International Olympiad in Informatics

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The logo of the International Olympiad in Informatics InternationalOlympiadInInformatics.png
The logo of the International Olympiad in Informatics

The International Olympiad in Informatics (IOI) is an annual competitive programming competition and one of the International Science Olympiads for secondary school students. The first IOI was held in 1989 in Pravetz, Bulgaria.

Contents

Each country sends a team of up to four students, plus one team leader, one deputy leader, and guests. Students in each country are selected for their country's team through national computing contests. Students at the IOI compete on an individual basis. There is no official team ranking.

The contest consists of two days of solving six complicated algorithmic tasks by writing computer programs in C++. [1] [2] All task materials are published on each year's contest website soon after the competition ends.

Competition structure and participation

The competition room at the IOI 2006 IOI 2006 competition room.png
The competition room at the IOI 2006
IOI 2006 bronze medal (front).jpg
Front
IOI 2006 bronze medal (back).jpg
Back
A bronze medal from IOI 2006 in Mexico
In front of the competition room at the IOI 2007 IOI Zagreb 1.JPG
In front of the competition room at the IOI 2007

On each of the two competition days, the competitors are typically given three problems which they have to solve in five hours. Each student works on their own to solve the problems with no outside help, specifically no communication with other contestants, books, web access, etc. Contestants are typically allowed to bring non-programmable wired keyboards and mice. [3] Usually to solve a task the contestant has to write a computer program (in C++) and submit it before the five-hour competition time ends. The program is graded based on secret test data. Since 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 (a.k.a. interactive problems). Another type of problem has the inputs publicly available, 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. Pascal has been removed as an available programming language as of 2019. [4] :11

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. Starting from 2012, IOI has been using the Contest Management System (CMS) for developing and monitoring the contest. [5]

The scores from the two competition days and all problems are summed up separately for each contestant. Medals are awarded 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).

Prior to IOI 2010, students who did not receive medals did not have their scores published, 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.

Analysis of female performance shows 77.9% of women obtain no medal, while 49.2% of men obtain no medal. "The average female participation was 4.4% in 1989–1994 and 2.2% in 1996–2014." It also suggests much higher participation of women on the national level, claiming sometimes double-digit percentages in total participation on the first stage. [6] President of the IOI (2011-2014), 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] The European Girls’ Olympiad in Informatics (EGOI), which was first held in 2021 was started with the goal to increscent female participants at IOI and other Informatics Olympiads. [7]

In IOI 2017 held in Iran, due to not being able to participate in Iran, the Israeli students participated in an offsite competition organized by IOI in Russia. [4] :11 Due to visa issues, the full USA team was unable to attend, although one contestant Zhezheng Luo [8] was able to attend by traveling with the Chinese team [9] and winning gold medal and 3rd place in standings. [10]

In IOI 2019 held in Azerbaijan, the Armenia team did not participate due to the dispute between the two countries, despite the guarantees provided [11] and official invitation letter sent by the host Azerbaijan.

Due to the COVID-19 pandemic, both the IOI 2020 and IOI 2021, originally scheduled to be hosted by Singapore, were held as online contests. The IOI 2022, hosted by Indonesia, was held as a hybrid event, with around 25% of the contestants participating online. [12]

In response to the invasion of Ukraine, students from Russia and Belarus can only participate as individuals under the IOI flag but not as national delegations starting from IOI 2022, and they would only participate online for IOI 2022, but they may return on-site from IOI 2023 onwards. [13]

In response to the conflict and humanitarian crisis in Gaza, students from Israel can only participate as individuals under the IOI flag but not as a national delegation from IOI 2025 onwards. Over two thirds of the delegations voted in favour of the sanction in the IOI General Assembly This corresponds to the proportion of members of the assembly coming from Arab-Muslim countries (including Iran). [14]

Members

Former members

Summary

NumberYearDatesHost countryHost cityResultsWebsite
11989May 16–19 Flag of Bulgaria (1971-1990).svg Bulgaria Pravetz [15]
21990July 15–21 Flag of the Byelorussian Soviet Socialist Republic (1951-1991).svg Belarus, Soviet Union Minsk [16]
31991May 19–25 Flag of Greece.svg Greece Athens [17]
41992July 11–21 Flag of Germany.svg Germany Bonn [18]
51993October 16–25 Flag of Argentina.svg Argentina Mendoza [19] [20]
61994July 3–10 Flag of Sweden.svg Sweden Haninge [21] [22]
71995June 26 – July 3 Flag of the Netherlands.svg Netherlands Eindhoven [23]
81996July 25 – August 2 Flag of Hungary.svg Hungary Veszprém [24]
91997November 30 – December 7 Flag of South Africa.svg South Africa Cape Town [25]
101998September 5–12 Flag of Portugal (official).svg Portugal Setúbal [26]
111999October 9–16 Flag of Turkey.svg Turkey Antalya-Belek [27]
122000September 23–30 Flag of the People's Republic of China.svg China Beijing [28]
132001July 14–21 Flag of Finland.svg Finland Tampere [29]
142002August 18–25 Flag of South Korea.svg Korea Rep. Yong-In [30]
152003August 16–23 Flag of the United States.svg United States Kenosha, Wisconsin [31]
162004September 11–18 Flag of Greece.svg Greece Athens [32]
172005August 18–25 Flag of Poland.svg Poland Nowy Sącz [33] [34]
182006August 13–20 Flag of Mexico.svg Mexico Mérida, Yucatán [35]
192007August 15–22 Flag of Croatia.svg Croatia Zagreb [36] [37]
202008August 16–23 Flag of Egypt.svg Egypt Cairo [38]
212009August 8–15 Flag of Bulgaria.svg Bulgaria Plovdiv [39] [40]
222010August 14–21 Flag of Canada (Pantone).svg Canada Waterloo, Ontario [41] [42]
232011July 22–29 Flag of Thailand.svg Thailand Pattaya [43] [44]
242012September 23–30 Flag of Italy.svg Italy Sirmione and Montichiari [45] [46]
252013July 6–13 Flag of Australia (converted).svg Australia Brisbane [47] [48]
262014July 13–20 Flag of the Republic of China.svg Taiwan Taipei [49] [50]
272015July 26 – August 2 Flag of Kazakhstan.svg Kazakhstan Almaty [51] [52]
282016August 12–19 Flag of Russia.svg Russia Kazan [53] [54]
292017July 28 – August 4 Flag of Iran.svg Iran Tehran [55] [56]
302018September 1–8 Flag of Japan.svg Japan Tsukuba [57] [58]
312019August 4–11 Flag of Azerbaijan.svg Azerbaijan Baku [59] [60]
322020September 13–19 a Flag of Singapore.svg Singapore online [61] [62]
332021June 19–25 Flag of Singapore.svg Singapore online [63] [64]
342022August 7–15 Flag of Indonesia.svg Indonesia Yogyakarta [65] [66]
352023August 28 – September 4 Flag of Hungary.svg Hungary Szeged [67] [68]
362024September 1–8 Flag of Egypt.svg Egypt Alexandria [69] [70]
372025July 27 – August 3 Flag of Bolivia.svg Bolivia Sucre [71] [72]
382026August 9–16 Flag of Uzbekistan.svg Uzbekistan Tashkent [73]
392027September 12–19 Flag of Germany.svg Germany Potsdam [74]
402028 Flag of Japan.svg Japan
412029 Flag of Bulgaria.svg Bulgaria

All-time medal table

As of 2025
RankNationGoldSilverBronzeTotal
1Flag of the People's Republic of China.svg  China  (CHN)1062812146
2Flag of the United States (23px).png  United States  (USA)694117127
3Flag of Russia.svg  Russia  (RUS)684012120
4Flag of South Korea.svg  South Korea  (KOR)535028131
5Flag of Poland.svg  Poland  (POL)455436135
6Flag of Romania.svg  Romania  (ROU)386037135
7Flag of Japan.svg  Japan  (JPN)38331081
8Flag of Iran.svg  Iran  (IRN)336925127
9Flag of Bulgaria.svg  Bulgaria  (BGR)295745131
10Flag of the Republic of China.svg  Taiwan  (TWN)266430120
Totals (10 entries)5054962521,253

Multiple IOI winners

The following is a list of the top performers in the history of the IOI. [75] 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.

NameTeamYears
Gennady Korotkevich BelarusG(II) 2012GP(I) 2011G(I) 2010G(I) 2009G 2008G 2007S 2006
Hristo VenevBulgariaG 2016G 2015G 2014G 2013S 2012
Rain JiangUnited StatesG 2025G 2024G 2023G 2021S 2022
Zixiang ZhouCanadaG 2022G 2021G 2020G(III) 2019S 2018
Filip WolskiPolandG(I) 2006G 2005G 2004G 2003
Rareș Darius BuhaiRomaniaG 2015G 2014G 2013G 2012
Yuta TakayaJapanG(I) 2017G 2016G 2015G 2014
Rumen HristovBulgariaG 2012G 2011G(II) 2010S 2009S 2008
Andrzej Gąsienica-SamekPolandG 1999G 1998G 1997S 1996
Eduard BatmendijnSlovakiaG 2015G 2013G 2012S 2014
Martin PettaiEstoniaG 2002G 2001G 2000S 1999
Nikoloz BirkadzeGeorgiaG 2020G 2019G 2018S 2017
Patrick PavićCroatiaG 2022G 2021G 2020S 2019
Ryan BaiCanadaG 2025G 2024G 2023S 2022
Daiki KodamaJapanG 2023G 2022G 2021
Daniel WeberIsraelG 2024G 2023G 2022
Jarosław KwiecieńPolandG 2016G 2015G 2014
John Pardon United StatesG 2007G 2006G 2005
Marcin AndrychowiczPolandG 2008G 2007G 2006
Martin MarešCzech RepublicG 1995G 1994GP(I) 1993
Masataka YonedaJapanG 2020G 2019GU 2018
Neal WuUnited StatesG 2010G 2009G 2008
Scott Wu United StatesGP(I) 2014G 2013G 2012
Shogo MuraiJapanG 2012G 2011G 2010
Vladimir MartianovRussiaG 1999GP(I) 1998G(I) 1997
Vladimir RomanovRussiaG 2019G 2018G 2017

Feeder competitions

Most participating countries use feeder competitions to select their team. They are usually referred to as National Olympiad in Informatics and is the course of selection of the country's top team or persons to participate in the IOI. A number of these are listed below:

Notes

1. ^a IOI 2020 virtual closing ceremony was held on September 23, 2020.

See also

References

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  2. "Contest Rules". IOI 2024 Egypt. Retrieved 2024-10-15.
  3. "Competition Equipment". IOI 2024 Egypt. Arab Academy. Retrieved 29 July 2024.
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  5. "IOI 2010 Waterloo". IOI 2010 Waterloo. University of Waterloo. Retrieved 29 July 2024.
  6. Maggiolo, Stefano (2015). "An Update on the Female Presence at the IOI" (PDF). Olympiads in Informatics. 9, 127–137 (2015). London, U.K.: ioinformatics.org: 127–137. doi: 10.15388/ioi.2015.10 . Retrieved 13 July 2017.
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  9. Simões, Gabriel (31 July 2017). "IOI 2017, first round - Codeforces". Codeforces. Retrieved 4 August 2017. There is really only one USA contestant on site, it looks like he came with the Chinese team (straight from China).
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