Online Judge

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.

A programming competition generally involves the host presenting a set of logical or mathematical problems, also known as puzzles, to the contestants (who can vary in number from tens or even hundreds 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, memory usage, program size, etc.)

History

One of the oldest contests known is the International Collegiate Programming Contest (ICPC) which originated in the 1970s, and has grown to include 88 countries in its 2011 edition.

From 1990 to 1994, Owen Astrachan, Vivek Khera and David Kotz ran one of the first distributed, internet-based programming contests inspired by the ICPC.

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.

Overview

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, algorithmic game theory, computational geometry, string analysis and data structures. Problems related to constraint programming and 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.

Notable competitions

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.

Short-term

* International Collegiate Programming Contest (ICPC) – one of the oldest competitions, for students of universities in groups of 3 persons each
* International Olympiad in Informatics (IOI) – one of the oldest competitions, for secondary school students
* 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 three 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
* Gridwars – four competitions held between 2003 and 2004.
* 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.
* Topcoder Open (TCO) – Algorithm competition held since 2001 by Topcoder

LeetCode Contests
- Weekly and Biweekly contests, 1.5 hours to solve 4 problems.

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 requires onsite participation. A special exception to this is IEEEXtreme, which is a yearly 24-hour virtual programming competition. The top performers at IOI and 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.

Long-term

* HackerRank Week of Code
* ICFP Programming Contest – annual 3-day competition held since 1998 by the International Conference on Functional Programming
* Topcoder Marathon Matches
* Codechef Long Challenges - held every month - lasts up to 10 days

Artificial intelligence and machine learning

* Kaggle – data science and machine learning competitions.
* CodeCup – board game AI competition held annually since 2003. Game rules get published in September and the final tournament is held in January.Lasse Hakulinen
Survey on Informatics Competitions: Developing Tasks
– Olympiads in Informatics, 2011, Vol. 5, 12–25.
* 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.
* CodinGame – hosts seasonal bot programming competitions.

Contests focusing on open source technologies

*List may be incomplete

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. There are several organizations who host programming competitions on a regular basis. These include:

Benefits and criticism

Participation in programming contests may increase student enthusiasm for computer science studies. The skills acquired in ICPC-like programming contests also improve career prospects, as they help to pass the "technical interviews", which often require candidates to solve complex programming and algorithmic problems on the spot.

There has also been criticism of competitive programming, particularly from professional software developers. One critical point is that many fast-paced programming contests teach competitors bad programming habits and code style (like unnecessary use of macros, lack of OOP abstraction and comments, use of short variable names, etc.). Also, by offering only small algorithmic puzzles with relatively short solutions, programming contests like ICPC and IOI don't necessarily teach good software engineering skills and practices, as real software projects typically have many thousands of lines of code and are developed by large teams over long periods of time. Peter Norvig stated that based on the available data, being a winner of programming contests correlated negatively with a programmer's performance at their job at Google (even though contest winners had higher chances of getting hired). Norvig later stated that this correlation was observed on a small data set, but that it could not be confirmed after examining a larger data set

Yet another sentiment is that rather than "wasting" their time on excessive competing by solving problems with known solutions, high-profile programmers should rather invest their time in solving real-world problems.

Literature

* Halim, S., Halim, F. (2013). ''Competitive Programming 3: The New Lower Bound of Programming Contests''. Lulu.
* Laaksonen, A. (2017). ''Guide to Competitive Programming'' (Undergraduate Topics in Computer Science). Cham: Springer International Publishing.

See also

* Computer science competitions
* Code golf
* Hackathon

References

{{Reflist, refs=https://www.atlantis-press.com/proceedings/icaicte-13/8933

External links

;Open-source project for running contests
Contest Management System
Open-source tool in Python to run and manage a programming contest on a server IOI 2012 and IOI 2013.

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Computer science competitions