International Olympiad in Informatics

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The logo of the International Olympiad in Informatics

The International Olympiad in Informatics (IOI) is an annual competitive programming competition for secondary school students. It is the second largest olympiad, after International Mathematical Olympiad, in terms of number of participating countries (IOI 2014 saw participation of 84 countries). The first IOI was held in 1989 in Pravetz, Bulgaria.

The contest consists of two days of computer programming and problem-solving of algorithmic nature. To deal with problems involving very large amounts of data, it is necessary to have not only programmers, "but also creative coders, who can dream up what it is that the programmers need to tell the computer to do. The hard part isn't the programming, but the mathematics underneath it."[1] Students at the IOI compete on an individual basis, with up to four students competing from each participating country (with 81 countries in 2012). Students in the national teams are selected through national computing contests, such as the Australian Informatics Olympiad, British Informatics Olympiad, Indian Computing Olympiad and Bundeswettbewerb Informatik (Germany).

The International Olympiad in Informatics is one of the most prestigious computer science competitions in the world. UNESCO and IFIP are patrons.

Competition structure and participation[edit]

IOI 2009's banner above the competition room

On each of the two competition days, the students are typically given three problems which they have to solve in five hours. Each student works on his/her own, with only a computer and no other help allowed, specifically no communication with other contestants, books etc. Usually to solve a task the contestant has to write a computer program (in C, C++, Pascal, or Java[2]) and submit it before the five-hour competition time ends. The program is graded by being run with secret test data. From IOI 2010, tasks are divided into subtasks with graduated difficulty, and points are awarded only when all tests for a particular subtask yield correct results, within specific time and memory limits. In some cases, the contestant's program has to interact with a secret computer library, which allows problems where the input is not fixed, but depends on the program's actions – for example in game problems. Another type of problem has known inputs which are publicly available already during the five hours of the contest. For these, the contestants have to submit an output file instead of a program, and it is up to them whether they obtain the output files by writing a program (possibly exploiting special characteristics of the input), or by hand, or by a combination of these means.

IOI 2010 for the first time had a live web scoreboard with real-time provisional results. Submissions will be scored as soon as possible during the contest, and the results posted. Contestants will be aware of their scores, but not others', and may resubmit to improve their scores.

The scores from the two competition days and all problems are summed up separately for each contestant. At the awarding ceremony, contestants are awarded medals depending on their relative total score. The top 50% of the contestants are awarded medals, such that the relative number of gold : silver : bronze : no medal is approximately 1:2:3:6 (thus 1/12 of the contestants get a gold medal).

The competition room at the IOI 2006
A bronze medal from IOI 2006 in Mexico
In front of the competition room at the IOI 2007

Unlike other science olympiads, the IOI regulations specifically prohibit ranking countries. Although unofficial rankings are circulated within some participating nations, there is therefore no standard. Prior to IOI 2010, students who did not receive medals did not have their scores published, making it impossible for a country to be ranked by adding together scores of its competitors unless each wins a medal. From IOI 2010, although the scores of students who did not receive medals are still not available in the official results, they are known from the live web scoreboard. In IOI 2012 the top 3 nations ranked by aggregate score (Russia, China and USA) were subsequently awarded during the closing ceremony.

President of the IOI, Richard Forster, says the competition has difficulty attracting women and that in spite of trying to solve it, "none of us have hit on quite what the problem is, let alone the solution."[1]

List of IOI websites and locations[edit]

Number Year Dates Host country Host city Website Results
1 1989 May 16–19 Bulgaria Bulgaria Pravetz (results)
2 1990 July 15–21 Soviet Union Belarus, Soviet Union Minsk (results)
3 1991 May 19–25 Greece Greece Athens (results)
4 1992 July 11–21 Germany Germany Bonn (results)
5 1993 October 16–25 Argentina Argentina Mendoza (website) (results)
6 1994 July 3–10 Sweden Sweden Haninge (results)
7 1995 June 26 – July 3 Netherlands Netherlands Eindhoven (website) (results)
8 1996 July 25 – August 2 Hungary Hungary Veszprém (website) (results)
9 1997 November 30 – December 7 South Africa South Africa Cape Town (results)
10 1998 September 5–12 Portugal Portugal Setúbal (results)
11 1999 October 9–16 Turkey Turkey Antalya-Belek (website) (results)
12 2000 September 23–30 China China Beijing (results)
13 2001 July 14–21 Finland Finland Tampere (website) (results)
14 2002 August 18–25 South Korea Korea Rep. Yong-In (website) (results)
15 2003 August 16–23 United States USA Kenosha, Wisconsin (website) (results)
16 2004 September 11–18 Greece Greece Athens (website) (results)
17 2005 August 18–25 Poland Poland Nowy Sącz (website) (results)
18 2006 August 13–20 Mexico Mexico Mérida, Yucatán (website) (results)
19 2007 August 15–22 Croatia Croatia Zagreb (website) (results)
20 2008 August 16–23 Egypt Egypt Cairo (website) (results)
21 2009 August 8–15 Bulgaria Bulgaria Plovdiv (website) (results)
22 2010 August 14–21 Canada Canada Waterloo, Ontario (website) (results)
23 2011 July 22–29 Thailand Thailand Pattaya (website) (results)
24 2012 September 23–30 Italy Italy Sirmione and Montichiari (website) (results)
25 2013 July 6–13 Australia Australia Brisbane (website) (results)
26 2014 July 13–20 Taiwan Taiwan Taipei (website) (results)
27 2015 July 26 - August 2 Kazakhstan Kazakhstan Almaty (website)


28 2016 August 12 - 19 Russia Russia Kazan (website) (results)
29 2017 July 28 - August 4 Iran Iran Tehran (website)
30 2018 Japan Japan Tokyo
31 2019 Azerbaijan Azerbaijan Baku (website)
32 2020 Singapore Singapore (website)

Multiple IOI winners[edit]

The following is a list of the top performers in the history of the IOI.[3] The P sign indicates a perfect score, a rare achievement in IOI history. The U sign indicates an unofficial participation, where a contestant participated in a host's second team. Also, first (I), second (II) and third (III) places among gold medalists are indicated where appropriate. This list includes only those countries where the national selection contest allows the same participant to go multiple times to the IOI.

Name Team Years
Gennady Korotkevich Belarus G(II) 2012 GP(I) 2011 G(I) 2010 G(I) 2009 G 2008 G 2007 S 2006
Hristo Venev Bulgaria G 2016 G 2015 G 2014 G 2013 S 2012
Filip Wolski Poland G(I) 2006 G 2005 G 2004 G 2003
Rares-Darius Buhai Romania G 2015 G 2014 G 2013 G 2012
Rumen Hristov Bulgaria G 2012 G 2011 G(II) 2010 S 2009 S 2008
Martin Pettai Estonia G 2002 G 2001 G 2000 S 1999
Andrzej Gąsienica-Samek Poland G 1999 G 1998 G 1997 S 1996
Eduard Batmendijn Slovakia G 2015 G 2013 G 2012 S 2014
Vladimir Martianov Russia G 1999 GP(I) 1998 G(I) 1997
Scott Wu United States GP(I) 2014 G 2013 G 2012
Martin Mareš Czech Republic G 1995 G 1994 G 1993
John Pardon United States G 2007 G 2006 G 2005
Marcin Andrychowicz Poland G 2008 G 2007 G 2006
Neal Wu United States G 2010 G 2009 G 2008
Shogo Murai Japan G 2012 G 2011 G 2010
Jarosław Kwiecień Poland G 2016 G 2015 G 2014
Yuta Takaya Japan G 2016 G 2015 G 2014
Alex Schwendner United States G 2005 G 2003 S 2004 S 2002
Wolfgang Thaller Austria G 1997 G 1996 S 1999 S 1998
Bruce Merry South Africa G 2001 G 2000 S 1999 B 1998 B 1997 B 1996
Goran Žužić Croatia G 2008 G 2007 S 2009 B 2006
Vlad Alexandru Gavrilă Romania G 2013 G 2012 S 2011 B 2010
Victor Bargachev Russia G(I) 1995 G(I) 1994 S 1993
Johnny Ho United States GP(I) 2012 G 2011 S 2013
Eric Price United States GP(I) 2005 GU 2003 S 2004
Mihai Pătraşcu Romania G(II) 2001 G 2000 S 1999
Roman Pastoukhov Russia G 2000 G(II) 1999 S 2001
Piotr Zieliński Poland G 1997 G(III) 1996 S 1995
Fredrik Huss Sweden G 1993 G 1992 S 1991
Miroslav Dudík Slovakia G 1997 G 1996 S 1995
Richard Královič Slovakia G 1999 G 1998 S 1997
Tomasz Czajka Poland (1998, 2000), United Kingdom (1999) G 2000 G 1999 S 1998
Petr Mitrichev Russia G 2002 G 2000 S 2001
Luka Kalinovčić Croatia G 2004 G 2003 S 2002
Rostislav Rumenov Bulgaria G 2007 G 2006 S 2005
Richard McCutchen United States G 2007 G 2005 S 2006
Vladislav Epifanov Russia G 2008 G 2007 S 2009
Cosmin Gheorghe Romania G 2009 G 2008 S 2007
Pasin Manurangsi Thailand G 2011 G 2010 S 2009
Wenyu Cao United States G 2011 G 2010 S 2009

See also[edit]


External links[edit]

Open-source project for running contests: