MikeMirzayanov's blog

By MikeMirzayanov, 3 weeks ago, In English,

Hello, Codeforces!

I am pleased to announce the 2nd Hello Barcelona Programming Bootcamp in collaboration with Moscow Workshops ACM ICPC, which will be hosted by our partner Harbour.Space University together with Moscow Workshops ACM ICPC, ITMO University, Moscow Physics and Technology University, Saint Petersburg State University and Codeforces!



The boot camp will be held from September 27th to October 5th in Barcelona. This time it will be at the beautiful and technologically mind-bending Media-TIC building — the Smart Building of Tomorrow.



Media-TIC building — the Smart Building of Tomorrow

The world's greatest coaches will be attending: Andrew andrewzta Stankevich, Michael Endagorion Tikhomirov, Gleb GlebsHP Evstropov, Artem VArtem Vasilyev and other world renowned Russian coaches. As a coach, I will come too. The Chief Judge of the camp is Oleg snarknews Khristenko. Seriously, it will be a unique opportunity for teams around the world to learn from such well-known and successful coaches in the ACM-ICPC world.

Having visited the first Hello Barcelona programming Bootcamp in February, I left the event feeling inspired from the overall atmosphere. I am sure that all teams received an immense amount of knowledge and skills. As one of the coaches, all of the flattering reviews about the camp from the participants were pleasant for me to hear. I am very glad that these camps are becoming regular. Harbour.Space University and Moscow Workshops ACM ICPC have done a job worthy of admiration!

The Bootcamp will be split in two divisions:

  • Division A. Designed to prepare students to excel and win medals in the next ACM-ICPC World Finals.

  • Division B. Designed to help teams prepare for the next season of ACM-ICPC Regionals and international competitions. This is an appropriate introduction for teams and students new to the world of ACM ICPC and competitive programming competitions in general. The Division B curriculum features thematic lectures and contests.

The participation fee is unchanged: €1270 per person (cultural program, accommodation and half-board meals included).

Single participants and teams must register by July 1st, 2017 to receive the 15% off-Early Bird Discount, or the 20% off-Loyalty Discount, which is awarded to teams that participated in previous Moscow Workshops ACM ICPC boot camps.


Learn more about Barcelona ACM-ICPC Bootcamp

You can ask any questions by email: hello@harbour.space

Hope to meet you on the Bootcamp, Mike Mirzayanov

In order to experience the atmosphere of the event, I suggest you familiarize yourself with the photos and videos from the 1st Hello Barcelona programming Bootcamp in collaboration with Moscow Workshops ACM ICPC.

Read more »

 
 
 
 
  • Vote: I like it  
  • +137
  • Vote: I do not like it  

By MikeMirzayanov, 4 weeks ago, In Russian,

Общая информация

Саратовский государственный университет в первой половине августа проводит международную летнюю студенческую школу по программированию. Продолжительность школы — десять дней, школа пройдет с 31-го июля по 10-е августа 2017 года.

К участию приглашаются как команды из двух-трех человек, так и индивидуальные участники.

Школа пройдет в живописном месте, на одной из саратовских баз отдыха на берегу Волги. Участники будут расселены в уютных номерах по 2-4 человека и обеспечены трехразовым питанием. На территории базы имеется собственный пляж и спортивные площадки.

В программе школы запланировано 10 рабочих дней, включающих ежедневные пятичасовые тренировки, разборы задач, дорешивания. Будет прочитана серия лекций. Учебная программа рассчитана на студентов, которые хотят достичь значительных успехов на соревнованиях по программированию.

Read more »

 
 
 
 
  • Vote: I like it  
  • +82
  • Vote: I do not like it  

By MikeMirzayanov, 5 weeks ago, translation, In English,

ACM-ICPC World Finals 2017 will begin on May 24, 2017 at 15:00 (UTC). This event is the main event of the year in the world of sports programming!

This year ICPC Regional participation included 46,381 of the finest students and faculty in computing disciplines from 2,948 universities in 103 countries on six continents. A record 50,145 students and 5,073 coaches competed in ICPC and ICPC-assisted competitions this year, setting new records in participation.

Codeforces wishes the teams to show a vivid and interesting contest contest. We wish to find beautiful solutions, write without bugs and enjoy many accepted problems!

Links:

ACM ICPC World Finals 2017 English Broadcast:
ACM ICPC World Finals 2017 Indian Broadcast:
ACM ICPC World Finals 2017 Chinese Broadcast:
ACM ICPC World Finals 2017 Arabic Broadcast:
Broadcast from legends: Petr, tourist, Endagorion:

Read more »

 
 
 
 
  • Vote: I like it  
  • +292
  • Vote: I do not like it  

By MikeMirzayanov, 5 weeks ago, translation, In English,

Hello, Codeforces!

The ACM-ICPC World Finals 2017 event is running now. Tomorrow will be the main contest. During these days the directorate of ACM-ICPC shared some news.

  • Let me remind you that this season (2016-2017) is last, when the general sponsor of the championship is IBM. For 20 years, IBM has supported ACM-ICPC, investing millions of dollars annually. Thank you, IBM! At the moment, the model is actively being worked out, when there will be not one general sponsor, but there will be a fund in which several companies will participate. At the opening ceremony the Sport Programming Foundation was mentioned. I believe this Foundation will be the main one for the future seasons of the championship. However, these are not yet close plans.

    It was announced that the next three years the general sponsor of ACM-ICPC will be JetBrains! This is amazing news. Particularly pleased that this is actually a Russian company, and its executive director Maxim Shafirov coached the team of St. Petersburg State University, which became the world champion in 2000! I'm sure that the wonderful development environment from JetBrains in the future finals of the championship will await us as a pleasant bonus.

  • There is a reform of the qualifying stages of the championship. For example, now Rissian+ regional contest (NEERC) is not part of the European Regionals, but is a separate league of the Northern Eurasia. In general, eight leagues (read, super-regions) were singled out: Europe, Northern Eurasia, North America, Latin and South America, two leagues in Asia, Africa and probably Australia and Oceania. It is planned that each league will have its own separate finals with medals and the top 12 teams from each league will receive a ticket to the World Finals. While these are still distant plans, but the first steps have already been taken. Discusses its quota on the number of participations in the league finals (3 times).

  • Unfortunately, this year a significant part of the teams did not receive a visa at all (5 teams) and a dozen more could not arrive completely because of the visa problems of one of the participants. Saratov State University, apparently, is among them. It was announced the decision to invite to the next Wold Finals without any selections and quota accounting for 5 teams that could not come this year. In addition, it is proposed to give a +1 year to participate (without taking into account any other requirements) to all teams that could not arrive completely.

  • The next Finals will be held in Beijing, and a year later — in Kochi (India).

Such news.

Read more »

 
 
 
 
  • Vote: I like it  
  • +523
  • Vote: I do not like it  

By MikeMirzayanov, 5 weeks ago, In English,

Hello!

I'm happy to visit Rapid City and meet so many bright contestants here!

I have Codeforces laptop stickers with me and I'll be glad to give them as small gifts to participants of the World Finals. You can find me (I do not have many stickers, be quick) to get gifts. My friend collects coins, so I'll be glad to receive a coin from your country as a souvenir.

See you. And good luck on the contest!

Mike

UPD Still have few stickers. You have a chance!

Read more »

 
 
 
 
  • Vote: I like it  
  • +170
  • Vote: I do not like it  

By MikeMirzayanov, 7 weeks ago, translation, In English,

Hello, Codeforces!

I'd like to invite you to join in Playrix Codescapes Cup for the both divisions that will be held on May 11 at 18:35 MSK. The round is rated and open for everyone.

Problems are prepared by KAN, Al.Cash, MikeMirzayanov and fcspartakm. Huge thanks to Playrix company for making this round possible. Hope you enjoy the round!

Playrix is one of the leading mobile games development companies in the world. Its distributed team consists of 450 professionals from around the world. The company has released three successful mobile free-to-play games – Township, Fishdom and Gardenscapes. All of the projects have consistently been among the Top 50 Grossing Apps for iOS and Google Play since their release.In 2016, Facebook named Gardenscapes game of the year.

Company is looking for Russian-speaking C++ developers.

Prizes from the Playrix company:

  • Top 1: iPadPro 9,7 + PowerBank + T-shirt with logo
  • Top 2-5: PowerBank + T-shirt with logo
  • Top 6-50: T-shirt with logo
  • (New!) Random 5 participants (not from top-50, submitted at least once): T-shirt with logo

Congratulations to the winners!

  1. tourist
  2. LHiC
  3. subscriber
  4. W4yneb0t
  5. enot110

The problem analysis is published.

Read more »

 
 
 
 
  • Vote: I like it  
  • +464
  • Vote: I do not like it  

By MikeMirzayanov, 2 months ago, translation, In English,

Hello!

Are you missing something new? I have something to please you.

Regularly I host some events — Olympiads, onsites, and eventually, examinations and tests for students. On the one hand, Codeforces already offers a unique functionality — groups, the integration with Polygon, the possibility of choosing tasks from the archive and so on. But it doesn’t enough!

Domains for groups

Here is an example of such group. It is open for all — join it and look: http://example.contest.codeforces.com

Domain

Now when you are editing a group, you can specify its subdomain (from 3 to 20 alphanumeric characters, starts with a letter). When you specify the domain, the group will be accessible by a link http://yourgroupdomain.contest.codeforces.com. According to this link, the following is correct:

  • Nothing extra will be displayed — the site contains only the information about competitions and blogs of your group and nothing else.
  • All you need to display — is an HTTP access to 212.193.33.6. If you host the official contest, important coaching or examination — block all the rest of the Internet, except for this IP-address.
  • Today such groups can only contain private competitions and trainings. For example, you can make your mashup and set it up as you need. Maybe, later we will make something with this restriction, but for now — it is like this.
Permitted subnets for the domain

To be sure that extra people will not click on your link http://yourgroupdomain.contest.codeforces.com, you can block the access to it by IP. Specify the exact IP or subnet address. For example, 188.93.56.35;212.193.32.0/19.

The language of the interface of the domain

Probably, when you host the event, only the English (or only Russian) interface is enough for the participant. Use this setting to select the desired behavior.

Header html

You can change the site header at http://yourgroupdomain.contest.codeforces.com, so that there will be not the familiar logo of Codeforces, but the logo or name of your event. For example, when I host the inter-university Olympiad in Saratov, I set it to <h3>Interuniversity Olympiad on programming 2017 (Saratov)</h3>.

Users of the domain (sidebar)

It is very likely that if you hold an Olympiad or something similar, participants may not have the Codeforces account, the information about participants comes from a separate registration, and you want to see usual names in the interface, such as ‘John Doe, Berliandsky SU, 3 Course’, rather than the participant’s handle.

You can add synthetic users to your group with a domain (using these accounts, you can only log the group through the domain). Use the special function “Users of the domain”. Each line corresponds to one user and must be written in the format: contest ids (separated by commas) | Handle | Password | Name. Here's an example of this setting for the domain example.contest.codeforces.com:

213380 | u01 | 371111 | Petr Korotkevich
213380 | u02 | 627492 | Gennady Soejima
213380 | u03 | 491591 | Makoto Knuth
213380 | u04 | 581711 | Donald Cormen
213380 | u05 | 057259 | Thomas Mitrichev

Yes, you can feel like Peter Korotkevich, log on http://example.contest.codeforces.com, and use the login u01 and the password 371111.

Privacy settings

You have a possibility to set all as you wish. For example, to maximally block the access to the group (only by the domain, do not allow extra users), make the closed’ group, and the policy of registering of its membersonly by invitation`. In this case, only domain users (see the point above) and users invited to the group will be able to access the domain address.

For private contests you can set additional settings:

  • Allow practice — whether it is possible to solve problems after the official termination in an informal mode of upsolving.
  • Allow virtual participation — whether it is possible to participate virtually after the official termination (or whenever you want, if there is no start time).
  • Allow out of competition participation — it is reserved for out of competition participation, while only the users of the domain can be registered as out of competition (for the right users, add the symbol 'o' after the contest id, for example “213380o | u01 | 371111 | Petr Korotkevich”).
  • Allow self-registration — whether it is possible for participant to make a self-registration (if no — register him).
  • Allow unregistered users to observe the competition — whether it is possible for the participant of the group who is not registered to a contest enter the contest and see the problems, status, standings and other details.
  • Turn on common status — whether it is possible for participants to see the information about other participants’ submissions, or the information about their own attempts is the only available.
  • The duration of freezing and unfreeze time. Be careful during transfer of the contest — unfreeze time must be changed independently.
  • The policy for showing tests. Here are possible options: "do not show at all", "show failed tests of own solutions", "show all tests completely".
  • The policy of showing other people's attempts. Here are possible options: "do not show at all", "show to participants who solved the problem," "show to everyone."

Read more »

 
 
 
 
  • Vote: I like it  
  • +609
  • Vote: I do not like it  

By MikeMirzayanov, history, 2 months ago, translation, In English,

April 26, 15:35 (UTC) the second Wild Card Round of VK Cup 2017 will take place.

Participants are invited to achieve progress in solving an unusual problem. VK Cup teams which were advanced to the Round 2 (and didn't advance to the Round 3) will take part in VK Cup 2017 - Wild Card Round 2 officially. In addition, this round will be open to the public for unofficial participation for everybody. Registration will be open for the whole round duration.

The round will be one week long. After the end latest submission (with positive score) of each participant will be judged on system tests.

Good luck!

Read more »

 
 
 
 
  • Vote: I like it  
  • +117
  • Vote: I do not like it  

By MikeMirzayanov, 3 months ago, translation, In English,

Hello Codeforces!

I am pleased to announce a long term partnership with Harbour.Space University and Codeforces.

Harbour.Space is supporting the return of a new series of educational rounds on Codeforces!

They will take place with the regularity of ~2 times per month with the first round on 14:35 UTC, 27th of March, 2017.

Education Rounds Rules:

  • Scholarships to study Data Science, Computer Science and Cybersecurity in Barcelona for best performing participants, courtesy of Harbour.Space University (more details later!);
  • Classic Duration: 1.5 — 2.5 hours;
  • The goal is rather to practice and to educate, than to compete;
  • Not only problems, but also exercises can be used;
  • Useful, even well-known ideas can be reused in order to introduce them to a wide range of participants;
  • Unrated (perhaps only for now);
  • We will conduct them in the ACM-ICPC mode;
  • The results that are obtained after the end of the round, are preliminary;
  • After the end of the round will be a 24-hour period of open hacks — any visitor of Codeforces may try to hack any complete solution to a problem of the last round (either from a contest, or from practice), the source code of hacking solution is available (you can copy the text and, for example, stress it);
  • All successful hacks from the previous item will be added to the official test set and after as long as 24 hours after the end of the round retesting of all complete solutions will be made;
  • Only after the final standings based on improved test data, the results are final;
  • Our ability to process such problems are limited, so actually the test suites from the jury are expected to end up incomplete — we are looking forward to your hacks!

In February I had a new and wonderful experience of coaching top teams at the Barcelona ACM-ICPC Bootcamp hosted by Harbour.Space University. I was really impressed by the university, participating teams and fellow coaches from our community such as Endagorion, GlebsHP, Michael, Jacob and snarknews that were also there.

During the bootcamp it became clear to me that Harbour.Space University is a new type of university that’s reinventing the university experience. It is a modern, adaptable and flexible university that is doing amazing things in preparing talented students for careers in Computer Science, Data Science and Cyber Security.

All of their programs are developed in collaboration with the industry and are taught by the top professionals in the respective fields such as Viktor Kantor, Edith Elkind, Alexander Kulikov, Alex Dainiak, Sergey Nikolenko, Deepa Gupta and many others. I am delighted to be joining Harbour.Space fantastic faculty. Together we are developing a series of courses on competitive programming in addition to the bi-annual ACM ICPC Bootcamp that will be hosted by the university in Barcelona.

Read more »

 
 
 
 
  • Vote: I like it  
  • +217
  • Vote: I do not like it  

By MikeMirzayanov, history, 4 months ago, In Russian,

11 марта в 15:00 начнётся второй квалификационный раунд чемпионата VK Cup 2017!

Правила этого раунда будут совпадать с правилами Квалификации 1. К участию приглашаются команды, не участвовавшие в первой квалификации или набравшие в ней менее 2950 баллов. Те, кто успешно справился с первой квалификацией, могут принять участие вне конкурса, при этом их результаты никак не будут влиять на проход остальных команд. Разумеется, от команд, участвующих вне конкурса, также требуется соблюдение всех правил Чемпионата.

Раунд продлится 24 часа, такая продолжительность выбрана для того, чтобы все нашли себе удобное время для участия. Квалификационный раунд, как и все предстоящие раунды, требует отдельной регистрации, она будет открыта на протяжении всего раунда.

При регистрации на раунд состав вашей команды фиксируется и не подлежит дальнейшей модификации. Вы не сможете в будущем добавить или удалить члена команды. Пожалуйста, перед регистрацией убедитесь, что у вас нет желания изменить состав. Состав команды не сможет быть изменен, даже если вы отмените регистрацию на квалификационный раунд.

В Раунд 1 пройдут все команды, которые наберут положительное количество баллов, не меньше количества баллов у команды на 500-м месте.

Во время квалификации задачи тестируются системой только на претестах, а системное тестирование состоится после окончания раунда. Обратите внимание, что претесты не покрывают все возможные случаи входных данных, поэтому тщательно тестируйте свои программы! Взломов, падения стоимости задач во время квалификации не будет. Время сдачи задач не будет учитываться, однако будут учитываться штрафные попытки.

Категорически запрещается публиковать где-либо условия задач/решения/какие-либо мысли и соображения о них до окончания раунда. Запрещено обсуждать задачи с кем-либо, кроме вашего сокомандника. Будьте честны, пусть в Раунд 1 пройдут сильнейшие!

После окончания раунд станет доступен всем для дорешивания, а его задачи попадут в архив, в том числе и на английском языке.

Read more »

 
 
 
 
  • Vote: I like it  
  • +61
  • Vote: I do not like it  

By MikeMirzayanov, 4 months ago, In Russian,

Всем привет!

4 марта в 15:00 начнется первый квалификационный раунд чемпионата VK Cup 2017!

Раунд продлится 24 часа, такая продолжительность выбрана для того, чтобы все нашли себе удобное время для участия. Квалификационный раунд, как и все предстоящие раунды, требует отдельной регистрации. Регистрация уже открыта и будет открыта на протяжении всего раунда.

При регистрации на любой из квалификационных раундов состав вашей команды фиксируется и не подлежит дальнейшей модификации. Вы не сможете в будущем добавить или удалить члена команды. Пожалуйста, перед регистрацией убедитесь, что у вас нет желания изменить состав. Состав команды не сможет быть изменен, даже если вы отмените регистрацию на квалификационный раунд.

Если вы пока не уверены в текущем составе команды, то не регистрируйтесь на предстоящий раунд. Если вы не будете участвовать в первой квалификации или не пройдете по ее результатам в Раунд 1, то вы сможете попробовать свои силы во второй квалификации.

Чтобы пройти в Раунд 1, вам надо принять участие хотя бы в одной из квалификаций. Из каждой квалификации в Раунд 1 проходят все команды с положительным числом баллов, которые набрали не меньше баллов, чем команда на 500-м месте.

Во время квалификации задачи тестируются системой только на претестах, а системное тестирование состоится после окончания раунда. Обратите внимание, что претесты не покрывают все возможные случаи входных данных, поэтому тщательно тестируйте свои программы! Взломов, падения стоимости задач во время квалификации не будет. Время сдачи задач не будет учитываться, однако будут учитываться штрафные попытки.

Категорически запрещается публиковать где-либо условия задач/решения/какие-либо мысли и соображения о них до окончания раунда. Запрещено обсуждать задачи с кем-либо кроме вашего сокомандника. Будьте честны, пусть в Раунд 1 пройдут сильнейшие!

Результаты раунда не будут влиять на рейтинг, внеконкурсное участие в раунде не разрешается. Однако, после окончания раунд станет доступен всем для дорешивания, а его задачи попадут в архив в том числе и на английском языке.

Read more »

 
 
 
 
  • Vote: I like it  
  • +51
  • Vote: I do not like it  

By MikeMirzayanov, 4 months ago, In Russian,

Привет, Codeforces!

Мы с радостью сообщаем вам, что компания ВКонтакте совместно с площадкой Codeforces вновь проводит чемпионат VK Cup. К участию в VK Cup 2017 допускаются команды до двух человек, так как практика парного программирования широко распространена во всем мире, в том числе и ВКонтакте. За призы и звание победителя приглашается побороться русскоязычным молодым специалистам, студентам, школьникам и просто любителям алгоритмов и программирования.

Лучшие 20 команд по результатам отборочных интернет-этапов будут приглашены в финал соревнования, который состоится в июле 2017-го года в прекрасном городе Санкт-Петербурге. Компания ВКонтакте покроет расходы на проезд и проживание финалистов, которые будут бороться не только за звание лучших из лучших, но и призовой фонд чемпионата. Как и в прошлом году призы соревнования связаны с круглыми числами в двоичной системе счисления:

  • 1 место — 1048576 рублей
  • 2 местo — 524288 рублей
  • 3 местo — 262144 рубля
  • 4-8 места — 131072 рубля

Read more »

 
 
 
 
  • Vote: I like it  
  • +210
  • Vote: I do not like it  

By MikeMirzayanov, history, 5 months ago, In Russian,

Добрый день.

Прямо сейчас по всей России проходит первый тур регионального этапа. Очень надеюсь, что участники смогли собраться, не сажают досадные баги, а результаты их порадуют!

Предлагаю обсудить здесь задачи и решения, а так же наверняка в комментариях появится ссылка на опрос по результатам. Обязательно добавляйтесь, это интересно!

Как я понимаю, большинство регионов сегодня использует Яндекс.Контест. Надеюсь, чуть позже появятся и ссылки на официальные результаты.

Участники, болеем за вас!

UPD 1: Спасибо, The.Fusy. Опубликована суммарная таблица результатов по многим регионам. Пока в ней только первый тур, но скоро появится и второй.

UPD 2: Второй тур завершен. Теперь можно отдыхать и немного переживать за квоты на заключительный этап.

Read more »

 
 
 
 
  • Vote: I like it  
  • +134
  • Vote: I do not like it  

By MikeMirzayanov, history, 6 months ago, In English,

Hello Codeforces!

I'm pleased to announce the first championship hosted on the Codeforces platform. Welcome 8VC Venture Cup 2017!

8VC will be hosting a coding championship on Codeforces. The championship will begin on January 15 and take place in 2 rounds.

The contest will occur in two rounds:

  • The Elimination Round is online and takes place on January 15, 17:05 (UTC). Elimination Round follows regular Codeforces rules and consists of 7-8 problems. For this round, the complexity of the problems will be comparable to a regular Codeforces round. There are no eligibility restrictions to participate in the round.
  • The Final Round takes place on January 22, consists of 5-6 problems, and uses regular Codeforces rules. The complexity of the problems is higher than a regular Codeforces round. We will invite the top local finishers in Elimination Round to Woodside, CA to compete in the Final Round. In addition, we will invite the top 200 overall finishers to compete online.

Cool prizes are offered to winners and best participants.

PRIZES
  • Overall 1st place — $2000
  • Overall 2nd place — $1000
  • Overall 3rd-5th places — $500 each
  • Overall 1-50th place — t-shirts with 8VC and company logos
  • Local Winner — Dinner with Joe Lonsdale (founder of Palantir, Addepar and 8VC) and other Silicon Valley technologists
  • Local top finishers — Opportunity to meet with leadership from 8VC portfolio companies
ABOUT 8VC

8VC, which consists of Joe Lonsdale (co-founder of Palantir) and his core team from Formation | 8, is a Silicon Valley venture capital firm that invests in industry-transforming technology companies. The team's investment portfolio includes companies such as the selected companies below, and a host of other top technology platforms that leverage modern algorithms and data science to power their core business processes.


Connect to 8VC

Read more »

 
 
 
 
  • Vote: I like it  
  • +164
  • Vote: I do not like it  

By MikeMirzayanov, history, 6 months ago, translation, In English,

Hello, Codeforces!

At the request of Zlobober and other users I has implemented notifications on mentions. See the bell on the top of the page?

So far there is only the basic functionality and it is incomplete. But let's start with it for now.

Now notifications appear on mentions in comments only. For now it is impossible to disable it. We do not send anything on your email.

Let's test it together and understand how to move forward with this functionality.

From planned, proposed, discussed:

  • Notifications on сhanges in the comments, on blog posts and their edits (if mentioned once, do not send more on edits)
  • When you scroll, show a bell on the right side of the page, visually similar to the arrow ``scroll up'' on the left
  • Possible we will restrict functionality to avoid abuse from inadequate users
  • Special setting the profile
  • Move other notifications to the new system (notifications on talks?)
  • Shows a typical informational box in the right bottom on new notification

What else will be thinking?

Read more »

 
 
 
 
  • Vote: I like it  
  • +208
  • Vote: I do not like it  

By MikeMirzayanov, 6 months ago, translation, In English,

Hello, Codeforces!

New year brings changes to the Codeforces team. As you probably know GlebsHP completed his work as the chief coordinator of Codeforces. Gleb, thanks a lot! You did an excellent job and coordinated a lot of interesting rounds. You're a professional, an interesting person, you have impeccable taste to problems, and you proved to be brilliant and talented writer. Thank you that you were with us! Hope to see your tasks on Codeforces many times again!

Nikolay KAN Kalinin came to Gleb's place. He is also an experienced participant, Nikolay has already held several rounds as a coordinator. KAN seriously engaged in programming contests since he was 12 years old. His major achievements: he won twice All-Russian School Team Olympiad; he won All-Russian School Olympiad (the 1st place!); he has two Gold medals in International Olympiad in Informatics (IOI 2013, 2014), bronze medal in the ACM-ICPC World Finals 2016 and he took the third place at the RCC 2016. This is the highest level! I am very pleased that Nikolay has joined the Codeforces team. I am confident we will succeed!

And here there is the first innovation of 2017 year. The idea to ​​organize work with proposals has swirled in my head for a long time. It turned out well: KAN visited Saratov to get acquainted with the whole Codeforces team and celebrate the New Year together. And we not only had a good time, but found some time to discuss details how we see our work with writers. Here's what happened.

Writers Requirements

All the functionality described below is only available for experienced contestants and writers of past rounds. There are requirements on the number of rated contests depending on your color (magic does not work here, sorry).

color the minimum number of rating contests
blue 25
violet 15
orange 5
red no restrictions
Was already a writer in the past no restrictions

Please do not assume that the requirements are too strict. Our experience shows that it is hard to work with writers who are inexperienced as contestants . If you are a writer/jury member with experience in other competitions/events, please write KAN a private message about your wish to prepare a contest and describe your experience in this area. Be respectful to the coordinator decision, if it prompts you to achieve the general formal requirements prior to review your proposal.

Writers Reward

Preparation of the round is fascinating, but large and demanding work. We have the opportunity to reimburse the effort of the writers according to the following tariff:

Round Type $
Div 1 + Div 2 $250 + $50*
Div 2 $100 + $50*

An asterisk denotes a bonus, which is issued in case of work in time, without any issues

If a round is a part of a championship, there is an additional bonus, which is discussed separately.

I dream to raise reward to writers. I dream to see the most experienced, the most creative and interesting writers give our users the opportunity to participate in their rounds on Codeforces! Codeforces rounds attract record number of participants from around the world (the next frontier is 10000 registrations!), I personally offered a large number of problems — the chance to give an interest to participants is priceless.

Please send us your problems, spend contest proposals! We can make a platform, we can build a process, we can host championships. But we can't invent and prepare problems on each round.

How to propose a contest (можно читать всё!)

Those who meet the requirements will find the special link “propose a contest/problems” in the personal menu in the right sidebar. Click on it and you will have the opportunity to offer a contest, add problems to it. Read all instructions carefully. Carefully prepare and submit your proposal for a contest and for problems. I think that user interface is simple and intuitive.

Now, you can use only new system to submit proposals. If you have already received an answer from KAN for current proposal, you shouldn't transfer it to the new system. If the response has not been received yet and the proposal in actual, please, use the new system to send the proposal again.

The discussion of your ideas will be in comments mostly. Perhaps at a later stage it will be a possibility to communicate with the coordinator through any messenger.

Please be active, respond to coordinators' questions in time, make the proposed changes quickly. Remember that Codeforces coordinators are very experienced as participants and as reviewers . Their opinion is important, always balanced, and they have the highest priority in any decisions on the problems.

When the work goes to the preparation of problems in Polygon, the pre-read the examples of well-prepared problems, read all articles about using testlib. It is not difficult, but once you understand, you will be able to prepare high-quality problems for any Olympiad!

Conclusion

Later we come up with how to adapt the system for educational rounds (they come back!), for educational problems. With the new system we will get rid of lost proposals and can significantly automate and organize the process of working with them. I am sure that the system will be upgraded in the future and will become more flexible, more comfortable, more functional.

I hope that in 2017 we will host a lot of interesting rounds with your help. I hope you are waiting for them as well as I'm waiting!

MikeMirzayanov

Read more »

 
 
 
 
  • Vote: I like it  
  • +730
  • Vote: I do not like it  

By MikeMirzayanov, 6 months ago, translation, In English,

Somehow it turns out that for me, each coming the New Year means more and more. This is an excellent opportunity to take stock, to breathe fresh air and to go through a kind of catharsis. This is a rare opportunity to be with the family, dress up in Santa Claus and just have fun.

Holidays give me a clear criterion that I do the right things. If during the holidays, I begin to think about it, to recall some deferred ideas, eager to implement something new. So I’m doing right things. My things. And now exactly the same as in several recent years: during New Year holidays I write code for Codeforces, trying new technology or simply I’m making minor changes in testlib. It is necessary to me: at this moment are no deadlines, do not press the obligation. Just now, at 3 am, I can not break away from being able to do something new. I would like to take a moment and realize that spun in my head the whole year.

I'm insanely happy to huge number (9144!) of registrations on Good Bye 2016. Your desire to grow, to learn new things, solve problems and invent, improve skills and compete, all this things give me strength and desire to develop the platform.

I wish you not to lose the fire in eyes, when you meet an interesting problem. I wish to continue to find pleasure in each contest or round. I wish to find, to solve more and more complicated and interesting problems. Victories and achievements! Wish you to solve all things which you didn’t solve in 2016!

Happy New Year!

But you, please read this post entirely. It is important to me. It draws the symbolic line to me and the whole Codeforces team. And, of course, below it is written about change handles gift and a colorful masquerade of ranks. Go!

Read more »

 
 
 
 
  • Vote: I like it  
  • +1405
  • Vote: I do not like it  

By MikeMirzayanov, history, 6 months ago, translation, In English,

Hello, Codeforces!

I want to test the system before Good Bye 2016, to be sure that everything works as expected.

I invite you to take part in Testing Round #13. It will start soon, on December, 29, 09:05:00 (UTC). It will be unofficial unrated round. The duration is 75 minutes.

Pretests are unusually weak to trigger more hack.

You may expect interactive problems. Hope for hacks for them.

Thank you,
MikeMirzayanov

UPD: Many thanks to all the participants. It seems the system works as expected. We are ready to host Good Bye 2016!

Read more »

Announcement of Testing Round #13
 
 
 
 
  • Vote: I like it  
  • +139
  • Vote: I do not like it  

By MikeMirzayanov, 6 months ago, translation, In English,

Hello, Codeforces.

Codeforces Round 389 (Div. 2) will start on December 25 (Sunday), 09:05 (UTC). It will be based on Technocup 2017 Elimination Round 3. So, if you are a Russian-speaking high-school student, please take part in the Technocup 2017.

Many thanks to KAN, fcspartakm, Endagorion, Kostroma and Golovanov399 Hope to extend the list soon because of testers. Also some problem ideas are mine.

I hope you will like problems. It will be 6 problems.

Wish you good luck and bugless code

UPD: The scoring is 500 - 1000 — 1500 — 2000 — 2500 — 2500

Read more »

 
 
 
 
  • Vote: I like it  
  • +181
  • Vote: I do not like it  

By MikeMirzayanov, 7 months ago, translation, In English,



Hello all.

This coming February of 2017 will be a new experience for me: I'll be one of the coaches who will teach at the Barcelona ACM-ICPC Bootcamp hosted by Harbour.Space University. In addition, here are some well-known coaches from our community: Endagorion, GlebsHP, Michael, Jacob and snarknews. The camp will be hosted in collaboration with Moscow Workshops ACM ICPC by MIPT. The same proven effective studying techniques will be used at the Barcelona Bootcamp.

For me, it will be the first teaching experience outside of Russia as well as my first trip to Spain. I’ll do my best to coach you how to solve problems in an efficient fashion. Also, it will be an excellent chance to communicate about Codeforces personally with the real users.

Hello Barcelona Programming Bootcamp, in collaboration with Moscow Workshops ACM ICPC, is an opportunity for teams of different levels to prepare for successful participation in ACM ICPC. The Bootcamp will be split in two divisions:

  • Division A. Designed to prepare students to excel and win medals in the next ACM-ICPC World Finals.
  • Division B. Designed to help teams prepare for the next season of ACM ICPC Regionals and international competitions. This is an appropriate introduction for teams and students new to the world of ACM ICPC and competitive programming competitions in general. The Division B curriculum features thematic lectures and contests.

The participation fee is €1270 per person (cultural programme, accommodation and meals included). The location in Europe gives the effect of the rather high cost. Anyway, the event is non-profitable for these reasons: To prepare world-wide teams for ACM-ICPC and to scale Russian expertise of coaching on other countries.

The Bootcamp will start on February 6th and will last for 9 days to February 14th. If your team (or you individually) is interested to take part, please register before December 24th, 2016 by the link (discount 20% for registration in time):

Register
to Barcelona ACM-ICPC Bootcamp

You can ask any questions by email hello@harbour.space

Hope to meet you on the Bootcamp,
MikeMirzayanov

Read more »

 
 
 
 
  • Vote: I like it  
  • +173
  • Vote: I do not like it  

By MikeMirzayanov, 7 months ago, translation, In English,

Good afternoon.

Sorry. Unfortunately, today (on Friday) we can't run the round 383 :-(

In short, this is because of technical reasons. For those interested in a more detailed description option.

On Thursday night I got sms. It was written that on server for DB backups free HDD space is less than 10%. This server stores three copies of the database over the last three days. It has 2TB drive and Codeforces database over 600GB now.

Since the next day I had planned to spend on the train on the way to NEERC, I decided to delete some redundant data from the DB. I estimate it will give several tens of gigabytes of free space.

I run query to remove redundant data and it was a mistake. I seems because of huge table to update (tens millions of rows) estimated time for the query to compete was at least several hours. As a result, I have killed this query, making KILL QUERY. But the database has continued to lag, I decided to restart it. Operation to shutdown the DB hanged for ~2 hours (I think it was rolling back the transaction), and the DB has stopped to respond and has become quite sad. As a result, I killed the DB process in the operating system and the database already refused to start without a recovery operation, which is also wasn't completed in a couple of hours. In short, I have struggled with this from 5 am to 9 am.

To make Codeforces live I reconfigured it to use database replica in the remote datacenter (in Mail.Ru). Before boarding the train, I started the process of transferring data from the replica back, but contrary to my expectations, this process has been very slow.

It is impossible to run the round using a remote reserve database server. Therefore, we have to move the round forward to Tuesday.

My apologies. I spent many hours struggling with technical issues and worked up to the last. However, it seems the bottleneck is in speed of data transmission over a network, in the speed to write on HDD and in the speed of innobackupex utility.

I hope that on Tuesday everything will go fine!

MikeMirzayanov

Read more »

Tags 383
 
 
 
 
  • Vote: I like it  
  • +486
  • Vote: I do not like it  

By MikeMirzayanov, history, 7 months ago, In Russian,

Добрый день.

Сначала я хотел написать комментарий. Его стал писать принимая пересдачу у студентов, увлекся и текст вырос до размера поста.

Контест такой: Михаил MikhailRubinchik Рубинчик как-то написал пост про архивы, где он поставил под сомнение целесообразность использования архива задач Codeforces как архива задач в отличии от Тимуса. Еще в комментариях вот к этому посту была тема поднята. Сам я трепетно отношусь к Тимусу, мой старт в олимпиадах был во многом связан с решением задач оттуда (правда больше контестов, чем архива), но такая позиция мне не очевидна.

Вероятно, Михаил недостаточно внимательно посмотрел на возможности Codeforces. Возможно, что ему удобно рекомендовать Тимус для своих студентов, так как многие задачи оттуда он помнит, лично знает авторов, у него уже десяток студентов, нарешавших там около 1000, может имеет какой-нибудь админский доступ туда или хотя бы прямой выход на админов. Если так, то я его в этом отлично понимаю, сам по этой причине часто рекомендую к прорешке хорошо знакомые мне ресурсы.

В списке ниже я попробую раскрыть тему, какие усилия приложила команда Codeforces, авторы задач и сообщество, чтобы ценность Codeforces как архива была значительная, буду сравнивать с Тимусом (не я поднял эту тему!). Если я отстал от того, что умеет Тимус, пожалуйста, поправляйте меня.

  • На Codeforces задачи покрыты тегами. Часто бывает, что прорабатываешь какую-то тему и хочется решать тематические подборки задачи. На Тимусе я вижу какое-то непонятное упоминание Метки: нет (скрыть метки для нерешенных задач). Что это для меня загадка. UPD: я нашел что это, но видимо метками покрыта лишь часть задач.
  • На Codeforces все задачи специально разработаны для раундов, а вот на Тимусе есть задачи с хороших командных контестов, которые потом неплохо бы потом прорешать командой.
  • На Codeforces значительно шире круг авторов, на Тимусе очень много задач уральских авторов. Это накладывает отпечаток на тематику и типаж задач.
  • На Codeforces наверняка в среднем лучше тесты просто благодаря наличию взломов. Я каждый контест убеждаюсь, что как бы ни старался автор обязательно найдутся какие-то взломы, которые улучшают набор тестов.
  • На Codeforces практически к каждой задаче можно найти разбор и почитать её обсуждение в комментариях. На Тимусе есть форум, но я случайно потыкал в задачи — кажется, дельных обсуждений там меньше и читать его сложно.
  • На Codeforces полезно после решения задачи посмотреть решения крутых участников и чему-то научиться (подсмотреть трюк в реализации, другую идею). На Тимусе такой возможности нет.
  • На Codeforces каждая задача принадлежит недлинному контесту и при желании сначала можно решить виртуальное соревнование, которое её содержит, а потом только перейти к дорешиванию. Что полезно: не важно решали вы эту задачу в архиве, мэшапе, виртуальном контесте или настоящем — она будет помечена у вас как решенная.
  • Codeforces значительно лучше подходит для совместной работы. Наличие списков пользователей позволяет быстро и просто для группы тренирующихся находить ранее нерешенные задачи. Если вы решали какой-то контест командой, то задача у вас будет отмечена как решенная.
  • Наличие большого количества задач — это конечно плюс. Довольно странно ставить в заслугу "Зато на Тимусе задач меньше!". Если слишком разбегаются глаза, то можно решать только задачи из старых контестов (с номерами до 200, например). С другой стороны, если вы выбираете задачи какой-то определенной сложности или тематики, то выбор остается не слишком узкий.

Есть еще несколько моментов совсем уж на грани просто моего ИМХО — условия из простыней текста в некоторых задачах, условия только на английском, много задач с одним тестом и без пояснений.

В общем, тезис из поста Михаила мне не кажется каким-то значительным, а вот многие пункты перечисленные выше как минимум могут быть полезны.

С радостью послушаю мнение любителей архивов, где я ошибаюсь или что можно улучшить в этом направлении на Codeforces (сам я, конечно, вижу ряд пунктов).

Read more »

 
 
 
 
  • Vote: I like it  
  • +98
  • Vote: I do not like it  

By MikeMirzayanov, 7 months ago, translation, In English,

Good afternoon!

I've decided to share my thoughts on the round 382.

Of course, it turned upset not only to me, but also to the round coordinator GlebsHP.

In this round the main negative feedback were caused by two problems: 735D - Taxes and 735C - Tennis Championship.

Regarding 735D - Taxes. I do not share the criticism to this problem. In fact, to solve it would be nice to be familiar with Goldbach's Conjecture and better with Prime Number Theorem. These facts are medium-popular in the world of programming contests. Familiarity with them is useful, gives useful insight into primes. It is important: in this problem it was necessary to perform a simple, but nevertheless, additional step to find solution. It seems to me that it's okay to use problems that have a reduction to some popular and semi-popular topics. Otherwise, it is thrown away a huge number problems.

As a summary for this problem. I agree that the problem 735D - Taxes is not an example of the best problem. But it has a right to exist as one of the problems in a round. It can not take a role of any argument in favor of unrated round. I personally, would not include it in my contest. But the fact of the use of the Goldbach's conjecture (and more prime number theorem) is not a reason for me to convict and forbid a problem.

The situation with the problem 735C - Tennis Championship is much more complicated. It is necessary not to mix the two fundamentally different reasons for occurrence of same problems:

  • Problems can be matched randomly, inadvertently. Of course, the coordinator and testers always have a critical look on the problem. At the stage of the contest preparation they immediately react if a problem is familiar to somebody. It is important to understand, that huge number of problems have been invented over the years of existence of sports programming. It is physically impossible to be familiar even with a large part of them. No matter how experienced the jury, sometimes, coincidences happen. Note that if the round is not a stage of a championship and its results do not affect prizes the main reasons for participation in it should be self-development and a desire to get a fan from the competition. None of these goals encourage search in Google.

  • Deliberate coincidence or reuse of problems, it is a different story. And here it is what happened. This situation is totally unacceptable (educational rounds do not count), it is necessary to fight with it and to respond rapidly to incidents.

As soon as I examined about the incident, immediately called by phone the writer and discussed (and denounced) the situation. I explained the inadmissibility of such cases and their implications. I think Albert made the correct conclusions and will be accurate in future. Unfortunately, I was informed about incident only after the ratings been updated.

Taking into account large number of participants who didn't notice the issue, who solved problems completely independently, who were happy of upset by their rating changes, shared their results in social networks it does not seem respectful to do to them unrated. I share the view that it would be better not to be so, but history has already taken place. Note that if I learned the situation during the round or immediately after, the outcome might be different. I think it's a good idea to report suspected cases through questions to give a chance the coordinator or me react quickly.

As a conclusion, I do not propose to raise the tragedy, coordinators do not despair. The writers, of course, need to understand the responsibility and importance of taking on the role. Thousands of participants come to solve your problems and, of course, expect something interesting and new.

I urge the community not to forget about respect for the work of authors: to prepare the contest is a big and difficult task. The author takes on a difficult role and if a round took place, so the hard way from the idea to the final implementation has done. Please, be grateful for it, say the authors, coordinators and testers, thank you!

Whatever effort the Codeforces team makes, we can not do rounds without the writers. Therefore, we look forward to your problems. Hope to see good and bright rounds here!

Thank you for attention,
MikeMirzayanov

Read more »

 
 
 
 
  • Vote: I like it  
  • +1288
  • Vote: I do not like it  

By MikeMirzayanov, history, 7 months ago, translation, In English,

Hello, my dear lovers of algorithms and data structures.

Codeforces Round 380 will start on November 20 (Sunday), 09:05 (UTC). It will be based on Technocup 2017 Elimination Round 2. So, if you are a Russian-speaking high-school student, please take part in the Technocup 2017.

Many thanks to KAN, GlebsHP, fcspartakm, Levshunovma. Hope to extend the list soon because of testers. Also some problem ideas are mine.

I hope you will like problems. It will be 6 problems in each division.

Good luck and bugless code

Scoring:

  • TK Elim 2 and Div 2: 500-1000-1750-1750-2000-2500
  • Div 1: 750-750-1000-1500-2000-2500

UPD 1: Here are our winners!

Top-5 in the Technocup stage:

  1. sslotin
  2. Arthur_
  3. hloya_ygrt
  4. asokol
  5. Denisson

Top-5 in Div.1:

  1. AlexDmitriev
  2. MrDindows
  3. Belonogov
  4. doreamon
  5. LHiC

Top-5 in Div.2:

  1. Road_to_master
  2. Muddlealong
  3. vietthangcvp
  4. kongroo
  5. meeeep

Read more »

 
 
 
 
  • Vote: I like it  
  • +227
  • Vote: I do not like it  

By MikeMirzayanov, history, 7 months ago, translation, In English,

Welcome to 2016-2017 CT S03E09: Codeforces Trainings Season 3 Episode 9. The training duration is 5 hours. It is opened for teams as well as for individual participants. After the end you may use the practice mode to complete problem solving. Also it will be available as a virtual contest for whose of you who can't take part today. Please, do not cheat. Only fair play!

Visit Codeforces::Gym to find the contest and register.

We are planning to start on November 9, 2016 13:10 (UTC).

It is possible that the problems will be too easy for some participants, it is possible that we will add some problems.

Good luck!

Read more »

 
 
 
 
  • Vote: I like it  
  • +71
  • Vote: I do not like it