Codeforces is a website that hosts competitive programming contests. It is maintained by a group of competitive programmers from ITMO University led by Mikhail Mirzayanov. Since 2013, Codeforces claims to surpass Topcoder in terms of active contestants . As of 2018, it has over 600 000 registered users . Codeforces along with other similar websites are used by top sport programmers like Gennady Korotkevich, Petr Mitrichev and Makoto Soejima, but also non-celebrity programmers interested in furthering their careers .
- Short (2-hours) contests, called "Codeforces Rounds", held about once a week
- Educational contests (2-2.5 hours, with 24 hours hacking period), 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 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  or "Microsoft Q# Coding Contest — Summer 2018" provided by Microsoft .
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 2018-12-26 .
|Rating Bounds||Color||Title||Division||Number||Number (by color)|
|≥ 3000||Black & Red||Legendary Grandmaster||1||23(31)||338(594)|
|2600 — 2999||Red||International Grandmaster||1||103(157)|
|2400 — 2599||Red||Grandmaster||1||212(406)|
|2300 — 2399||Orange||International Master||1||143(364)||1234(2492)|
|2100 — 2299||Orange||Master||1||1091(2128)|
|1900 — 2099||Violet||Candidate Master||1/2||1944(5503)||1944(5503)|
|1600 — 1899||Blue||Expert||2||6387(21596)||6387(21596)|
|1400 — 1599||Cyan||Specialist||2/3||13454(51629)||13454(51629)|
|1200 — 1399||Green||Pupil||2/3||19362(60964)||19362(60964)|
Codeforces was created by a group of competitive programmers from Saratov State University led by Mikhail Mirzayanov. It was originally created for those interested in solving tasks and taking part in competitions . 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 is recommended by many universities. 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 .
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. 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.
Result by country
- ACM International Collegiate Programming Contest
- Facebook Hacker Cup
- Google Code Jam
- Online judge
- UVa Online Judge
- "North korean college coders beat Stanford University in a 2016". mic.com.
Codeforces — a Russian competitive coding site with contestants from around the world
- "Codeforces Founder Will Teach Web Development at ITMO". news.ifmo.ru.
- "Codeforces results 2013". codeforces.com.
- "Codeforces results 2017". codeforces.com.
- "The jocks of computer code do it for the job offers". bloomberg.com.
- "Are programming competitions a good use of time?". wordpress.com.
- "Student of CSE Dept. becomes Candidate Master in Codeforces". www.lus.ac.bd.
- Difference between HackerRank, LeetCode, topcoder and Codeforces (Youtube). Event occurs at 1:45.
Difference between HackerRank, LeetCode, topcoder and Codeforces: "Topcoder and Codeforces is a website that's typically used when preparing for actual competitive programming contests"
- "All-Ireland Programming Olympiad Training". aipo.computing.dcu.ie.
- "ACM-ICPC training at FIT CTU". turing.cz (in Czech).
- "The 30-minute guide to rocking your next coding interview". medium.freecodecamp.org.
CodeForces questions are more similar to questions in competitive programming
- "Competitive Programmer's Handbook" (PDF). cses.fi.
At the moment, the most active contest site is Codeforces, which organizes contests about weekly.
- "Algorithms programming competitions". tildeweb.au.dk.
- "Grading Systems for Algorithmic Contests" (PDF). Olympiads in Informatics. 12: 159–166. 2018. doi:10.15388/ioi.2018.13.
- "Lyft 2018". blog.lyft.com.
- "Microsoft Q# Coding Contest". cloudblogs.microsoft.com.
- "Codeforces: Updates in rating and rounds". codeforces.com.
- "Introduction-CS 97SI-Stanford University" (PDF). web.stanford.edu.
- "Introduction,COMP4128 Programming Challenges, School of Computer Science and Engineering, UNSW Australia" (PDF). cse.unsw.edu.au.
- "15-295: Competition Programming and Problem Solving, Fall 2016". cs.cmu.edu.
- "Barcelona Bootcamp". gsnmagazine.com.
- "Companies making ACM-ICPC bootcamp available for everyone". in.harbour.space.