By Edvard, history, 47 hours ago, translation, In English,

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).

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By GlebsHP, history, 4 days ago, In English,

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.

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By matrix, 7 days ago, In English,

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 .

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 or follow @aichallenge on twitter and instagram.



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.

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By zeliboba, 8 days ago, translation, In English,

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, AlexDmitriev, 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


div2: 500 — 1000 — 1500 — 2000 — 3000

div1: 500 — 1000 — 1750 — 2000 — 2250


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

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By scott_wu, 8 days ago, In English,

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.


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.


Kiwi is a San Francisco-based company making the world's dominant Q&A platform on mobile, defining a new category of interaction. We let users ask questions, publicly or anonymously, of their friends, followers, and other users all over the world. The platform empowers users to generate rich content using pictures, video, or text to express their opinions on the questions asked to them. Kiwi is creating a new type of community, built on shared curiosity from around the globe.

Radius delivers predictive marketing software that transforms the way B2B companies discover new market opportunities, acquire the right customers, and measure success. Using Radius, marketers instantly access unprecedented value with cloud-based software designed for user experience, scalability, and security for organizations of any size – from the Fortune 500 to emerging growth companies. Our software is powered by the Radius Business Graph–a proprietary data science engine fueled by intelligence on every U.S. business–which provides marketers with real-time predictive analytics, powerful segmentation, and seamless integrations to reach all their customers in more meaningful, relevant ways.

Blend is a deep Silicon Valley technology company whose product empowers lenders to originate efficient, data-driven mortgages. Leveraging high-fidelity data sources as well as automated rules and configurable workflows, Blend enables lenders to drive down origination costs and keep airtight compliance while providing their borrowers with an elegant, digital user experience.

Oscar is a new kind of health insurance company, designed to put people first. Through a high-tech, data-driven approach, easy-to-understand language and a unique set of benefits, Oscar is drastically changing the way we think about and interact with our health insurance. Founded in 2012, Oscar makes health insurance simple, transparent and human.

BuildZoom is a marketplace for remodeling and construction services. We're modernizing this $1.2 trillion industry by using the world's largest collection of construction data to objectively rate and rank contractors, making it easy for homeowners, businesses and construction managers to find the best fit for any project. We then offer collaboration tools to help people manage the entire project in a simple and straight-forward manner. Since launching in 2013, BuildZoom has rapidly grown into a thriving marketplace that facilitated over $1 billion in projects in 2015.

Color's mission is to democratize access to high-quality genetic information. Color provides a high-quality, physician-ordered, genetic test at a low cost. Color's goal is to expand access to breast and ovarian cancer genetic risk information for every person, everywhere.

OpenGov transforms the way the world analyzes and allocates public money. With more than 700 government customers across 45 states in a rapidly expanding network, OpenGov is the market leader in cloud-based financial intelligence, budgeting, and transparency for government. The OpenGov platform transforms government financial data into intuitive, interactive visualizations for both internal government users and citizens.

Addepar streamlines the increasing complexities of modern investment management into one seamless platform: comprehensive data aggregation, unmatched data integrity, flexible analytics, intuitive reporting, limitless customization and interactive portals. Addepar empowers advisors to increase client satisfaction, business efficiency and business growth.

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

Connect to 8VC


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.

  • 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!

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By memset123, history, 12 days ago, In English,

Hi all! I hope you're having a great day!

On January 31, at 14:05 UTC Codeforces Round #341 (Div. 2) will take place.

The problems were developed by: Shwetark Patel (memset123) and Alex Gu (minimario). We would also like to thank the tester, Daniel Chiu (waterfalls).

We thank Gleb Evstropov (GlebsHP) for his help in preparing the contest, Maria Belova (Delinur) for translating the statements into Russian, and, of course, MikeMirzayanov for unique Codeforces and Polygon platforms.

Round will have standard Codeforces rules, with pretests at first, and final tests afterwards. The hero of this round will be Wet Shark (can you tell me what it means?). Wet Shark is a very tricky shark, so do not be deceived by his tricks.

Scoring will be announced a couple of minutes before the contest begins. Best of luck to everyone!

P.S: Perhaps at the end of the round, you can guess who made which problems (answer: I wrote ABE, minimario wrote CD).

P.P.S: moooooooomooooomomomoooomoomooooooooooooo!

UPD1 : Score-distribution: 500-1000-1500-2000-2500

UPD2: Editorial


Congratulations to the winners:

1) kut_ksr1994

2) balakrishnan

3) r_clover

4) HamidReza_H

5) waItz7I9

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By lewin, 2 weeks ago, In English,

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!

Interested in the work on Wunder Fund?

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

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


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 :-(

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By komendart, history, 3 weeks ago, translation, In English,


Tomorrow, on 23rd of January at 18:35 MSK Codeforces Round #340 (Div. 2) will take place. It's my first round, hope you enjoy the problems.

Thanks to GlebsHP for his help in preparing the problems, Delinur for translations of statements and MikeMirzayanov for Codeforces and Polygon.

Good luck!

UPD Scoring 500-1000-1250-1750-2750

UPD Editorial

UPD Congrats to winners!

Div. 2

  1. AReesha

  2. Miyukine

  3. KefaaLove

  4. zhaoxinyi

  5. thatday

Div. 1

  1. anta

  2. doreamon

  3. uwi

  4. Um_nik

  5. I_love_Tanya_Romanova

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By fivt, 4 weeks ago, translation, In English,

Warning! The dates of the Winter Computer Camp have shifted one day ahead!

From 25 February to 5 March 2016, the Moscow Insitute for Physics and Technology will host the seventh Winter Computer Camp 2016 (WCC-2016) in the city of Dolgoprudny. Students of upper grades are welcome to participate.

The program of the camp includes::

  • Daily studying contests: preparation to the finals of the Open Olympiad, finals of national programming Olympiads.

  • Olympiads in programming and mathematics.

  • Lectures by workers of base organizations of FIHT about actual tasks in the IT Industry.

  • Lectures by professional scientists on combinatorial mathematics.

  • Sports and intellectual games.

How to get to the school:

  1. Fill in the registration form.
  2. Participate in the online selection rounds for the camp. Pay attention that the selection is conducted thoroughly in compliance with the results of the selection rounds.

Online selection rounds*:

  • 27.12.2015 15:00 (UTC+03) — first round,

  • 17.01.2016 15:00 (UTC+03) — second round,

  • 24.01.2016 15:00 (UTC+03) — third round,

  • 07.02.2016 10:00 (UTC+03) — fourth round

**the dates and time of the rounds can change, follow the information on [our website].(

Cost of participation:

  • Free participation is guaranteed to the winners and prizers of the final stage of the All-Russian Olympiad for School Students (or CIS Olympiads) in Informatics and Mathematics.

  • 9900 for winners and awardees of the ALl-Russian Team Olympiad for School Students in Programming and the Open Olympiad for School Students in Programming.

  • 15900 rubles for participants of the final stage of national Olympiads for school students in informatics and mathematics

  • 28900 rubles for other participants.

For any occuring questions, leave messages on the organizing committee email:

The head of programming committee of Winter Computer Camp 2016 is Endagorion.

The Winter Computer Camp is traditionally unique for its line-up of participants: Dolgoprudny hosts large numbers of capable students who already have achievements in All-Russian and National Olympiads of different countries. Preparation of contests is performed by young teachers, professors and students — prize-winners of All-Russian Olympiads for School Students and ACM ICPC student tournaments. Therefore, participation in the WCC-2016 serves as a "final rehearsal" before the Finals of the Open Olympiad and the All-Russian Olympiad in Informatics.

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