. e., if you never solve the problem, you will not be penalized for trying that problem). If two participants solved the same number of problems and scored the same penalty, then those of them who had previously made the last successful submission will be given an advantage in the distribution of prizes and gifts.

If you are still new to Kotlin we have prepared a tutorial on competitive programming in Kotlin and Kotlin Heroes: Practice 8, where you can try to solve a few simple problems in Kotlin. The practice round is available by the link.

And last but not the least: two-time ICPC World Champion and winner of four previous Kotlin Heroes episodes Gennady tourist Korotkevich will be featured in a livecoding session, conducted by JetBrains, where he is going to show how to solve the problems from the Practice round, so you can learn how to use Kotlin in contests from the most famous competitive programmer in the world. The JetBrains Presentation and livecoding session from Gennady will be streamed on ICPC Live and Kotlin YouTube channel. The stream starts at 10 a. m. on the 2nd of October, Moscow time (UTC+3), you can join the stream by the link.

We wish you luck and hope you enjoy Kotlin.

Hello, Codeforces!

ICPC World Finals Moscow will begin on October 5, 2021 at 8:30 (UTC+3). We are thrilled to invite you to join the live broadcast of the main event of the year in the world of sports programming!

For the very first time in October 2021, Moscow will host the world’s most prestigious competition for young IT talents, the ICPC World Finals Championship. The last International Collegiate Programming Contest has hosted over 60000 students from 3,514 universities in 115 countries that span the globe. October 5 more than 100 teams will compete in logic, mental speed, and strategic thinking at Russia’s main Manege Central Conference Hall.

Some useful links:

• Official website of the ICPC
• Official world finals website
• Schedule of Events
• Live broadcast
• ICPC World Finals Mirror (Endagorion + Petr + tourist)
• Scoreboard
• Problem set

All available broadcast:

We wish good luck to all competing teams to have a great time spending, and to do the best to get amazing results!

صباحو (Good Morning), Codeforces!

I'm glad to invite you to Codeforces Round 746 (Div. 2), which will be held on Oct/03/2021 17:35 (Moscow time).

This round is rated for the participants with rating lower than 2100.

You will be given 6 problems and 2 hours to solve them. All problems were prepared by me and Bakry.

One of the problems will be interactive. So, it is recommended to read the guide on interactive problems before the round.

I would like to thank:

• antontrygubO_o, for a lot of things (awesome coordination, suggestion for one of the tasks, helping in preparation, rejecting only not interesting tasks, a lot of useful discussions).

• KostasKostil for one of the tasks and antontrygubO_o for preparing it.

• YahiaSherif, ZeyadKhattab, mahmoudbadawy, Uzumaki_Narutoo, _zaher_ for discussing and testing the problems.

• Our army of testers 244mhq, TripleM5da, Naseem17, Mohammad_Yasser, ZerooCool, compiler_101, TheSawan, IsaacMoris, Mohamed.Sobhy, AhmedEzzatG, Ahmed_AIansary, Evro, Sisy, G.A.T.C, mennafadali, Khater, It_Wasnt_Me, DAleksa, Samez, soba, O_E, AhmedZ, AshrafEzz, Urvuk3, Mo2men, Ahmad.houmani.

• MikeMirzayanov, for the amazing Codeforces and Polygon platforms.

The statements are short and we have tried to make the pretests strong. I encourage you to read all the problems.

For people who don't like stories, you will find all the stories written in italic you can skip them safely.

This is our first official round on Codeforces. We are sincerely looking forward to your participation. We hope everyone will enjoy it.

Good luck and see you in the standings!

UPD:

Score Distribution: $$$500$$$ — $$$1000$$$ — $$$1500$$$ — $$$2000$$$ — $$$2500$$$ — $$$(1750-1750)$$$

UPD1: Editorial is out!

UPD2: Winners

Div. 1 + Div. 2

1. LayCurse

2. SSRS_

3. qazsxdew

4. peti1234

5. dlalswp25

Div. 2

1. qazsxdew

2. CrTsIr

3. tsukigakirei

4. FangZeLi_AK_IOI

5. RiCHEPCPR

Hi Codeforces ଘ(੭*ˊᵕˋ)੭* ੈ♡‧₊˚!

We're delighted to invite you to COMPFEST 13 — Finals Online Mirror (Unrated, ICPC Rules, Teams Preferred) on .

All problems were written and prepared by hocky, steven.novaryo, rama_pang, JulianFernando, tzaph_, Panji, richiesenlia, Sakamoto, and markus_geger.

I would also like to thank:

• KAN for helping to host the mirror round;
• (AVM.Martin, Ace_02), Berted, ardan, wijayareynaldo, and bukanYohandi for testing the round locally and improved the problems in early phases;
• UWr Kobor 53 (w0nsh, kobor, Fly_37), Almost Retired (KAN, Um_nik, Ekler), and errorgorn for testing the round and their really useful feedbacks;
• Universitas Indonesia, all the local committees, administrators, and managers of the whole COMPFEST event;
• prabowo for observing the contest;
• fushar for the Judgels platform used in the official contest; and finally
• MikeMirzayanov for the great Codeforces and our lovely Polygon!
• Extra thanks for rama_pang and steven.novaryo for working hard night 🌚 and day 🌞 making sure the problems are well-prepared (the contest wouldn't exist without their hands).

The duration will be 5 hours, consisting of 13 problems. You can register individually, but teams are preferred. You may expect relatively easier problems than ICPC Regional Contests. You may code parallely with several computers with your teammates and use prewritten codes and templates.

COMPFEST itself is an annual event hosted by Universitas Indonesia. It is the largest student-run IT event in Indonesia and competitive programming contest is one of the competitions hosted.

We've put great effort into preparing this contest and we hope that you will enjoy it. See you! ありがとう~! 🐾

UPD: Editorial is out!!! Editowial UωU

Congratulations to our top 5!

1. leziren (jqdai0815, TLE, heuristica)
2. heno239
3. bubble (riantkb, nuip, mtsd)
4. gisp_zjz
5. We Won it 0 time (aarr, afterall, Amoo_Safar)

Hello, everybody!

We would like to invite you to participate in the Mirror of The ICPC World Finals Moscow Invitational Contest. The original contest was made for the teams who cannot come to The World Finals in Moscow. They were competing for the medals and glory. The Invitational contest has already passed and the results will be revealed on October 5th.

The mirror contest will be held by almost standard ICPC rules with 10 to 14 problems. The difference from the traditional ICPC format is that your team can use three computers instead of one. The problems are expected to be of The World Finals difficulty. Also, the round will be unrated!

The problemset was prepared by NERC Jury Team with the help of many other people. The chief judge is Roman elizarov Elizarov. The jury members are Pavel PavelKunyavskiy Kunyavskiy, Georgy kgeorgiy Korneev, Evgeny eatmore Kapun, Ilya izban Zban, Niyaz niyaznigmatul Nigmatullin, Vasiliy SirShokoladina Mokin, Daniil danilka.pro Sagunov, Gennady tourist Korotkevich, Oleg snarknews Hristenko, Egor Egor Kulikov, Borys qwerty787788 Minaev, Pavel pashka Mavrin, Mike MikeMirzayanov Mirzayanov, Anton Paramonov, Bruce bmerry Merry, Zachary Friggstad Friggstad, Jakub Wojtaszczyk, David Van Brackle, and myself. (I hope I haven't missed somebody. :P)

I hope you will like the contest! Good luck and have fun!

UPD: The editorial is available here.

Hello Codeforces!

CQXYM and I are glad to invite you to Codeforces Round 745 (Div. 1) and Codeforces Round 745 (Div. 2), which will be held on Sep/30/2021 13:15 (Moscow time). Note the unusual time of the round.

Each division will have 6 problems and 2 hours to solve them. All problems were written and prepared by CQXYM and me. The round will be rated for both divisions.

We would like to thank:

• Aleks5d for his excellent round coordination and many useful suggestions that greatly help with preparation.
• Monogon, voidmax, alexX512, ijxjdjd, wxhtzdy, makogon2907, 16204, Hemose, Hinai_Paulette, H4ckOm, 4qqqq, FBKdaisuki, kassutta, Mo2men and pkpawan for testing the round and providing useful feedback.
• MikeMirzayanov for great platforms Codeforces and Polygon.
• And you, for participating!

This is our first round, and great efforts have been put into preparing this round. Were you to kindly participate in this round, we would be very grateful and hope you will enjoy it.

Good luck!

UPD: Here are the scoring distributions:

Div. 1: $$$500$$$ — $$$1000$$$ — $$$1750$$$ — $$$2000$$$ — $$$3500$$$ — $$$3500$$$

Div. 2: $$$500$$$ — $$$1000$$$ — $$$1500$$$ — $$$1750$$$ — $$$2500$$$ — $$$2750$$$

And we would also like to thank Um_nik for testing the round.

UPD2: Editorial is out!

UPD3:

Winners

Congratulations to the winners:

Div1:

1. nutella_waxberry

2. maroonrk

3. Radewoosh

4. Karry5307_AK_NOI2025

5. hos.lyric

Div2:

1. _ywy_c_asm_

2. lpf666

3. Fuzen

4. leap_frog

5. OguriCap

Всем привет!

Сегодня я хочу представить вам новый проект Competitive Programming Hall of Fame, который уже доступен по адресу cphof.org

Немного истории

Довольно давно я обнаружил, что в Интернете нет единого источника информации, который содержал бы результаты международных чемпионатов по спортивному программированию. Более того, сайты старых соревнований постепенно отмирают, и найти важные детали становится сложно, а порой и вовсе невозможно. Поэтому я решил создать сайт под названием Competitive Programming Hall of Fame.

О проекте

Competitive Programming Hall Of Fame — это проект, созданный с целью сохранить историю международных чемпионатов по спортивному программированию. На этом сайте хранятся результаты финалов всемирных и региональных контестов. Под международным чемпионатом мы понимаем соревнование, состоящее из нескольких этапов, и доступное для участников из более, чем одной страны.

Проект на данный момент сфокусирован на международных соревнованиях, имеющих онсайт-финал, а также на менее крупных чемпионатах, в финал которых выходит до ста финалистов. Для каждого из участников на сайте есть страница-профиль со списком контестов, в которых он выходил в финальный этап, а также с таблицей Timeline.

На сайте все чемпионаты разделены на пять категорий: Worldwide Onsites (Major Competitions), Worldwide High School and Collegiate Onsites, Worldwide Online Championships, Regional Contests, и Local Contests.

Как можно помочь проекту

Вы можете помочь, предоставив информацию, которая отсутствует или указана неправильно на нашем сайте. Пожалуйста, воспользуйтесь для этого формой на странице cphof.org/contribute или же комментариями/личными сообщениями на Codeforces.

Мы будем особенно рады, если вы сможете найти и поделиться с нами информацией по одному из этих пунктов:

• Результаты любого международного чемпионата по программированию, который не представлен на сайте;
• Неверные данные на нашем сайте, несколько разных профилей для одного и того же человека (или наоборот, профили нескольких разных людей оказались склеены в один);
• Неправильное написание имён;
• Составы команд и призы за ACM-ICPC World Finals 2005 и более ранних;
• Таблицы результатов (с количеством сданных задач и штрафом) для ACM-ICPC World Finals 2009, а также до 1998 года включительно;
• Составы команд Google Hash Code и Challenge24 за любой год.

Благодарности

Выражаю благодарность aropan (clist.by), eduardische (stats.ioinformatics.org), kostka (kostka.dev), snarknews (snarknews.info), zibada (zibada.guru), неизвестному автору www.go-hero.net, MikeMirzayanov, а также всем авторам (Codeforces)-блогов со списками финалистов различных контестов за создание ценных ресурсов, которые разделяют цель сохранить историю международных чемпионатов по спортивному программировнию. Без них наш сайт не смог бы быть столь детальным. А ещё хочется сказать спасибо aropan, DAle, Romka и tourist за некоторые полезные советы перед запуском.

Всем привет!

Приглашаем Вас принять участие в Codeforces Round 744 (Div. 3) – раунд для третьего дивизиона, который состоится во 28.09.2021 17:35 (Московское время). Раунд был составлен совместными усилиями меня и MikeMirzayanov, и мы очень надеемся, что задачи вам понравятся и покажутся достаточно интересными.

Отдельно хочется поблагодарить MikeMirzayanov за помощь как в составлении, так и в разработке задач для раунда. Это второй Div. 3 раунд, в создании которого я принимаю участие, но только первый, в котором я готовлю задачи полностью, так что без его руководства я бы потратил на это гораздо больше времени.

Помимо этого отдельная благодарность nizamoff, andreumat, QAZZY, Vladosiya, CtrlAlt, vladmart, Igorjan94, okwedook, ashmelev и Aris за тестирование раунда и фидбек по задачам, а также Gassa и geranazavr555 за вычитку и корректировку условий – благодаря вам этот раунд стал заметно лучше, чем мог бы быть без вашего вклада. Ну и наконец, спасибо всем, кто примет участие в раунде! Раунд будет содержать от 7 до 8 задач и расчитан по сложности на участников с рейтингами до 1600, однако все желающие с рейтингом 1600 и выше могут зарегистрироваться на раунд вне конкурса.

Раунд пройдет по правилам образовательных раундов. Таким образом, во время раунда задачи будут тестироваться на предварительных тестах, а после раунда будет 12-часовая фаза открытых взломов. Мы постарались сделать сильные тесты, что, однако, не гарантирует, что фаза взломов будет безрезультатной.

Вам будет предложено 7-8 задач и 2 часа 15 минут на их решение. Штраф за неверную попытку в этом раунде (и последующих Div. 3 раундах) будет равняться 10 минутам.

Напоминаем, что в таблицу официальных результатов попадут только достоверные участники третьего дивизиона. Как написано по ссылке – это вынужденная мера для борьбы с неспортивным поведением. Для квалификации в качестве достоверного участника третьего дивизиона надо:

• принять участие не менее чем в двух рейтинговых раундах (и решить в каждом из них хотя бы одну задачу)
• не иметь в рейтинге точку 1900 или выше.

Независимо от того, являетесь вы достоверными участниками третьего дивизиона или нет, если ваш рейтинг менее 1600, то раунд для вас будет рейтинговым.

Всем хорошего настроения и удачи!

UPD: Выложен разбор задач!