Всем привет!

На днях состоится Открытая олимпиады школьников по программированию. Олимпиаду подготовила Московская методическая комиссия, известная вам также по Московской олимпиаде школьников по программированию, Московской командной олимпиаде и олимпиаде Мегаполисов (раунды 327, 342, 345, 376, 401, 433, 441, 466, 469, 507, 516, 541, 545, 567, 583, 594, 622, 626, 657, 680, 704, 707, 727, 751, 775, 802, 829, 852).

Открытая олимпиада составляется из самых интересных и сложных задач, которые были предложены многочисленным коллективом наших авторов, поэтому мы решили провести нерейтинговое зеркало олимпиады на Codeforces. Олимпиада проходит в два тура, каждый из которых состоит из $$$4$$$-х задач, неупорядоченных по сложности, и $$$5$$$ часов на их решение. Сложность задач сопоставима с уровнем Div. 1. За каждую задачу можно получить до $$$100$$$ баллов, которые распределены по нескольким подзадачам с различными ограничениями, что позволяет участникам получить частичные баллы. Оценивание происходит по формату IOI, где участник получает полный отчёт по тестированию по всем тестам Online-подгрупп во время соревнования. Особенностью открытой олимпиады является то, что в некоторых задачах присутствуют Offline-подгруппы, результат по которым будет доступен только после конца соревнования. Обратите внимание, что во время соревнования вам не будет доступна таблица результатов.

Зеркало на Codeforces состоится в 08.03.2024 12:05 (Московское время) и 09.03.2024 12:05 (Московское время).

Задачи соревнования были придуманы и подготовлены Mangooste, vaaven, Tikhon228, ViktorSM, isaf27, TheEvilBird, sevlll777, Papaz239 и pakhomovee под руководством Ormlis, grphil и Андреевой Елены Владимировны.

Отдельное спасибо MikeMirzayanov за системы codeforces и polygon, который использовался при подготовке задач этой олимпиады.

Большое спасибо тестерам олимпиады: dshindov, FelixDzerzhinsky, Adikolon, isaf27, adepteXiao, talant, AgafonovArtem, Dart-Xeyter, inhabitant, Kapt, Siberian, alexashkins, alexxela12345, Sweezy, v0s7er, MOHOXPOM, Titoffifee.

Всем удачи!

UPD1: Решения были протестированы на offline-группах. Также доступна таблица результатов для первого дня.

UPD2: Решения были протестированы на offline-группах. Также доступна таблица результатов для второго дня.

UPD3: Общая таблица результатов

Привет, Codeforces! 😇

Мы рады пригласить вас поучавствовать в Codeforces Round 932 (Div. 2), который состоится во 05.03.2024 17:35 (Московское время) 🔥 😱 🤩

Раунд был полностью подготовлен учениками ШЦПМ 💓 (Школы Центра Педагогического Мастерства): IzhtskiyTimofey, AndreyPavlov и мной. Тематикой всех задач послужит наша любимая школа 😈

Этот раунд будет рейтинговым для участников, чей рейтинг ниже 2100 😊 Участники с более высоким рейтингом могут принять участие вне конкурса 😋

Мы хотели бы поблагодарить 💕:

• Нашего замечательного координатора Artyom123 за помощь в подготовке задач и ценные советы! 😍

• Учеников ШЦПМ azureglow и max0000561 за предложенные задачи 😎

• Нашего преподавателя ШЦПМ grphil за выращивание молодых талантов 💋

• TheEvilBird и NToneE за составление замечательных контестов для группы суперхард 🤮

• Geothermal за подробный фидбек по задачам и улучшение качества условий на английском языке 💘

• Наших тестеров A_G, SomethingNew, induk_v_tsiane, zwezdinv, k1sara, meowcneil, antonis.white, maomao90, MOHOXPOM, qualdoom, makrav, sergeev.PRO, Kihihihi, DimonKrutoi, htetgm, tiom4eg, Mikhango, MrEssiorx, adepteXiao, YakovLya, sunsh1ne, AVdovin, Egorsa, mishgun, dasha..zhilina, marzipan, kaido, jgjgjjg, mkshh, Makarchik_228, Nikitun за предложения по улучшению задач 😘

• MikeMirzayanov и всей команде Codeforces за создание прекрасных платформ Codeforces и Polygon 💖 💙 💚 💛

Вам будут предложены 6 задач и 2 часа на их решение! Мы постарались сделать для вас интересные, красивые, NP-полные задачи с сильными претестами 😁

Разбалловка: $$$500 - 1000 - 1500 - 1750 - 2500 - 3000$$$ ✨

Желаем всем удачи на раунде, а также мы бы хотели пожелать удачи участникам предстоящей Открытой олимпиады по программированию и РОИ! 🥇

UPD: Разбор

UPD2: Поздравляем победителей!

Div. 2:

1. Sakura_lenlen

2. keeping_practicing

3. INeedCarb

4. LJL_T

5. yyyz04

Div. 1:

1. tourist

2. jiangly

3. BurnedChicken

4. m_99

5. Sugar_fan

Мы извиняемся за дизбаланс нашего раунда, однако надеемся вам понравились наши задачи!

Hi,

We would like to invite you to participate in the live online mirror contest of The 2024 ICPC Asia Pacific Championship next weekend. ICPC Asia Pacific Championship is a new playoff round introduced to the Asia Pacific region this year. It is the contest for top non-winning teams from all regional contests in the region to qualify to the World Finals. See the region rules and competition page for more details.

The official contest is scheduled to start at Saturday, 2 March 2024, 9am (UTC+7). The live online mirror contest is scheduled to start only 5 minutes later, to keep both contests run almost in sync. The contest is 5 hours long and consists of several problems.

Please note that we might have to postpone the live online mirror contest in case the official contest is delayed. This is to the ensure that the tasks are not available to the public until the official contest starts. The official contest will be livestreamed here and the scoreboard can be accessed here.

The contest will use ICPC-style scoring (same as the official contest) and will be unrated. You can participate as an individual or as a team, although as a team of three members is preferred.

See you on top of the leaderboard.

The 2024 ICPC Asia Pacific Championship Judges

UPD1: The official contest is postponed by (at least) 30 minutes, so the mirror contest is postponed similarly.

UPD2: The official contest is postponed by 20 minutes (instead of the originally announced 30 minutes) after its original schedule, but the mirror contest is still scheduled to start 30 minutes after its original schedule to avoid more confusion.

UPD3: The analysis is available here

Hello, Codeforces!

I invite you to participate in Codeforces Round 931 (Div. 2), which will be held on Mar/01/2024 17:35 (Moscow time).

The round will be rated for participants with rating lower than 2100. Participants with higher rating can participate in round unofficially.

You will have 2 hours to solve 5 problems, with one of the problems having 2 versions. One or more interactive problems may occur in the round, so please read guide for interactive problems before the contest.

All problems are authored by me.

I would like to thank:

• Akulyat for round coordination and help with preparation

• A_G, okwedook, rui_er, jdurie, lunchbox, _rey, wjli, .-O_O-., aryanc403, akshaykhandelwal, PartTimeCoder, carnation13, its_pranjal_83, Ianlsam, Immerser, vikram108, praneeth6116, soham976roy, and Dev_30 for testing the round and providing useful feedback.

• MikeMirzayanov for Codeforces and Polygon platforms.

Good luck to all participants!

UPD: Score distribution: 500 — 1000 — 1500 — (1500 — 1250) — 3250

UPD2: Editorial

UPD3: Congratulations to the winners!

Div1 + Div2

Div2

"You are braver than you believe, stronger than you seem, and smarter than you think." — A.A. Milne

Hello Codeforces!

I have the pleasure of inviting you to participate in Codeforces Round 930 (Div. 1) and Codeforces Round 930 (Div. 2), which will start on Feb/29/2024 17:35 (Moscow time).

You will be given 6 problems and 2 hours to solve them in both divisions.

One of the problems may be interactive. So, please refer to the guide on interactive problems if you are unfamiliar with them.

The problems were prepared and authored by wuhudsm, chromate00, Psychotic_D and MagicalFlower.

We would like to thank :

• irkstepanov for coordinating the round;
• BurnedChicken for the only LGM testing;
• amenotiomoi,siganai, vgtcross, amethyst0, dognotlike, alireza_kaviani, and dorijanlendvaj for GM and IGM testing;
• aryanc403, k1r1t0, Little_Sheep_Yawn, Amir_Parsa, blxst, pavlekn, Error_Yuan, IceKnight1093, aufannn, Mingyu331, Akulyat, Arpa, and mhtkrag for M and IM testing;
• O--O, Abhishek_Srivastava, MrDelrus, htetgm, Silver_Fox, dhyang24, and milind0110 for CM testing;
• brave-kid, adventofcode, vikram108, mafailure, AnanasClassic, Yugandhar_Master, FD..LH..lloyJ, lemoncookie, and flakes24 for Expert testing;
• Banis, stepan.karpov, BF_OF_Priety, and ONEHUNDREDPUSHUPS for Specialist testing;
• HexShift for the only Pupil testing;
• JaberSH1 for the Newbie testing;
• tibinyte for the Illegal newbie lying face testing;
• MikeMirzayanov for the great Codeforces and Polygon platforms;
• And at last but not least, You for participating in the round!

Good luck, and may the code be with you!

UPD: Score distribution:

Div.1: $$$500 - 1000 - 1500 - 2000 - 2500 - 2750$$$

Div.2: $$$500 - 1000 - 1500 - 2000 - 2500 - 3250$$$

UPD2: Let's continue the streak of announcements with photos of the authors and coordinator.

UPD3: Editorial is out.

UPD4: Top Performers

Div.1

Div.2

“It is not important to be better than someone else, but to be better than you were yesterday.” — Master Oogway, Kung Fu Panda

Hello, Codeforces! We are proud to present Codeforces Round 929 (Div. 3), and we hereby invite all of you to take part in it. This round will start on Feb/27/2024 17:35 (Moscow time). You will have 2 hours and 15 minutes to solve 7 problems. The penalty for a wrong submission is equal to 10 minutes.

This round will be rated for participants with ratings lower than 1600. However, all of you who wish to take part and have a rating of 1600 or higher, are welcome to register for the round unofficially.

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.

Remember that only the trusted participants of the third division will be included in the official standings table. As stated in this blog, this is a compulsory measure for combating unsporting behaviour and upholding gracious professionalism. 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, then the round will be rated for you.

The problems were authored and prepared by erniepsycholone, snowysecret, dbsbs, jerryliuhkg, lomienyeet, and our beloved coordinator Vladosiya.

We would like to thank:

• Vladosiya for his high-speed coordination;

• arvindf232 for Legendary Grandmaster testing;

• step_by_step for International Grandmaster testing;

• physics0523, culver0412, AHappyPotato for Grandmaster testing;

• pavlekn for Master testing;

• moonpie24, anthony123, mariowong123 for Candidate Master testing;

• peshkoff, ksodp, SashaT9, Elison, MoLotfi for Expert testing;

• DBSHoShunNgai, Doncho_Bonboncho for Specialist testing;

• myvaluska, dbsMarco, dbsptl for Pupil testing;

• CannotPupil, KyleLeungHS for Newbie testing;

• MikeMirzayanov for creating Codeforces and Polygon.

We hope that this contest, regardless of your background, rating and result, will increase your exposure to competitive programming and make you better than you were yesterday. Have fun!

UPD: Let's continue the streak of announcements with photos of the authors. This time with our coordinator and testers :)

UPD2: We discovered the screencast from Um_nik a short while before the end of the contest, and it had around 400 views by the end of the contest. Round is still rated, however, people who have used his solutions will be punished.

UPD3: Editorial is out

Привет, Codeforces!

В Feb/23/2024 17:35 (Moscow time) состоится Educational Codeforces Round 162 (Rated for Div. 2).

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, Максим Neon Мещеряков и Роман Roms Глазов. Также большое спасибо Михаилу MikeMirzayanov Мирзаянову за системы Polygon и Codeforces.

Удачи в раунде! Успешных решений!

UPD: Разбор опубликован

mesanu, SlavicG and I are very excited to invite you to Codeforces Round 928 (Div. 4)! It starts on Feb/19/2024 17:35 (Moscow time). We would also like to give a very special thanks to the efforts of MikeMirzayanov and Vladosiya, who helped significantly with the preparation of the round!

The format of the event will be identical to Div. 3 rounds:

• 5-8 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 (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).

We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.

Only trusted participants of the fourth 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 fourth 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 1400 or higher in the rating.

Regardless of whether you are a trusted participant of the fourth division or not, if your rating is less than 1400 (or you are a newcomer/unrated), then the round will be rated for you.

Thanks a lot to the testers: MADE_IN_HEAVEN, Gheal, Dominater069, Phantom_Performer, Vladosiya, htetgm, hbarp, tvladm!

We suggest reading all of the problems and hope you will find them interesting. Good luck!

UPD: Editorial is posted!

Привет! В 18.02.2024 15:05 (Московское время) начнётся Codeforces Round 927 (Div. 3) — очередной Codeforces раунд для третьего дивизиона.

В раунде используются задачи JetBrains Academy Youth Challenge. Если вы участвовали в нем, не участвуйте в этом раунде.

Задачи подготовлены denk, step_by_step, goncharovmike, ikrpprppp, pashka, Vladosiya и MikeMirzayanov.

Большое спасибо awoo, BledDest, buyolitsez, EgorUlin, Gojova, GrandFruit, Hello_zoka, petyb, scanhex, senjougaharin, shnirelman, SomethingNew, Toy_mouse, Zandler за тестирование раунда.

Как обычно для раундов третьего дивизиона:

• в раунде будет 6-8 задач
• длительность раунда 2 часа 15 минут
• раунд проходит по правилам ICPC, штраф за неверную попытку 10 минут
• раунд рейтинговый для участников с рейтингами до 1600
• после раунда будет 12-часовая фаза открытых взломов

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 пяти 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 удачи!

UPD: Разбор

Hello, Codeforces!

Welcome to the think-cell Round 1 supported by think-cell, which will start on Feb/17/2024 17:35 (Moscow time). It will be a combined rated round for both divisions. All problems were authored and prepared by Elegia and satyam343.

We would like to thank:

• errorgorn for round coordination and help with preparation
• KAN for helping with the preparation of problems
• Alexdat2000 for Russian translation
• GoatTamer and Non-origination for discussing problems with us while our proposal was in review and testing the round.
• Kaitokid, antekb, vgtcross, riano_, mtw, AboAbdoMC, Vladithur, BERNARD, milind0110, conqueror_of_tourist, Um_nik, gamegame, htetgm, brobat, LucaLucaM, the_hyp0cr1t3, tibinyte, 18o3, ExpensiveAC, MateiKing80, udhavvarma03, Non-origination, RDDCCD, Kuroni, Brovko, LipArcanjo, andrei_boaca, nok0, oursaco, ffao, prvocislo, SmolBrain, dario2994, brunovsky, tabr, PurpleCrayon, IceKnight1093, aryanc403 and Golovanov399 for testing the round
• MikeMirzayanov for great systems Codeforces and Polygon.

You will be given $$$9$$$ problems and $$$3$$$ hours to solve them. One of the problems will be divided into two subtasks. One of the problems will be interactive. Make sure to read this blog and familiarize yourself with these types of problems before the round!

We hope you'll like the problemset!

UPD 1 : The score distribution is $$$500 - 1000 - 1500 - (1250 + 1000) - 2500 - 2750 - 3500 - 3500 - 5000$$$.

Congratulations to the winners!

1. cnnfls_csy

2. Geothermal

3. Benq

4. gyh20

5. Ormlis

6. jiangly

7. tourist

8. ksun48

9. Petr

10. maroonrk

Congratulations to the first solves as well!

• A : SSerxhs

• B : SSerxhs

• C : M_A

• D1 : hitonanode

• D2 : hitonanode

• E : ksun48

• F : MAOooOAM

• G : gyh20

• H : maroonrk

• I : Kapt [upsolved]

UPD 2: Editorial is out.

And now a word from our round partner – think-cell:

think-cell is the leading data visualization software for business presentations. Our mission is to offer the most intuitive user interface for generating complex data-driven charts and slides, while at the same time ensuring seamless integration with Microsoft Office. We work on challenging visualization problems, reverse-engineer Microsoft’s code, and reinvent how slides are created. think-cell is the only German company funding the C++ ISO committee delegation, so there is a good chance that components we invent will find their way into the standard.

Right now, we are looking for smart, creative C++ engineers with a solid theoretical background to join our engineering team.

Highlights of the role:

• We use the latest C++ features as soon as the compilers support them.
• We’re not afraid of advanced template metaprogramming or macros when they avoid code duplication or lead to cleaner, more readable code.
• We prefer algorithms and ranges (esp. ours!) over raw loops.
• We take the time to deliver perfect code.
• We love refactoring and modernizing old code and introducing our own libraries.
• If we can do better than the standard library, we write our own!
• If we have done something cool, we talk about it at C++ conferences.
• If we are missing a C++ language feature, we write a proposal and present it to the C++ standard committee.

Here is what we offer:

• A competitive salary from the start and a raise to EUR 130,000 annually after only one year.
• Full support with relocation to Berlin or the option to work fully remotely.
• An apartment for the first month if relocating to Berlin.
• Lifestyle-friendly working hours, no deadlines, no overtime.
• No scheduled meetings.
• An international team of brilliant minds.
• A flat organisation with respectful colleagues and plenty of room for your ideas.
• A working environment that is driven by the strive for excellence.

Already convinced?

P.S. don't forget to check out our developer blog to learn more about our commitment to the tech world!

Join think-cell Round 1 that will start on Feb/17/2024 17:35 (Moscow time) for a chance to challenge your skills among other developers and win the following prizes.

- First place: Apple iPad Air (10.9-inch iPad Air Wi-Fi 256GB),
- Second and Third place: Apple Watch (Apple Watch Series 9 GPS + Cellular, 41mm Aluminum Case with Solo Loop),
- 4-50 places: think-cell branded socks
- 200 additional socks will be distributed randomly among the rest of the participants who solved at least one problem and for whom this is not the first rated round!