Приглашаем учащихся 7-11 классов из России и иностранных государств проявить себя в Олимпиаде по информатике «Innopolis Open».

Этапы проведения олимпиады:

Отборочный этап

Состоит из двух независимых отборочных онлайн-туров, продолжительность каждого 5 часов. В рамках него участникам предлагается по 4—5 задач по информатике.

• 1-й отборочный тур: 22 ноября 2020 г. 10:00 — 15:00 МСК
• 2-й отборочный тур: 13 декабря 2020 г. 15:00 — 20:00 МСК

Участник может пройти оба тура, тогда в отборе будет учитываться лучший результат по итогам двух туров. Победители и призеры Innopolis Open по информатике 2020 приглашаются на заключительный этап без отбора.

Отборочный этап также является отбором на Зимнюю школу олимпиадной подготовки по информатике 12—19 февраля 2021.

Финал

20—21 февраля 2021 г.

Формат проведения (очно или заочно) заключительного этапа остается под вопросом. В случае очного формата финал будет распределен на нескольких площадках по России и другим странам. Главная площадка будет в Иннополисе.

Innopolis Open 2021 по информатике имеет 2 уровень перечня РСОШ, что позволит победителям и призёрам олимпиады получить преимущество при поступлении в Университет Иннополис и другие вузы.

Регистрация

По всем вопросам: [email protected]

Hello Codeforces!

There is something new for you. It seems that now it will be easier to reuse problems from the archive for educational and other purposes.

As you know, problems from past Codeforces rounds can be added to mashups simply by their codes of the form like 1234D (contest ID + problem letter). I myself regularly used this when I taught at Saratov University — it was very convenient to prepare trainings: problems have expected complexity and topics, there are Russian and English statements, you can see the analysis and many solutions. Because of hacks and uphacks, problems in the archive usually have strong tests. Almost all of them are well-prepared. In addition, with the help of user lists, you can easily pick up problems for a group of students that they did not solve.

But there was also an issue: the problems in such trainings were easily googled. And if the majority of adult participants could cope with the temptation to spy on the solution or tests, then beginners sometimes acted dishonestly. I received several requests to come up with something with this flaw. One of the most recent such requests was from Daniel Darooha Sleator (https://en.wikipedia.org/wiki/Daniel_Sleator). Thanks, Danny!

So the work seems to be complete. Meet a new feature on Codeforces: now you can rewrite statements for problems in mashups, completely replacing it with your own. More details about the capabilities of the new functionality:

• a new icon-link appears in the problem list in mashups, by clicking on which there will be a form for creating/editing a new statement;
• you can use the original text of the statement as a template when writing your own: be very careful — you must exactly repeat all the details of a statement so that problems do not formally differ;
• this form compares the set of formulas in the original text and the new statement, and if they differ as sets, there will be a corresponding detailed warning;
• you can specify your own tests from a statement (examples) — here you also need to be very careful so that they are formally correct;
• if you added examples, then solutions will be judged on them first, and only after on official tests;
• you can upload your own image files and use them in statements;
• there is a setting to temporarily disable the use of the new statement (for example, if it is still under development).

Considering that there are already more than 6500 problems in the archive, an excellent perspective opens up for organizing trainings and educational sessions.

I hope this innovation will be useful. Write in the comments what can be improved and/or corrected.

M.

Hello Codeforces!

On Nov/19/2020 17:35 (Moscow time) Educational Codeforces Round 98 (Rated for Div. 2) will start.

Series of Educational Rounds continue being held as Harbour.Space University initiative! You can read the details about the cooperation between Harbour.Space University and Codeforces in the blog post.

This round will be rated for the participants with rating lower than 2100. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.

You will be given 6 or 7 problems and 2 hours to solve them.

The problems were invented and prepared by Roman Roms Glazov, Adilbek adedalic Dalabaev, Vladimir vovuh Petrov, Ivan BledDest Androsov, Maksim Neon Mescheryakov and me. Also huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Good luck to all the participants!

Congratulations to the winners:

Congratulations to the best hackers:

And finally people who were the first to solve each problem:

UPD: Editorial is out

Hello Codeforces,

I'm glad to invite you to our first contest Codeforces Round 684 (Div. 1) and Codeforces Round 684 (Div. 2) which will be held at 17.11.2020 17:35 (Московское время) . The problems are invented and prepared by AliShahali1382, Mehrdad_Sohrabi, and Mohammad.H915. The round is rated for both divisions. You will be given 5 problems and 2 hours 15 minutes to solve them. I recommend you to read all the problems :)

Firstly I'd like to thank isaf27 for coordinating and reviewing the round, as well as helping with many different things.

Thanks for our testers 300iq, coderz189, Atreus, Shayan.P, Retired_cherry, morzer, BledDest, UnstoppableChillMachine, MAMBA, prabowo, WNG for testing and giving very helpful advice.

Finally, thanks to MikeMirzayanov for very nice and convenient Codeforces and Polygon platforms.

I hope you all will find the problems interesting. I wish you high scores and good luck!

Scoring distribution:

Div. 1: (500-500)-1250-1750-2500-2500

Div. 2: 500-1000-(750-750)-2000-2500

UPD : Editorial is out.

Three Regionals Cup — 2020 on the tasks of Moscow Regionals 2020, Belarus and Baltic Regionals 2020, and Northwestern Russia Regionals 2020 is traditionally opened in this year at the Yandex.Contest platform in the format of three virtual contests. On the cup page, you may register for those contests.

You may use the plain Yandex logins or OpenCup or other pre-generated logins (choose the appropriate link at the top of the page).

The regionals results will be included in the cup standings. The result of the Cup is the sum of the Grand Prix 100 (similar to Opencup) scores for all three regionals at 0:00 Nov 30.

Hello, Codeforces!

On behalf of Meet IT, I'm glad to invite you to (Codeforces Round #683 by Meet IT (Div1, Div2) which will take place this Sunday (15th November).

The round lasts 2.5 hours and is rated for both divisions.

What is Meet IT?

We are a family of enthusiastic and motivated young people passionate about programming and mathematics. We build a community where people learn together, motivate and help each other.

Meet IT family members worked hard over the last few months to provide you with our favourite challenges we came up with. We hope that you will enjoy them as much as we did :)

We are enthusiasts of short and clear problem statements, strong pretests, and happy participants!

Every effort is valuable for us, and therefore I'd like to thank everyone who has contributed to the creation of this round:

• Co-founders of Meet IT: Mateusz and Paweł for guiding Meet IT projects and making things happen.
• Maciej, Piotr and Michał. Without their commitment in early years of Meet IT the Family would not exist.
• Round coordinator antontrygubO_o for endless discussions about the problemset.
• pawelek1 for coming up with problem ideas.
• tnowak for massive support in the work on harder tasks.
• staniewzki and jjaworska for developing the most challenging problem of the round.
• pasawicki for interest in tennis which was an inspiration to one of the problems, and for preparing another problem.
• lcaonmst for preparing a problem quickly and diligently.
• Mohamed.Sobhy for coming up with a nice easy problem and preparing it.
• Amtek for enduring my repetitive reminders to prepare a problem.
• flaviu2001 for his excitement about the round after testing and help to improve the shortcomings.
• _h_ for help in providing a high-quality editorial to one of the problems.
• dorijanlendvaj for firmly complaining about one edgy problem that pushed us towards substituting it with a better one.
• kobor for providing beautiful pictures for the removed problem. :(
• Devil for coming up with the substitution problem :), without you we would be still finalizing the problemset.
• arsijo for paying special attention to statements clarity during testing.
• zdolna_kaczka for winning the virtual contest among testers.
• Anadi for inventing an alternative solution to one of the hard problems as well as his kind comments and suggestions.
• Farhan132 for his ideas on how to improve the problemset in the second division.
• Linkus and a.piasta for showing the need to reduce the round difficulty a bit.
• The Army of Testers: ffao, RetiredPlayer, Retired_cherry, Whistleroosh, ijontichy, coderz189, AwesomeHunter, H4ckOm, TeaTime, hg333.
• MikeMirzayanov for the amazing platforms Codeforces and Polygon.
• all the people who strive for Meet IT Family to grow.
• Last but not least, my dear wife Marta who was very supportive throughout the long process of preparing the round.

UPD

I'm also thankful for Swistakk for testing the round thoroughly. Sorry for forgetting! I wrote the announcement sometime before that. I totally don't get why he got downvoted, please give him as much contribution as he deserves!

UPD 2

There will be $$$6$$$ problems in each division, with $$$4$$$ problems shared. One of those will have a subtask!

We strongly recommend to read all the problems. You have been warned :)

Scoring:

Div 2: 500 — 1000 — 1250 — 2000 — 2250 — (2500 + 750)

Div 1: 500 — 1000 — 1250 — (1750+750) — 3000 — 3000

UPD 3

We would like to host a stream shortly after the contest. We haven't yet figured out the details, you can expect some backstage stories about the round, Meet IT, and casual discussion. Stay tuned!

UPD 4

We've added the link to the stream which shows on the Streams pannel on the right. You're more than welcome to join our stream

UPD 5

Editorial is ready!

UPD 6

We hope you've all enjoyed the round despite some minor issues. Congratulations to the winners!

Division 1:

1. Um_nik (the only person to solve all problems!)

2. ecnerwala

3. Benq

4. ainta

5. ksun48

Division 2:

1. shb

2. jz_597

3. 1700012703

4. XueYJ

5. zybkl

Good Evening Codeforces! ^_^

This round is unrated; please read this to know why.

I invite you to participate in Codeforces Round #682 (Div.2) taking place on 13.11.2020 17:35 (Московское время). The round, authored by Anti-Light and me, is rated for users rated less than 2100, while other users can participate non-competitively.

The round features six problems, and you have 2 hours to solve them. There may, or may not, be an interactive problem; regardless, you should know how to deal with them.

I would, now, like to thank–

• antontrygubO_o for coordination.
• AwakeAnay and AsleepAdhyyan for helping me solve one of the problems.
• BRCode for making 3b1b-style video editorials of the problems!
• knightron00 for helping with preparation.
• Devil, Dragnoid99, far_from_NOOB, IaMaNanBord, Osama_Alkhodairy, prabowo, taran_1407, Tarrus, Tathagat_shah, TheOneYouWant, Utkarsh.25dec, Vivek1998299, _Aaryan_, aryanc403, dorijanlendvaj, coderz189, hugopm, kshitij_sodani, ltc.groverkss, nishkarsh, Roham, shash42, socho, talibmohd, thenymphsofdelphi, Monogon, Ari, 300iq, AmShZ, errorgorn, tejas10p, solvemproblr, neil__, aujasvit, TeaTime, stack_overflows, manik.jain, namanbansal013, Gur27, and DarkCraftPlayz for testing!
• MikeMirzayanov for Codeforces and Polygon platforms– Polygon is still remarkable!

We will announce the scoring distribution shortly. The scoring distribution is 500–750–1250–1750–2250-3000.

Good luck, and stay safe!

UPD: Editorial

For students in high school or below—

Participants who are currently in high school or below are eligible to win prizes — 25 USD gift cards to 5 random participants who solve at least 3 problems. Prizes are sponsored by Athena Education and are NOT related to Codeforces. To be eligible, please fill this form (it will be closed after the round ends). If you're interested in participating in other technical events, such as Machine Learning and Computational Linguistics, please head over to exunclan.com.

Hello, Codeforces!

First and foremost, we would like to say a massive thank you to everyone who entered and submitted their answers to the first, second, third, and fourth Kotlin Heroes competitions which were held previously: Episode 1, Episode 2, Episode 3 and Episode 4.

Ready to challenge yourself to do better? The Kotlin Heroes 5: ICPC Round competition will be hosted on the Codeforces platform on Nov/12/2020 17:35 (Moscow time). 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.

Everyone who takes part in this round will get an electronic Participation Certificate.

There is also a special recognition prize from the ICPC: ICPC- experience, an invitation to the Moscow World Finals 2021, all-inclusive on-site (hotel, meals, ceremonies, and swag, are included; visa, flights, transportation to the contest location is not).

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 9 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 5: ICPC Round (Practice), where you can try to solve a few simple problems in Kotlin. All the solutions are open, which means that you can look at the solution even if you haven't solved the problem yet. The practice round is available by the link.

We wish you luck and hope you enjoy Kotlin.

UPD: The editorial can be found here.