View source for Codeforces

{{Short description|Competitive programming website}}
{{Infobox website
| name = Codeforces
| logo = Codeforces's new logo.png
| type = [[Competitive programming]]
| language = English, Russian
| country_of_origin = [[Russia]]
| owner = Mikhail Mirzayanov
| author = Mikhail Mirzayanov
| url = {{url|https://codeforces.com/}}
| users = 600,000
| launch_date = {{start date|2009|4|10}}
| current_status = Active
}}

'''Codeforces''' ({{lang-ru|Кодефорсес}}) is a website that hosts [[competitive programming]] contests.<ref>{{Cite web|url=https://mic.com/articles/186412/north-korean-college-coders-beat-stanford-university-in-a-2016-competition-heres-why-that-matters#.9baJjoyF5|archive-url=https://web.archive.org/web/20201109024608/https://www.mic.com/articles/186412/north-korean-college-coders-beat-stanford-university-in-a-2016-competition-heres-why-that-matters#.9baJjoyF5|url-status=dead|archive-date=November 9, 2020|title=North korean college coders beat Stanford University in a 2016|website=mic.com|quote=Codeforces — a Russian competitive coding site with contestants from around the world}}</ref> It is maintained by a group of competitive programmers from [[ITMO University]] led by Mikhail Mirzayanov.<ref name="news_itmo">{{Cite web|url=http://news.ifmo.ru/en/education/official/news/7861/|title=Codeforces Founder Will Teach Web Development at ITMO|website=news.ifmo.ru|date=20 September 2018 }}</ref> Since 2013, Codeforces claims to surpass [[Topcoder]] in terms of active contestants.<ref>{{Cite web|url=http://codeforces.com/blog/entry/10148|title=Codeforces results 2013|website=codeforces.com}}</ref> As of 2019, it has over 600,000 registered users.<ref>{{Cite web|url=https://codeforces.com/blog/entry/56831|title=Codeforces results 2017|website=codeforces.com}}</ref> Codeforces along with other similar websites are used by some sport programmers, like [[Gennady Korotkevich]], [[Petr Mitrichev]], Benjamin Qi and [[Makoto Soejima]], and by other programmers interested in furthering their careers.<ref>{{Cite news|url=https://www.bloomberg.com/news/features/2015-09-25/the-jocks-of-computer-code-do-it-for-the-job-offers|title=The jocks of computer code do it for the job offers|newspaper=Bloomberg|date=25 September 2015 }}</ref><ref>{{Cite web|url=https://luckytoilet.wordpress.com/tag/codeforces/|title=Are programming competitions a good use of time?|website=wordpress.com|date=23 December 2016 }}</ref><ref>{{Cite web|url=http://www.lus.ac.bd/news/student-of-cse-dept-becomes-candidate-master-in-codeforces/|title=Student of CSE Dept. becomes Candidate Master in Codeforces|website=www.lus.ac.bd|date=26 April 2018 }}</ref>

== Overview ==

The Codeforces platform is typically used when preparing for competitive programming contests<ref>{{cite AV media |title=Difference between HackerRank, LeetCode, Topcoder and Codeforces |medium=Youtube |language=English |url=https://www.youtube.com/watch?v=J267bz_G7xE&t=1m45s |time=1:45 |quote=Difference between HackerRank, LeetCode, Topcoder and Codeforces: "Topcoder and Codeforces is a website that's typically used when preparing for actual competitive programming contests" }}</ref><ref>{{Cite web|url=http://aipo.computing.dcu.ie/training|title=All-Ireland Programming Olympiad Training|website=aipo.computing.dcu.ie|access-date=2018-10-26|archive-date=2019-12-18|archive-url=https://web.archive.org/web/20191218032907/http://aipo.computing.dcu.ie/training|url-status=dead}}</ref><ref>{{Cite web|url=https://turing.cz/tom/acm.html|title=ACM-ICPC training at FIT CTU|website=turing.cz|language=Czech}}</ref><ref>{{Cite web|url=https://medium.freecodecamp.org/coding-interviews-for-dummies-5e048933b82b|title=The 30-minute guide to rocking your next coding interview|website=medium.freecodecamp.org|date=16 February 2022 |quote=CodeForces questions are more similar to questions in competitive programming}}</ref> and it offers the following features:

* Short (2-hours) contests, called "Codeforces Rounds", held about once a week<ref>{{Cite book |last=Laaksonen |first=Antti |url=https://cses.fi/book/book.pdf |title=Competitive Programmer's Handbook |year=2018 |page=16 |quote="At the moment, the most active contest site is Codeforces, which organizes contests about weekly."}}</ref><ref>{{Cite web|url=http://tildeweb.au.dk/au121/code/|title=Algorithms programming competitions|website=tildeweb.au.dk}}</ref>
* Educational contests (2-2.5 hours, with 12 hours (24 hours before Round 45) hacking period),<ref>{{cite journal
| last2      = Zsakó
| first2     = László
| date       = 2018
| title      = Grading Systems for Algorithmic Contests
| url        = https://ioinformatics.org/journal/v12_2018_159_166.pdf
| journal    = Olympiads in Informatics
| volume     = 18
| issue      = 1
| pages      = 159–166
| doi        = 10.15388/ioi.2018.13
| access-date = 
| last1 = Erdősné Németh
| first1 = Ágnes
}}</ref> 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.{{fact|date=April 2023}}
[[File:Codeforces logo.svg|thumb|Codeforces non-official vectorized main logo.(Without sponsors)]]

==Rating system==
Contestants are rated by a system similar to [[Elo rating system]]. There are usually no prizes for winners, though several 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]]<ref>{{Cite web|url=https://blog.lyft.com/level-5-challenge-terms/|title=Lyft 2018|website=blog.lyft.com}}</ref> or "Microsoft [[Q Sharp|Q#]] Coding Contest — Summer 2018" provided by [[Microsoft]].<ref>{{Cite web|url=https://cloudblogs.microsoft.com/quantum/2018/06/27/challenge-your-skills-in-the-microsoft-q-coding-contest-summer-2018/|title=Microsoft Q# Coding Contest|website=cloudblogs.microsoft.com|date=27 June 2018 }}</ref>

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. There is also a Div. 4, which is for users rated below 1400.<ref>{{Cite web|url=https://codeforces.com/blog/entry/77028|title=About Division 4 Rounds|website=codeforces.com}}</ref>

{| class="wikitable"
!Rating range
!Title
!Division
|-
|≥ 4000
| '''{{font color|red|T}}{{font color|black|ourist}}'''
|1
|-
|3000 — 3999
| '''{{font color|black|L}}{{font color|red|egendary Grandmaster}}'''
|1
|-
|2600 — 2999
| '''{{font color|red|International Grandmaster}}'''
|1
|-
|2400 — 2599
| '''{{font color|red|Grandmaster}}'''
|1
|-
|2300 — 2399
| '''{{font color|orange|International Master}}'''
|1
|-
|2100 — 2299
| '''{{font color|orange|Master}}'''
|1
|-
|1900 — 2099
| '''{{font color|purple|Candidate Master}}'''
|1/2
|-
|1600 — 1899
| '''{{font color|blue|Expert}}'''
|2
|-
|1400 — 1599
| '''{{font color|#03a89e|Specialist}}'''
|2/3
|-
|1200 — 1399
| '''{{font color|green|Pupil}}'''
|2/3/4
|-
|≤ 1199
| '''{{font color|gray|Newbie}}'''
|2/3/4
|}

== History ==
Codeforces was created by a group of competitive programmers from [[Saratov State University]] led by Mike Mirzayanov. It was originally created for those interested in solving tasks and taking part in competitions.<ref name="news_itmo" /> The first Codeforces Round was held on February 19, 2010 with 175 participants. As of the end of August 2022, over 800 rounds were held, with over 9000 registered competitors per round on average.{{fact|date=April 2023}} Before 2012, Codeforces Rounds were titled "Codeforces Beta Rounds" to indicate that the system was still under development.{{fact|date=April 2023}}

== Academic use ==
Codeforces is recommended by many universities.<ref>{{Cite web|url=https://web.stanford.edu/class/cs97si/01-introduction.pdf|title=Introduction-CS 97SI-Stanford University|website=web.stanford.edu}}</ref><ref>{{Cite web|url=http://www.cse.unsw.edu.au/~cs4128/18s1/lectures/1-introduction.pdf|title=Introduction,COMP4128 Programming Challenges, School of Computer Science and Engineering, UNSW Australia|website=cse.unsw.edu.au}}</ref> 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.<ref>{{Cite web|url=https://contest.cs.cmu.edu/295/f16/|title=15-295: Competition Programming and Problem Solving, Fall 2016|website=cs.cmu.edu}}</ref> At the [[National University of Singapore]], Codeforces rating is also used as an entrance qualifying criterion for registering for a 4-unit course, CS3233 Competitive Programming, as students have to achieve a rating of at least 1559 to be able to register for the course.<ref>{{Cite web|url=https://www.comp.nus.edu.sg/~stevenha/cs3233.html|title=CS3233 - Competitive Programming}}</ref> 

== See also ==<!-- PLEASE RESPECT ALPHABETICAL ORDER -->
* [[CodeChef]]
* [[CodeFights]]
* [[Facebook Hacker Cup]]
* [[Google Code Jam]]
* [[HackerRank]]
* [[International Collegiate Programming Contest]] 
* [[Online judge]]
* [[SPOJ]]
* [[Topcoder]]
* [[UVa Online Judge]]

== References ==
{{reflist}}

== External sources ==
* [https://codeforces.com/ Official website]

[[Category:Programming contests]]
[[Category:ITMO University]]