Codeforces

Codeforces is a competitive programming website^[1]. It was created and is maintained by a group of competitive programmers from Saratov State University led by Mikhail Mirzayanov. Since 2013, Codeforces claims to surpass Topcoder in terms of active contestants ^[2]. As of 2017, it had more than 600 000 registered users ^[3]. Major online judges like Codeforces are used by top sport programmers like Gennady Korotkevich, Petr Mitrichev or Makoto Soejima, but also non-celebrity programmers interested in furthering their careers^[4] ^[5]^[6].

Overview

The Codeforces platform is typically used when preparing for competitive programming contests^[7]^[8]^[9]^[10] and it offers the following features:

Short (2-hours) contests, called "Codeforces Rounds", held about once a week^[11]^[12]
Educational contests (2-2.5 hours, with 24 hours hacking period^[13] ), held 2-3 times per month;
Challenge/hack other contestants' solutions;
Solve problems from previous contests for training purposes;
"Polygon" feature for creating and testing problems;
Social networking through internal public blogs.

Contestants are rated by a system similar to ELO. There are usually no prizes for winners, though 2-3 times a year special contests are held, in which top performing contestants receive T-shirts. Some bigger contests are hosted on Codeforces base, among them "The Lyft Level 5 Challenge 2018", provided by Lyft ^[14] or "Microsoft Q# Coding Contest — Summer 2018" provided by Microsoft ^[15].

Contestants are divided into ranks based on their ratings. Since May 2018, users with ratings between 1900 and 2099 can be rated in both Div. 1 and Div. 2 contests. At the same time, Div. 3 was created for users rated below 1600.The table below was up-to-date on 2018-05-15 ^[16].

Rating Bounds	Color	Title	Division	Number	Number (by color)
≥ 3000	Red	Legendary Grandmaster	1	14	261
2600 — 2999	Red	International Grandmaster	1	90
2400 — 2599	Red	Grandmaster	1	157
2300 — 2399	Orange	International Master	1	134	792
2100 — 2299	Orange	Master	1	658	792
1900 — 2099	Violet	Candidate Master	1/2	2101	2101
1600 — 1899	Blue	Expert	2	5186	5186
1400 — 1599	Cyan	Specialist	2/3	10408	10408
1200 — 1399	Green	Pupil	2/3	15584	15584
≤ 1199	Gray	Newbie	2/3	6250	6250

History

Codeforces was originally created for those interested in solving tasks and taking part in competitions ^[17]. The first Codeforces Round was held on the February 19, 2010 with 175 participants. As of the end of January 2016 over 300 rounds were held, with over 5000 registered competitors per round on average. Before 2012 Codeforces Rounds were titled "Codeforces Beta Rounds" to indicate that the system was still under development.

Use in Academia

Codeforces are recommended by many universities^[18]^[19]^[20]^[21]. According to Daniel Sleator, professor of Computer Science at Carnegie Mellon University, competitive programming is valuable in computer science education because competitors learn to adapt classic algorithms to new problems, thereby improving their understanding of algorithmic concepts. He has used Codeforces problems in his class, 15-295: Competition Programming and Problem Solving ^[22].

Hello Barcelona ACM-ICPC Bootcamp

In February 2017, Codeforces supported the Hello Barcelona ACM-ICPC Bootcamp, a training program for students preparing for the ACM International Collegiate Programming Contest. Codeforces founder and CEO Mike Mirzayanov participated as a coach for the program, which invited 150 university students^[23]. The second Barcelona bootcamp which was held Sept 27 to Oct 5, 2017 had participants from 25 different universities including Georgia Institute of Technology, Technical University of Munich or the ACM-ICPC winners ITMO University^[24].

Rankings

Result by country

Country	Rating
Russia	3058
Poland	2993
China	2991
South Korea	2949
Japan	2910
United States	2817
Belarus	2801
Ukraine	2749
Taiwan	2681
Canada	2636
Romania	2606
Hong Kong	2461
Vietnam	2457
India	2437
Iran	2432
Croatia	2431
Czech Republic	2414
Kazakhstan	2383
Indonesia	2372
Germany	2348