Competitive programming

Competitive programming is a mind sport usually held over the internet or a local network, involving participants trying to program according to provided specifications. Competitive programming is recognized and supported by several multinational software and internet companies, such as Google, Facebook and IBM. As of January 2012 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.)

History

Since programming itself is a very recently developed branch of engineering, competitive programming is a very young sport. One of the oldest contests known is ACM 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.

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, 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.

Notable Competitions

• IOI - one of the oldest competitions, for secondary school students
• ACM ICPC - one of the oldest competitions, for students of universities in groups of 3 persons each;
• Google Code Jam - competition held from 2003, provided and sponsored by Google;
• Facebook Hacker Cup - competition held from 2011, provided and sponsored by Facebook;
• TopCoder Open - competition held since 2004 by TopCoder.

In most of the above competitions, since number of contestants are quite large, competitions are usually organized in several rounds. They usually require "online" participation in all rounds except the last, which require "onsite" participation. 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.

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:

• 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").
• SPOJ - Polish online judge system which provides a lot of problems for training, and provides a platform for other organizers to host their programming contests.
• CodeForces - Russian resource, maintained by Saratov State University, which mostly provides frequent (up to two per week) short contests. Special features: ability to check correctness of other contestants' solutions during "coding phase", virtual contests, trainings etc.
• Codechef - Maintained by Directi, it hosts a 10 day long contest and another short contest every month, and provides a contest platform.

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 [IOI2012].