By M.Mahdi, history, 5 years ago, In English

Hi everyone!

On-site competitive programming competitions are rare and valuable events, and we all practice hard to have great competition. But I guess we are missing a point. One notable opportunity that exists in these kinds of events is getting to know other members of the competitive programming community, more than what we see in the scoreboards. The lunch club was a cool way of using this opportunity. (scott_wu, are we going to have the club this year? )

I remember the last day of IOI 2017. After everything was finished and the medals were given, I went back to the hotel and I saw an unexpected scene. I found there is this cool tradition in IOIs that in the last day contestants gather together, take pictures, and give out souvenirs. (FYI, I wasn't an IOI participant, I was in the host scientific committee.) I still have the souvenirs that I got from Japanese and Chinese contestants, and It encouraged me to search and get more familiar with their cool cultures.

So, in the remaining days before the trip to Portugal, I'm going to buy some souvenirs to give out in the world finals. I guess we can do this after dinner on the last day, in the lobby of the hotel. I'd be glad if you come and get it!

If you are interested, join the club and bring something from your country for everyone! Maybe this way, we start the tradition of bringing souvenirs to the world finals.

UPD: As stated here, the meeting is better to be in the farewell dinner hall instead of the hotel lobby. So we'll meet in Alfândega — West Ground Floor on Thursday. We will need to bring our souvenirs when leaving the hotel in the morning because we will go directly to the closing ceremony and celebration dinner from the contest. Please let your friends know the change so that no one misses the gathering.

UPD2: Don't forget your souvenirs tomorrow!

Good luck in the contest. :)

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By Errichto, 5 years ago, In English

Hi.

On Wednesday at 9:05 CET / 8:05 UCT you can participate in the GYM version of the finals of 2017-2018 Russian Olympiad in Informatics (ROI), Day 1. And on Thursday there will be day 2, same time.

Links to GYM contets: day1 and day2.

5 hours, 4 problems, IOI-style scoring with subtasks. Statements will be available in three languages: English, Russian, Polish.

We wanted to use those problems in a camp in Warsaw so we had to import the problems to some system anyway. Then why not Polygon+Codeforces and thus allowing everybody to participate? Huge thanks to MikeMirzayanov for helping me with using GYM.

And credits to problem authors: Andreikkaa for Radium, Endagorion for Viruses, pashka for Innophone, Георгий Корнеев and GlebsHP for Quantum Teleportation.

Second day authors: cdkrot for Decryption, "jury" for Quick Sort, GlebsHP for Robomarathon, Endagorion for Addition without carry.

I will post a very short editorial in English here, after the contest.

Extraction of radium
Innophone
Quantum teleportation
Viruses

Second day tomorrow, same time.

Thank you for participation.

Addition without carry
Decryption
Quick sort
Robomarathon

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By MikeMirzayanov, 5 years ago, translation, In English

Hi Codeforces!

Here are some recent improvements here and in Polygon.

Weak and Leaked Passwords

We often hear about password leaks from various services. Considering that having common passwords is a common (but insecure) practice, we've improved Codeforces and Polygon to identify weak or leaked passwords. If on the top of the website you see a message that your password is not secure, then just change it immediately.

Type of the round when creating a contest proposal

This item improves our work with the writers. When creating a contest proposal, please indicate the type of a round. Leave the field empty only if you don't know the type of the round (it is strange).

Calendar

We've fixed errors when synchronizing official Codeforces rounds with the calendar. Now everything should be correct.

I trust this user

Currently, Codeforces provides a mature infrastructure for organizing contests, olympiads and trainings. With the help of domain groups and mashups, competitions of various levels were hosted on Codeforces. The organizers are sometimes not regular users of Codeforces rounds and do not have rights to some of the actions. Now, any red user can confirm his trust in another account, and he will get the right to: write comments/posts, create private groups, create mashups. I hope this will save me from a certain routine of processing such requests.

Confirmation via email when entering Polygon

When you sign in Polygon, your IP-address and browser will be verified. If you didn't use them in the recent past, then you may be asked to sign in with a confirmation email. In this case, just follow the secret link that comes to your email.

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By awoo, history, 5 years ago, translation, In English

Hello Codeforces!

On Mar/22/2019 18:05 (Moscow time) Educational Codeforces Round 62 (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 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 participants!

Our friends at Harbour.Space also have a message for you:

Hello Codeforces!

We want to remind you about the two fully funded scholarships we currently have available:

Master’s in Data Science Scholarship & Master’s in Robotics Scholarship

Both scholarship opportunities include: - Full coverage of the Programme’s tuition fee (€23,000 value) - 3 hours of study a day at Harbour.Space University - 4 hours of internship a day with one of our industrial partners - €12,000 euros a year (living allowance)

If you’re interested in applying for the Robotics Scholarship, apply here.

If you want to apply for the Data Science Scholarship, fill out the form below and we will contact you about the next steps.

GO TO FORM

If you need more information about either, please contact us at [email protected]

Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 QDEZ604 7 250
2 dotorya 7 254
3 300iq 7 586
4 dreamoon_love_AA 6 165
5 Hazyknight 6 169

Congratulations to the best hackers:

Rank Competitor Hack Count
1 Haunted_Cpp 8
2 Tqk 4
3 Jobaidul 3
4 Abu_Musa_99 3
5 yahia 2
37 successful hacks and 149 unsuccessful hacks were made in total!

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

Problem Competitor Penalty
A Sonechko 0:01
B usertab34 0:04
C KhaleD_ 0:04
D edisonhello 0:02
E Roundgod 0:23
F QDEZ604 0:38
G 300iq 0:44

UPD: Editorial is out

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By Jeel_Vaishnav, history, 5 years ago, In English

Hi everyone!

I would like to invite you to my second Codeforces round, which I have created with my friends Ashishgup and Vivek1998299.

With that said, I bring to your attention our new Codeforces Round 548 (Div. 2) that will take place on Mar/21/2019 18:35 (Moscow time). If your rating is less than 2100, this round will be rated for you; otherwise, you can participate out of competition.

I would like to thank Ashishgup and Vivek1998299 for their help with preparing problems, vintage_Vlad_Makeev, mohammedehab2002 and Um_nik for testing the problems and cdkrot for coordinating our round. I would also like to thank MikeMirzayanov for the awesome Codeforces and Polygon platforms.

You will be given 6 problems and 2 hours to solve them. Scoring distribution will be announced later.

Good luck! :D

UPD1: Shortly after the contest, we'll be on the community Discord server to discuss the tasks.

UPD2: Score distribution is — 500-1000-1750-2250-2500-3000

UPD3: Editorial

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By MikeMirzayanov, 5 years ago, translation, In English

Hello, Codeforces!

I am pleased to invite you to Codeforces Round 547 (Div. 3), which will start on Mar/19/2019 17:35 (Moscow time). Everyone whose current rating is strictly less than 1600 is invited to participate officially. All others can take part out of the competition.

It so happened that the schedule of this month is not replete with rounds (coordinators, we hope for you!). Therefore I decided to partially correct the situation. All the problems of this round were invented and prepared by me on the last day of Hello Muscat Programming Bootcamp 2019 and on flights from Muscat to St. Petersburg. I even specially noted the time for preparation: for the current moment (the problems are ready for testing) I spent about 6 hours on their preparation, including inventing some of the problems. I really like working on problems, this is something at the intersection of creativity and programming. I really hope you enjoy the result of my work.



I am in Oman while writing the problems for the round.

The round will be hosted by rules of educational rounds (extended ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over. You will be given 6-8 problems for 2 hours to solve them.

Note that the penalty for incorrect submissions in this round is 10 minutes.

Remember that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted participants of the third division, you must:

  • take part in at least two 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.

I hope a little later a list of thanks to testers will appear instead of this paragraph. So far I only plan to give the round to testing. Many thanks to the testers ivan100sic, KrK, Benq, I_love_Tanya_Romanova, nhho! UPD: And extra thanks to more testers Pavs, awoo, Narts, anon20016, Stresshoover, Ivan19981305.

Good luck on the round
MikeMirzayanov

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By MikeMirzayanov, 5 years ago, translation, In English

Hello!

We supported the rendering of LaTeX-formulas with MathJax in new posts and comments. Now the formulas will be as beautiful as in problem statements. Drawback: they are displayed not immediately, but redrawn after the page is displayed. Old posts and comments are displayed in the old way (already a lot of old content, backward compatibility is very important). Note that if you edit old post, it will still be displayed in the old style.

Here are some example: $$$1 \le n \le 10^{12}$$$,  $$$c = \sqrt{a^2+b^2}$$$,  $$$i\hbar\frac{\partial}{\partial t}\left|\Psi(t)\right>=H\left|\Psi(t)\right>$$$.

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By gop2024, history, 5 years ago, translation, In English

Hi, Codeforces!

I`m glad to invite everybody to the #546 Codeforces round, which will be held on Monday, March 11, 2019 at 19:35. The round will be rated for all participants from the second division (with rating below than 2100). As usually, we will be glad to see participants from the first division out of competition!

Problems for the round have been proposed by Fedor ---------- Ushakov, Stepan IbragiMMamilov Stepkin, Alexey usertab34 Roze, Denis Denisson Shpakovskij and Alexander Ralsei Gladkov.

The round have been prepared by us, Dmitry gop2024 Grigoryev, Fedor ---------- Ushakov, Semyon cookiedoth Savkin and Dmitry TheWayISteppedOutTheCar Piskalov.

We'd like to give thanks to Ildar 300iq Gainullin for excellent coordination of the round, Grigoriy vintage_Vlad_Makeev Reznikov, Alexey Aleks5d Upirvitsky and Mohammed mohammedehab2002 Ehab for testing and to Mike MikeMirzayanov Mirzayanov as well for his unbelievable Codeforces and Polygon platforms.

You will receive 5 problems and 2 hours for solving it. During the round you will be helping for an extraordinary girl Nastya, who is studying in an usual school in Byteland.

Score distribution will be announced, traditionally, closer to the start of the contest.

Please, read all the tasks. Good luck!

UPD Score distribution is standart — 500-1000-1500-2000-2500

We're looking forward your participation.

UPD2 Thank you for your participation in the contest!

List of the winners of the contest:

Div.2

  1. woookje

  2. 1021869

  3. stanislav.bezkorovainyi

  4. Hamzqq9

  5. ilyausmanov

Div.1 + Div.2

  1. kmjp

  2. step_by_step

  3. TangentDay

  4. ..vince

  5. hitman623

My frank congratulations for all the winners!

The editorial will be posted very soon. We apologize for delay.

UPD3

The editorial

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By cdkrot, 5 years ago, translation, In English

Hello!

Right now happens the first tour of the Open Olympiad in Informatics, and tomorrow will be the second one. This contest is prepared by Moscow Olympiad Scientific Committee that you may know by Moscow Team Olympiad, Moscow Olympiad for Young Students and Metropolises Olympiad (rounds 327, 342, 345, 376, 401, 433, 441, 466, 469, 507, 516, 541)

Open Olympiad consists of the most interesting and hard problems that are proposed my a wide community of authors, so we decided to conduct a Codeforces regular round based on it, which will happen Mar/08/2019 12:05 (Moscow time) and will be based on both days of the Olympiad. Each division will have 6 problems and 2:30 hours to solve them.

We kindly ask all the community members that are going to participate in the competition to show sportsmanship by not trying to cheat in any manner, in particular, by trying to figure out problem statements from the onsite participants. If you end up knowing some of the problems of Moscow Open Olympiad (by participating in it, from some of the onsite contestants or in any other way), please do not participate in the round. We also ask onsite contestants to not discuss problems in public. Failure to comply with any of the rules above may result in a disqualification.

Problems of this competition were prepared by vintage_Vlad_Makeev, isaf27, Flyrise, cdkrot, GlebsHP, ch_egor, Zlobober, qoo2p5, grphil, achulkov2, Schemtschik, akvasha, mingaleg, V--o_o--V, wrg0ababd, guided by ch_egor, cdkrot, GlebsHP, Zlobober and Helen Andreeva.

Problems for second division were prepared by KAN and MikeMirzayanov, to who we also want to say thanks for the Codeforces and Polygon systems.

Good luck everybody!

UPD: Congratulations to the winners!

Div.1

  1. sunset
  2. Petr
  3. Radewoosh
  4. ko_osaga
  5. orbitingflea

Div.2

  1. appplese
  2. al3xstr33t
  3. Charlene_Hao
  4. ytxytx
  5. QDEZ604

The editorial will appear soon

UPD: The editorial

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