Competitive programming is a mind sport usually held over the Internet or a local network, involving participants trying to program according to provided specifications. Contestants are referred to as sport programmers. Competitive programming is recognized and supported by several multinational software and Internet companies, such as Google and Facebook. There are several organizations who host programming competitions on a regular basis.
A programming competition generally involves the host presenting a set of logical or mathematical problems to the contestants (who can vary in number from tens to several thousands), and contestants are required to write computer programs capable of solving each problem. Judging is based mostly upon number of problems solved and time spent for writing successful solutions, but may also include other factors (quality of output produced, execution time, program size, etc.)
One of the oldest contests known is ICPC which originated in the 1970s, and has grown to include 88 countries in its 2011 edition. Interest in competitive programming has grown extensively since 2000, and is strongly connected to the growth of the Internet, which facilitates holding international contests online, eliminating geographical problems.
The aim of competitive programming is to write source code of computer programs which are able to solve given problems. A vast majority of problems appearing in programming contests are mathematical or logical in nature. Typical such tasks belong to one of the following categories: combinatorics, number theory, graph theory, geometry, string analysis and data structures. Problems related to artificial intelligence are also popular in certain competitions.
Irrespective of the problem category, the process of solving a problem can be divided into two broad steps: constructing an efficient algorithm, and implementing the algorithm in a suitable programming language (the set of programming languages allowed varies from contest to contest). These are the two most commonly tested skills in programming competitions.
In most contests, the judging is done automatically by host machines, commonly known as judges. Every solution submitted by a contestant is run on the judge against a set of (usually secret) test cases. Normally, contest problems have an all-or-none marking system, meaning that a solution is "Accepted" only if it produces satisfactory results on all test cases run by the judge, and rejected otherwise. However, some contest problems may allow for partial scoring, depending on the number of test cases passed, the quality of the results, or some other specified criteria. Some other contests only require that the contestant submit the output corresponding to given input data, in which case the judge only has to analyze the submitted output data.
Online judges are online environments in which testing takes place. Online judges have ranklists showing users with the biggest number of accepted solutions and/or shortest execution time for a particular problem.
There are two types of competition formats: short-term and long-term. Each round of short-term competition lasts from 1 to 5 hours. Long-term competitions can last from a few days to a few months.
- International Collegiate Programming Contest (ICPC) - one of the oldest competitions, for students of universities in groups of 3 persons each
- American Computer Science League (ACSL) - computer science competition with written and programming portions, for middle/high school students
- CodeChef - competition held from 2009, there are two short contests held every month and an annual competition called CodeChef SnackDown
- Codeforces Round - typically two hour contest, held every week
- Facebook Hacker Cup - competition held from 2011, provided and sponsored by Facebook
- HackerRank - multiple competitions
- Google Code Jam - competition held from 2003, provided and sponsored by Google
- IEEEXtreme Programming Competition - annual competition for IEEE Student Members held since 2006 by IEEE
- IOI - one of the oldest competitions, for secondary school students
- National Olympiad in Informatics, China - competition held in China since 1984
- Topcoder Open (TCO) - Algorithm - competition held since 2001 by Topcoder
In most of the above competitions, since the number of contestants is quite large, competitions are usually organized in several rounds. They usually require online participation in all rounds except the last, which require onsite participation. A special exception to this is IEEEXtreme, which is a yearly 24-hour virtual programming competition. The top performers at IOI and ACM-ICPC receive gold, silver and bronze medals while in the other contests, cash prizes are awarded to the top finishers. Also hitting the top places in the score tables of such competitions may attract interest of recruiters from software and Internet companies.
- HackerRank Week of Code
- ICFP Programming Contest – annual 3-day competition held since 1998 by the International Conference on Functional Programming
- Topcoder Marathon Matches
Artificial intelligence and machine learning
- Kaggle – machine learning competitions.
- CodeCup – AI board game competition held annually since 2003. Game rules get published in September and the final tournament is held in January.
- Google AI Challenge – bi-annual competitions for students that ran 2009 to 2011
- Halite – An AI programming challenge sponsored by Two Sigma, Cornell Tech, and Google
- Russian AI Cup open artificial intelligence programming contest
Online contest and training resources
The programming community around the world has created and maintained several internet-resources dedicated to competitive programming. They offer standalone contests with or without minor prizes. Also the past archives of problems are a popular resource for training in competitive programming. These include:
|CodeChef||Maintained by Directi, it hosts a 10-day-long contest and a couple of short contests every month (one IOI styled and other ACM ICPC styled), and provides a contest hosting platform to educational institutions for free. The top two winners of the long contest win cash prizes while the top 10 global get a tee-shirt.||www|
|CodeCup||Annual international AI board game programming competition organized by the Dutch Olympiad in Informatics since 2003.||codecup|
|Codeforces||Russian resource, maintained by ITMO University, which mostly provides frequent (up to two per week) short contests. Special features: ability to check correctness of other contestants' solutions during "hacking phase", virtual contests, trainings etc.||codeforces|
|CodinGame||Puzzles (increasing difficulty), code golf. Hosts regular online competitions (AI сhallenges, optimization problems)||www|
|HackerEarth||Bangalore, India based company providing online contest like environment aiming at providing recruitment assessment solutions.||www|
|HackerRank||HackerRank offers programming problems in different domains of Computer Science. It also hosts annual Codesprints which help connect the coders and Silicon Valley startups.||hackerrank|
|Project Euler||Large collection of computational math problems (i.e. not directly related to programming but often requiring programming skills for solving).||projecteuler|
|Topcoder||US resource and company, which organizes contests and also provides industrial problems as a kind of free-lance job; it offers dozens of short contests and several long ("marathons") every year. Specific feature - participants have a chance to check correctness of other contestants' solutions after coding phase and before final automatic testing (so called "challenge phase").||www|
|UVa Online Judge||Contains over 4,500 problems for practising. Hosts regular online competitions.||uva|
- "Google Code Jam". google.com. Retrieved 2016-02-20.
- "TCO12 Sponsor: Google - TCO 12". topcoder.com. Archived from the original on February 16, 2012.
- "Facebook Hacker Cup". Facebook. Retrieved 2016-02-20.
- Programming Challenges (Skiena & Revilla) ISBN 0387001638, ISBN 978-0387001630
- "CodeChef Monthly Contests".
- "Programmers from all over the world compete at CodeChef SnackDown - ExchangeMedia".
- "Codeforces contests". Retrieved 2018-10-12.
- "Programming problems and Competitions :: HackerRank". HackerRank. Retrieved 2016-02-20.
- "Programming problems and Competitions :: HackerRank". HackerRank. Retrieved 2016-02-20.
- "CodeCup". www.codecup.nl.
- Lasse Hakulinen. Survey on Informatics Competitions: Developing Tasks – Olympiads in Informatics, 2011, Vol. 5, 12–25.
- Wevers, Lesley (2014). "Monte-Carlo Tree Search for Poly-Y" (PDF). University of Twente. Archived from the original (PDF) on 13 April 2017. Retrieved 16 September 2018.
- "Halite Artificial Intelligence Programming Challenge". www.halite.io.
- "Two Sigma Announces Public Launch of Halite". tech.cornell.edu.
- "Halite helps students and developers compete to build better AI on Google Cloud Platform".
- Open-source project for running contests