Hello, Codeforces!

“Experimental Educational Round: VolBIT Formulas Blitz” will take place on February 18, 2016 at 18:00 MSK. This time the problemset is recommended for Div.2 participants.

The round will be unrated for all users and it will be held according to the standard ACM-ICPC rules. You will have 180 minutes (three hours) to solve 18 problems. There will be no open hacks phase after the round.

Our main target audience is beginners and Div. 2 members. All offered problems can be solved without conditional constructs and without loops. Only formulas are required. Assignments and functions can be used to reduce code duplication.

The topics of the problems are:

• combinatorics
• geometry
• game theory
• sequences
• other

The round is created as a part of Vologda BIT event, also as part of this event “Contest programming from zero in Java” webinars were held devoted to the topics listed above. Recordings of the webinars are available on YouTube (in Russian).

The round was prepared by me, Fyodor Menshikov mfv, Igor Andrianov igand and Oleg Strekalovsky OSt. Special thanks to Maria Belova Delinur for bugfixing the English statements and of course to MikeMirzayanov for Codeforces platform and Polygon. Polygon made our checkers and tests for this contest better.

UPD: The editorial is complete.

Hello,

As you might remember, CodeCraft 2016 was held online on the university's platform on 12th Feb 2016(find announcement, results). CodeCraft is an 5 hours ACM-ICPC style contest for individuals which is organised every year by IIIT Hyderabad. We don't have resources to keep our platform online for whole year, so we think GYM contest is a good option to create an archive and help people train better.

I invite you to GYM Replay of the contest to be held on 21st Feb 2016 1400 MSK in GYM. There will be 12 problems and duration 5.5 hours(as was original contest).

There are some really interesting problems in contest. In general, all participants would be able to find something that captivates their interest. For a better gradient, the level is a letter higher than last years contest. Also, you'll be able to compete with ghost participants(i.e. participants who actually participated in original contest).

Detailed editorials will be uploaded once the GYM contest is over.

Good luck and have fun!

UPD: Editorial

Hello everyone! The first round of the 8VC Venture Cup will be held on Saturday, February 13th at 12:35PM EST. ecnerwala and I are the problem setters. We want to thank GlebsHP for his help in preparing the contest, Delinur for translating the problems, and MikeMirzayanov for creating the Codeforces platform

The contest is for competitors in both divisions and contains seven problems. The scoring distribution is as follows:

500 — 750 — 1000 — 1500 — 2000 — 2500 — 3000

The contest will be slightly longer than usual — two and a half hours. The top 200 contestants will advance to the final round, and the top 20 local finishers will be invited to Woodside, CA to compete onsite. Good luck!

UPD: System testing is now over. Congratulations to the top contestants:

1. Petr
2. jqdai0815
3. ilyakor
4. bmerry
5. Errichto

The top 200 contestants will advance to the final round in two weeks. Congratulations!

The editorial can be found here.

Hey Codeforces!

I’ve worked with Addepar and the broader 8 | family of companies in Silicon Valley throughout 2014 and 2015, and it’s been an excellent experience. I would encourage everyone in the community to learn more about the great work that these companies are doing and I’m happy to announce that 8 | Partners will be hosting the 8 | VC VentureCup on Codeforces! It’ll be a fun contest and I’ve worked on the problems along with a few competitive programmers in our network. The contest will begin on February 13 and consist of two rounds.

ABOUT 8 | PARTNERS

8 | Partners, 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 those featured below, and a host of other top technology platforms that leverage modern algorithms and data science to power their core business processes.

SELECT 8 | FEATURED COMPANIES

If you’re interested in job opportunities with these companies or others in the 8VC portfolio, contact us below!

THE CONTEST

The contest will occur in two rounds:

Round 1 is online and takes place on February 13. Round 1 follows regular Codeforces rules and consists of 7 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.

Round 2 takes place on February 28, consists of 5 problems, and uses regular Codeforces rules. The complexity of the problems is higher than a regular Codeforces round. We will invite the top 20 local finishers in Round 1 to Woodside, CA to compete in Round 2. In addition, we will invite the top 200 overall finishers to compete online.

PRIZES

• Overall 1st place — $2500
• Overall 2nd place — $1000
• Overall 3rd-5th places — $500 each
• Overall 1-50th place — t-shirts with 8 | VC and company logos
• Local Winner — Dinner with Joe Lonsdale (founder of Palantir, Addepar, & 8 | Partners) and other Silicon Valley technologists
• Local top finishers — Opportunity to meet with leadership from 8 | VC portfolio companies

Good luck!

Hello, Codeforces!

Educational Codeforces Round 7 will take place on 10 February 2016 at 18:00 MSK for the first and second divisions. You can read about educational rounds here and here.

<This paragraph was modified last time>

The round will be unrated for all users and it will be held with extented ACM ICPC rules. You will have two hours to solve six problems. After that you will have one day to hack any solution you want. You will have access to copy any solution and test it locally.

If you have ideas for some problems or maybe already prepared problems that you can't use in rounds or official competitions, you can write to me.

</This paragraph was modified last time>

Thanks a lot to Aleksa Plavsic allllekssssa who suggested the problems D, E and Ivan Popovich NVAL for the problem F. Also thanks to Mohammad Nematollahi Deemo who suggested the problem that was highly simplified and will be under the letter C.

The round was prepared by me, Edvard Davtyan. Thanks a lot to MikeMirzayanov we invented the problems A, B and C together. Also thanks to Maria Belova Delinur for checking the English statements, Aleksa Plavsic allllekssssa and Ivan Popovich for testing the problems.

We tried to make the problems easy but interesting. I think that the problems is mathematized a little. I hope you will enjoy the problems!

Good luck and have fun!

P.S.: The Codeforces Educational Rounds was recognized by Snarknews as the best project in competitive programming in 2015 (the picture below is the prize).

UPD1: The first phase of the contest is ended. You can hack any other solution.

UPD2: The editorial is ready.

UPD3: The round is over, the results is final.

Hello, community!

Tomorrow Codeforces Round #342 is going to take place. It will share the problemset with Moscow Olympiads in Informatics for students of grades from 6 to 9. Though, grades from 6 to 9 in Russia usually match the ages from 12 to 15, I guarantee that everyone (even Div. 1 participants) will find some interesting problems to solve. Problems were selected for you by the Moscow jury team: Zlobober, meshanya, romanandreev, Helena Andreeva and me; and prepared by members of our scientific committee: wilwell, Sender, iskhakovt, thefacetakt and feldsherov.

Scoring distribution will be quite unusual: 750-750-1000-2000-3000.

UPD System testing is over. Here are the top 10:

1. _XuMuk_
2. pandamonium
3. latisel
4. zetamoo
5. yukariko
6. I_Love_Ximera
7. kittylover
8. shdut
9. harry.zhao
10. luke0201

Congratulation! Also, problems seemed to be too tough, we should have probably made Div. 1 round. Anyway, thanks for participating, I hope you enjoyed it and learned something new!

Thanks to romanandreev for nice analysis.

Hi, Sharif University of Technology is holding an international AI competition. You may read a short description about it below:

=========

Student Scientific Chapter of computer engineering department at Sharif University of Technology will hold the first international Sharif Artifical Intelligence Challenge on March 2nd and 3rd.

This competition will be held in two phases including an online and an on-site phase in which competitors will compete in teams of three in a game designed by our technical team.

The only pre-requisite to enter this competition is familiarity with programming using C++, Java or python. But obviously, knowledge of algorithmic thinking and artificial intelligence will be a great asset for any of the participating teams. The registration for online competition is free and open from february 1st through to february 8th available at http://aichallenge.sharif.edu .

After finishing the online phase which starts on February 9th and continues untill February 17th we will run submitted codes and teams with highest scores will make it to on-site competition. Winners of on-site competition are awarded. For further news and announcment please checkout our blog at http://aichallenge-en.blog.ir or follow @aichallenge on twitter and instagram.

THE COMPETITION IS FIERCE.

=========

UPDATE #1: On-line competition is open to everyone however to participate in the on-site contest you have to be a student. You may participate in the on-line competition with a team of at most three members however participating in the on-site contest requires a team with exactly three members.

Hi, Codeforces!

AIM Tech Codeforces Round will take place on February, 4 at 20:05 MSK.

The round is prepared by AIM Tech employees: Kostroma, riadwaw, yarrr, ArtDitel, ValenKof, bobrdobr, agul, gchebanov and zeliboba. Round will take place during Petrozavodsk Winter Camp, which is sponsored by our company.

We made our problems a little easier than at our last Round, but we promise they won’t be less interesting. Scoring system will be static. The final distribution of points will be announced right before the round, however you should note that this time difference in complexity between problems div1 C, D and E may be less than usual so our strong recommendation that you read them all first.

Thanks to Mike Mirzayanov(MikeMirzayanov) for brilliant platforms Polygon and Codeforces, problem coordinator Gleb Evstropov (GlebsHP) and Maria Belova (Delinur) for English translation.

Our company specialises in proprietary trading, the key concepts in our work are big data, low latency and high frequency. Our team mainly consists of graduates from the MSU Faculty of Mechanics and Mathematics and Moscow Institute of Physics and Technology (MIPT).

We wish you good luck and high frequency rating!

P.S. For all participants of PTZ gathering we are glad to announce evening buffet that will take place at Paulaner Brauhaus and will start Februrary, 5 at 7:30 pm

Scoring

div2: 500 — 1000 — 1500 — 2000 — 3000

div1: 500 — 1000 — 1750 — 2000 — 2250

Editorial

P.P.S. Author solution of div2A had precision error 5e-7, so we decided to rejudge this problem.

Hello Codeforces!

I invite all of you to participate in a special Codeforces round. It will take place on 29 Jan, 17:05 UTC. It will not be a usual round. Thanks to Wunder Fund, the best participants will win prizes and souvenirs. Here are some words from Wunder Fund:

Our company is situated in the center of Moscow. We are engaged in high-frequency trading — developing high-performance systems and algorithms for automated trading in financial markets. In this area algorithms and data structures (that you love to invent and implement) are vital. Our systems should process transactions in milliseconds! High-frequency trading is a continuous competition of the best programmers and mathematicians around the world. By joining us, you will become a part of this exciting challenge.

We offer interesting and challenging tasks for the development of low latency for enthusiastic researchers and programmers. Flexible and no bureaucracy, decisions are taken quickly and implemented. We are a small team, so you will immediately become a significant part of it. Understand the economics and finance is not required, but the algorithms and data structures is what we need.

Are Russian speaking and ready to live in Moscow? Join us! Visit our website for more information.

We will be happy to give participants prizes and gifts:

• 1 place — PlayStation 4
• 2 place — Xbox One
• 3-5 places — Sega MegaDrive 16bit with games
• 1-50 places — Wunder Fund T-Shirts!
• 51-500 places — 50 T-Shirts to random participants!

I want to thank the following people for helping me with this round:

• GlebsHP for his help in reviewing problems and assistance in preparation for the round.
• LiChenKoh, AlexFetisov, and winger for testing problems.
• Delinur for translations.
• MikeMirzayanov for Codeforces and Polygon systems.
• and of course Wunder Fund for sponsoring the round.

I hope to see you all at the round. Good luck and have fun! :)

If you'd like some practice before the round, you can look over some of my past rounds that I've written (links here: A B C). I will try to give you all some more interesting problems to solve.

UPD1: The round will be 2 hours and 7 problems. Unfortunately, there are some time conflicts, so we are unable to extend the duration of the round. The score distribution will be 500-1000-1500-1750-2500-2750-3500. Note that some problems that we thought are harder may actually be easier for you, so I encourage you to read all problems.

UPD2: The editorial is published. Congratulations to the winners

1. Egor
2. Petr
3. Um_nik
4. RomaWhite
5. Sampson

Hello.

Now Codeforces will be more convenient to browse from mobile platforms. For the majority of them mobile view is available now. The menu goes to the left panel and sidebar — to the right. Both panels are available either on special icon at the top of the page, or by swipe left/right. You can hide them by touch in the main area of ​​the page, or by reverse swipe. In the mobile view fonts are enlarged, so on most screens it is possible to read the website without zoom.

So, for example, how the sidebar appears on my phone:

You can switch off mobile view (or to switch off) by clicking the special link in the bottom of any page.

P.S. In old browsers, and generally on a non-webkit it may work incorrectly. Not sure it is easy to fix :-(