Привет, Codeforces!

В Aug/17/2023 17:35 (Moscow time) состоится Educational Codeforces Round 153 (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, 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:

Harbour.Space University в партнерстве с Giga (Unicef) предлагают стипендию для получения степени магистра в сфере Computer Science and Front-end Development, а так же опыт работы.

Мы ищем различных кандидатов от junior до mid уровня:

Front-end разработчик:

Студенту на этой позиции придется тесно сотрудничать с разработчиком блокчейна и главным менеджером по продукту чтобы способствовать разработке и реализации пользовательских интерфейсов для прототипов компании на основе блокчейна. Они будут отвечать за перевод каркасных фреймов UI/UX в функциональные и визуально привлекательные веб-приложения, обеспечивая беспрепятственный пользовательский опыт. Студент будет сотрудничать с блокчейн и бэкенд разработчиками и дизайнерами для оптимизации производительности приложения. Они также будут участвовать в тестировании, отладке и поддержании базы исходных кодов. У стажера будет возможность получить практический опыт разработки интерфейса в контексте технологии блокчейна и внести свой вклад в миссию Giga по подключению школ к Интернету.

• Уверенное понимание HTML, CSS и JavaScript
• Знакомство с фронтэнд фреймворками и инструментами, такими как React или Vue.js.
• Навык решения задач, внимание к деталям и страсть к созданию интуитивно понятных пользовательских интерфейсов имеют важное значение

Full Stack разработчик:

• Интерес и опыт в разработке веб-приложений, информационных продуктов и OpenAPI
• Умение работать с облачными службами развертывания (предпочтительно Azure), конвейером Git и CI/CD, а также процессами развертывания.
• Приветствуется опыт работы с проектами с открытым исходным кодом
• Уверенное знание ML
• Опыт работы с инструментами визуализации данных, такими как matplotlib, ggplot, d3.js, Tableau
• Отличные коммуникативные навыки — невероятно важно описывать результаты для технической и нетехнической аудитории
• Большой опыт разработки программного обеспечения
• Практический опыт работы с инструментами обработки данных
• Способность решать задачи
• Аналитический склад ума и отличное деловое чутье
• Степень в области компьютерных наук, инженерии или смежной области приветствуется

Все успешные кандидаты будут иметь право на получение стипендии со стопроцентной оплатой обучения (29 900 евро в год), предоставляемой нашими партнерами.

ОБЯЗАТЕЛЬСТВА КАНДИДАТА

Обучение: 3 часа в день

За год обучения вы завершите 15 модулей (длительность каждого 3 недели). Ежедневная учебная нагрузка составляет 3 часа, плюс домашнее задание, которое нужно выполнить в свободное время.

Работа: 4 часа в день

Погрузитесь в профессиональный мир во время обучения. Вы будете учиться у лучших и с первого дня сможете применять свои новые знания на практике.

ТРЕБОВАНИЯ

• Опыт работы в отрасли
• Международная экспозиция
• Стремление к обучению
• Устойчивое развитие ключевой момент для вас
• Желание работать на общественную организацию

UPD: Разбор опубликован

Привет, Codeforces!

Мы рады пригласить вас принять участие в Codeforces Round 893 (Div. 2), который состоится 15.08.2023 17:35 (Московское время).

Обратите, пожалуйста, внимание на необычное время начала раунда. Этот раунд будет рейтинговым для участников, чей рейтинг ниже 2100.

Наш раунд был полностью подготовлен учениками ЛКШ (Летней компьютерной школы). Мы постарались подготовить по-настоящему интересные и креативные задачи. Вы можете ознакомиться с некоторыми из предыдущих раундов, подготовленных учениками ЛКШ: Codeforces Round 816 (Div. 2), Codeforces Round 815 (Div. 2),Codeforces Round #694,Codeforces Round #612,Codeforces Round #530.

Авторы и разработчики задач: Дарья arbuzick Грекова, Петр green_gold_dog Лосев, Ярослав Kihihihi Семенюк, Артем ArtAlex Алексеев, Антон NToneE Егоров, Федор FedShat Шатохин, Тимофей IzhtskiyTimofey Ижицкий, Егор salyg1n Салыгин, Владимир plagues Герасиков под руководством Евгения pakhomovee Пахомова

Мы очень благодарны

• преподавателям ЛКШ, которые внесли вклад в создание раунда: Кириллу kirill.kligunov Клигунову, Алексею daubi Васильеву, Антону stepanov.aa Степанову и Федору fastmath Ушакову

• тестерам за хорошие предложения по улучшению задач и полезные отзывы: KseniaShk, AndreyPavlov, glebustim, Semen07, Ooops_no, adventofcode, Sweezy, NToneE, Umi, DanilaOdesser, maomao90, Nikitun, a.stepanov281005, i_love_penguins, Kayot, LeoPro, exhausted, SomethingNew, AndrewPav, Dart-Xeyter, lgswdn

• Гимрану bashkort Абдуллину за просмотр всех задач и ценные советы по улучшению раунда

• нашему координатору IgorI за ценные советы и проявленное терпение

• KAN за помощь в подготовке раунда

• MikeMirzayanov и geranazavr555 за прекрасные платформы codeforces и polygon

У вас будет 5 задач и 2 часа на их решение. Мы рекомендуем вам прочитать все задачи. В раунде могут встретиться интерактивные задачи! Обязательно прочитайте этот пост.

Разбалловка: $$$500-1250-1500-2000-(1750+1000)$$$

Обратите внимание, раунд перенесен на 1 час. Время начала: 15.08.2023 17:35 (Московское время)

Мы надеемся, что вам понравятся подготовленные нами задачи!

Удачи!

UPD: Разбор

UPD 2: Поздравляем победителей!

Div. 2:

1. dong_liu

2. yydtq

3. wk______tzc

4. qwesda

5. Van_Dijk

Div. 1:

1. jiangly

2. neal

3. BucketPotato

4. kotatsugame

5. YocyCraft

First solves:

A. ball_of_wool

B. ecnerwala

C. nigus

D. jiangly

E1. grass8sheep

E2. yydtq

Hello, Codeforces.

We are happy to invite you to Codeforces Round 892 (Div. 2), which will take place on 12.08.2023 17:35 (Московское время). All of the problems are original and were prepared by a collective of authors, consisting of kristevalex, i_love_penguins, efimovpaul and me, induk_v_tsiane. This round will be rated for participants with a rating lower than 2100.

We would like to thank:

• Artyom123 for coordinating the round.

• maomao90, Umi, Qwerty1232 and Mangooste for GM testing.

• maks_matiupatenko, tiom4eg, ilyakrasnovv, sergeev.PRO, EJIC_B_KEDAX, Kihihihi, gmusya, zwezdinv, 74TrAkToR, Dominater069, TeaTime, antonis.white, nikuradze, satyam343, Noobish_Monk, AquaMoon, fishy15, meowcneil and green_gold_dog for Master and International Master testing.

• diskoteka, ArtAlex, MrEssiorx and makrav for CM testing.

• playerr17, dmikhalin, FelixDzerzhinsky, KiruxaLight, VolkovMA, Gornak40, Splatjov, v0s7er, arseny2606, Mr_Ell, qwexd and olyazyryanova for Expert testing.

• YakovLya and LinkCatList for Specialist testing.

• pazal for Newbie testing.

• And last but not least, MikeMirzayanov for the Codeforces platform and Polygon systems.

You will be given 6 problems and 2 hours to solve them. The score distribution is 500 — 1000 — 1250 — 1750 — 2250 — 3000.

I would like to also congratulate my cousin Max, who is turning 30 the day of the round. If you wish, you can write birthday wishes for him and I will pass them on.

UPD: Editorial

UPD 2: Congratulations to the winners!

Div. 2:

1. modulo998244353

2. botjiaxun

3. Tmath_OneLove

4. FengjianZhu

5. Alihan_8

Div. 1:

1. Geothermal

2. heno239

3. maspy

4. jiangly

5. Ormlis

Hello, my favorite community!

I’m in a hurry to tell you about a new event from our main sponsor — TON Smart Challenge #4!

An exciting 10 days contest that's open to both beginners and experienced FunC developers with a total prize fund of 30,000 TON begins on August 8th and lasts until August 18th, 23:59:59 UTC+4.

TON Smart Challenge #4 is designed to showcase the fundamental aspects of how smart contracts function in TON. Participants will have the opportunity to master complex cell manipulations, smart contract storage organization, comment handling, basic cryptography, and the logic of governance smart contracts through problem-solving.

To enter the challenge, simply register via the @toncontests_bot on Telegram. The bot will guide you through the registration process and keep you informed when the challenge starts, and the tasks are published. It will also help you submit your solutions as a legitimate participant.

More details about the contest and prize distribution one may find on the website.

But that’s not all the news!

In the early days of August was unveiled a new and improved TON Society.

TON Society, community of like-minded people united by the idea to contribute to the development of the TON ecosystem, has adjusted its philosophy and presents its improved version.

The mission of the upgraded community is to develop TON regional communities around the world, help enthusiasts organize offline meetings and attract local investors to work on TON projects.

To make this happen were established hubs in different regions worldwide:

• Europe
• SEA
• South Korea
• India

Builders and developers are welcome to join the TON Society and regional hubs.

Participating in TON Society means you’re aligning with the mavericks, forward-thinkers, the game-changers, and those who are shaping the world of TON.

Hello Codeforces!

We are pleased to invite you all to participate in Codeforces Round 891 (Div. 3), which will start on 07.08.2023 17:35 (Московское время).

The format of the event will be like any Div. 3 rounds:

• 6-8 tasks;

• ICPC rules with a penalty of 10 minutes for an incorrect submission;

• 12-hour phase of open hacks after the end of the round (hacks do not give additional points)

• after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated

• by default, only "trusted" participants are shown in the results table.

We encourage participants with a rating of 1600+ not to create new accounts but to participate unofficially.

Only trusted participants of the third division will be included in the official standings table. This is a forced 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 point of 1900 or higher in the rating.

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

Problems have been created and written by our team: FBI, Skillful_Wanderer, SashaT9 and Pa_sha.

We would like to thank

• MikeMirzayanov for creating Codeforces and Polygon.

• Vladosiya for coordination.

• nigus, YocyCraft, lis05, Nazar, welleyth, pavlekn, senjougaharin, Vladithur, DJeniUp, volochai, eggag32, moonpie24, shell_wataru, Kalashnikov, Bogdan1110, ksu_, zamong_juice, myav, sonyalytv for testing the round and making it better.

Good luck!

UPD: There was an error on problem F. We fixed the tests and rejudged solutions . We apologize for that. It only affected a few people whose solutions passes all tests now. Also some hacks were already added to the tests and broke some of solutions.

UPD2: Editorial

Hi, Codeforces!

Alexdat2000, Igorfardoc, and I are pleased to invite you to our Codeforces Round 890 (Div. 2) supported by Constructor Institute, which will be held on Aug/05/2023 17:35 (Moscow time). This round will be rated for participants with a rating lower than 2100.

We would like to thank:

• errorgorn for coordinating the round.
• Umi, maomao90, thenymphsofdelphi, Dominater069, Mike4235, valeriu, irkstepanov, zengminghao, Gheal, DeMen100ns, FEDIKUS, thanhchauns2, MinaRagy06, Java, xudian, madlogic, squishybanana04, stefanbalaz2, kobebryan9, Murinh0, IlyinAD, zamong_juice, Pemguimn, the_hyp0cr1t3, STommydx, peshkoff, AndZhi, revelcoS, Valenz, and tibinyte for testing the round and providing useful feedback.
• MikeMirzayanov for Codeforces and Polygon.

You will be given 5 problems, one of which is divided into two subtasks, and you will have 2 hours to solve them.

One of the problems will be interactive, so please read the guide for interactive problems if you are not familiar with it.

The score distribution is 500 — 750 — 1250 — 2000 — (1500 — 1500)

UPD: Tutorial

UPD2: Congratulations to the winners!

Div. 2:

1. AMDAM
2. Aoi_Minoa
3. baojiaopicua
4. Valaki2
5. JCY_

Div. 1:

1. neal
2. maspy
3. A_G
4. AmazingTalker_Frank
5. heno239

We are thrilled to share some exciting news with you! We are teaming up with our partner, Constructor Institute in Schaffhausen, Switzerland, to bring you an amazing opportunity: a round supported and organized in collaboration with Constructor Institute, where you can explore Master's programs in Switzerland. Now we pass the floor to our partner.

Hello, Codeforces community!

Constructor Institute in Schaffhausen (Switzerland) is pleased and proud to have the opportunity to support the round on Codeforces. We invite you to participate in it!

If you are passionate about studying in Switzerland and pursuing a Master’s degree, we encourage you to fill out the form to initiate the application process and scholarship interview. Our Institute representatives will be in touch with you to guide you through the next steps.

We offer two Master programs, both taught in English, with flexible duration of 1.5 or 2 years full-time:

• MSc in Computer Science, Software Engineering, and Leadership
• MSc in Quantum Software Engineering, and Computer Science

Our Master's programs open doors to a world of opportunities. Many of our students have secured high-profile roles in multinational companies in Switzerland and across the globe. Additionally, our programs also serve as an excellent preparation for Ph.D. research in fields such as software engineering, cybersecurity, artificial intelligence, and other advanced topics.

​​We understand that financing your education can be a concern, and to support your journey, we are offering the following scholarships:

• Tuition waiver scholarships — 20,000 CHF per year, covering the cost of tuition fees.
• Full scholarships — 20,000 CHF per year, covering the cost of tuition fees, along with a monthly stipend of 2,000 CHF to assist with living expenses in Schaffhausen.

Both scholarships are non-repayable, providing you with financial peace of mind.

To learn more about Constructor Institute and its programs, visit our webpage.

Eligibility for the programs and its available scholarships:

• You have obtained or you will obtain a Bachelor’s degree in Computer Science, Software Engineering, Physics, or a related field before the program starts.

To express your interest in this opportunity, please complete the form:

We wish you good luck in the competition and enjoy solving the problems.

Hello, Codeforces.

It's scary to think about it: there are already almost 1800 rounds in the list of past contests!

I started adding a filter to the table with these rounds. Right now, you can already filter by some of the types of rounds. Here's what I've supported:

• Div. 1
• Div. 2
• Div. 3
• Div. 4
• Div. 1 + Div. 2
• Educational Rounds
• CodeTON Rounds
• Globals
• Kotlin Rounds
• VK Cup Rounds
• Long Rounds
• April Fools

Of course, I might have forgotten some types of contests. Please remind me if I missed anything. We should pay attention only to types where we have conducted several contests of that type.

I plan to expand this filter by adding more settings. Perhaps it would be good to filter by the condition "has at least one submission in this contest" (or those for which no submissions at all). What do you think?

What else would you suggest adding?

P.S. Here is how it looks on the website (some intermediate version, some options may be missing).

I don't think comments like "you use X in model solution, author, are you an idiot?", "f**k you and your problems, they are shit" and such should be normal on Codeforces, especially when written by someone high-rated and/or respected in the community. I also don't think this kind of behavior should be normal towards regular users.

I know that sometimes contests can be frustrating. Sometimes it is the participant's fault, sometimes it is the problemsetter's fault, sometimes it just happens without anyone being guilty of that. And I understand that in some cases, the criticism the author receives is fair and well-deserved.

But there is a fine line between criticism, saying that you didn't like the problems, and hurling insults against the author. The former two are acceptable (and sometimes even needed, because authors have to improve and learn from their mistakes); the latter one, in my opinion, should not be acceptable.

It's not like we can ever get rid of offense and hatred completely; there will always be people who want to take it out on the community as a whole or someone specific. And if I created a blog for every time I saw an insult hurled towards me or some other member of the community, my account would already be banned for spamming. But I think that the comments like the one linked in the first paragraph are especially dangerous and need to be dealt with.

Codeforces community is biased towards people with high rating and people who do something for the website. And this is sometimes a good thing; but it can also make people think that if a high-rated participant and a problemsetter allows himself (or herself) to be rude and offensive, then it is acceptable, and they are allowed to do it as well. That's why cases like this one are especially bad.

We can never get rid of offense and hatred, but please don't make it something normal. Everyone should be responsible for what they are saying or writing, but if your word has some weight in the community, then it also means some additional responsibility for you. Please don't make people think that insulting the author (or anyone else, for that matter!) is perfectly reasonable and fine — I doubt you will like the results of that.

UPD: It looks like the focus of the comment section has shifted towards discussing how to give constructive feedback to the problemsetters. This is certainly one of the points of the blog, but the main thing I wanted to state was that insults against anyone should not be acceptable. It's just that the problemsetters usually get the most of the hatred on CF, so it's much easier to find the examples of that. But this behavior towards regular users should not be allowed either.

UPD2: Initially, there was a link to the comment which caused me to write this whole blog (a comment by a high-rated user and a problemsetter when he openly called another problemsetter retarded because of some details of the solution). I wanted to show it as a clear example, but it was not the right thing to do.

To the person whose comment I used as an example (if you're reading this): I apologize, I shouldn't have made it seem like you're the culprit, and I didn't understand the consequences of my blog fully. I know that you have openly admitted your mistake, and I admire you for that. If the fact that I've used you as an example made you feel awful, or made some other people call you out — I am terribly sorry.

Ciao, Codeforces! We're glad to invite you to take part in Codeforces Round 889 (Div. 1) and Codeforces Round 889 (Div. 2), which will start on Jul/29/2023 17:35 (Moscow time). You will be given 6 problems and 2 hours and 30 minutes to solve them in both divisions.

• One of the problems will be divided into two subtasks.
• One of the problems will be interactive, so please read the guide for interactive problems if you are not familiar with it.

The problems were authored and prepared by akifpatel, dario2994, Kaey and me.

We would like to thank

• dario2994 for his energetic coordination;
• Alexdat2000 for Russian translation;
• Vladithur, errorgorn for VIP testing;
• ALeonidou, antontrygubO_o, buffering, cry, emorgan, jamesbamber, MatteoArcari, MrBrionix, MyK_00L, pwned, zamong_juice for testing;
• MikeMirzayanov for creating Codeforces and Polygon.

Score distribution:

• Div. 1: $$$(750 + 750) - 1500 - 1500 - 2000 - 2750 - 3250$$$
• Div. 2: $$$500 - 1000 - (1250 + 1250) - 2500 - 2500 - 3000$$$

We hope you'll like the problemset!

Update 1: the editorial is out.

Update 2: congratulations to the winners!

Привет, Codeforces!

В 27.07.2023 17:35 (Московское время) состоится Educational Codeforces Round 152 (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, Михаил awoo Пикляев и Максим Neon Мещеряков. Также большое спасибо Михаилу MikeMirzayanov Мирзаянову за системы Polygon и Codeforces.

Удачи в раунде! Успешных решений!

UPD: Разбор раунда опубликован.