International Olympiad in Informatics

Template:Short description Template:Primary sources

File: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.

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++.<ref name="Robson">Template:Cite news</ref><ref>Template:Cite web</ref> All task materials are published on each year's contest website soon after the competition ends.

Competition structure and participation

File:IOI 2006 competition room.png

The competition room at the IOI 2006

Template:Multiple image

File: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-programable wired keyboards and mice.<ref>Template:Cite web</ref> 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.<ref name="minutes16">Template:Cite web</ref>^: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.<ref>Template:Cite web</ref>

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.<ref>Template:Cite journal</ref> 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."<ref name="Robson" /> 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.<ref>Template:Cite web</ref>

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.<ref name="minutes16" />^:11 Due to visa issues, the full USA team was unable to attend, although one contestant Zhezheng Luo<ref>Template:Cite web</ref> was able to attend by traveling with the Chinese team<ref>Template:Cite web</ref> and winning gold medal and 3rd place in standings.<ref name="standings2017">Template:Cite web</ref>

In IOI 2019 held in Azerbaijan, the Armenia team did not participate due to the dispute between the two countries, despite the guarantees provided<ref>Template:Cite web</ref> 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.<ref>Template:Cite web</ref>

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.<ref>Template:Cite web</ref>

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.<ref>Template:Cite web</ref>

Template:Clr

Members

Template:Div col

Template:Div col end

Former members

Template:Div col

Template:Div col end

Summary

Number	Year	Dates	Host country	Host city	Results	Website
1	1989	May 16–19	Template:Flagicon Bulgaria	Pravetz	<ref>Template:Cite web</ref>
2	1990	July 15–21	Template:Flagicon Belarus, Soviet Union	Minsk	<ref>Template:Cite web</ref>
3	1991	May 19–25	Template:Flagicon Greece	Athens	<ref>Template:Cite web</ref>
4	1992	July 11–21	Template:Flagicon Germany	Bonn	<ref>Template:Cite web</ref>
5	1993	October 16–25	Template:Flagicon Argentina	Mendoza	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
6	1994	July 3–10	Template:Flagicon Sweden	Haninge	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
7	1995	June 26 – July 3	Template:Flagicon Netherlands	Eindhoven	<ref>Template:Cite web</ref>
8	1996	July 25 – August 2	Template:Flagicon Hungary	Veszprém	<ref>Template:Cite web</ref>
9	1997	November 30 – December 7	Template:Flagicon South Africa	Cape Town	<ref>Template:Cite web</ref>
10	1998	September 5–12	Template:Flagicon Portugal	Setúbal	<ref>Template:Cite web</ref>
11	1999	October 9–16	Template:Flagicon Turkey	Antalya-Belek	<ref>Template:Cite web</ref>
12	2000	September 23–30	Template:Flagicon China	Beijing	<ref>Template:Cite web</ref>
13	2001	July 14–21	Template:Flagicon Finland	Tampere	<ref>Template:Cite web</ref>
14	2002	August 18–25	Template:Flagicon Korea Rep.	Yong-In	<ref>Template:Cite web</ref>
15	2003	August 16–23	Template:Flagicon United States	Kenosha, Wisconsin	<ref>Template:Cite web</ref>
16	2004	September 11–18	Template:Flagicon Greece	Athens	<ref>Template:Cite web</ref>
17	2005	August 18–25	Template:Flagicon Poland	Nowy Sącz	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
18	2006	August 13–20	Template:Flagicon Mexico	Mérida, Yucatán	<ref>Template:Cite web</ref>
19	2007	August 15–22	Template:Flagicon Croatia	Zagreb	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
20	2008	August 16–23	Template:Flagicon Egypt	Cairo	<ref>Template:Cite web</ref>
21	2009	August 8–15	Template:Flagicon Bulgaria	Plovdiv	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
22	2010	August 14–21	Template:Flagicon Canada	Waterloo, Ontario	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
23	2011	July 22–29	Template:Flagicon Thailand	Pattaya	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
24	2012	September 23–30	Template:Flagicon Italy	Sirmione and Montichiari	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
25	2013	July 6–13	Template:Flagicon Australia	Brisbane	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
26	2014	July 13–20	Template:Flagicon Taiwan	Taipei	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
27	2015	July 26 – August 2	Template:Flagicon Kazakhstan	Almaty	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
28	2016	August 12–19	Template:Flagicon Russia	Kazan	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
29	2017	July 28 – August 4	Template:Flagicon Iran	Tehran	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
30	2018	September 1–8	Template:Flagicon Japan	Tsukuba	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
31	2019	August 4–11	Template:Flagicon Azerbaijan	Baku	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
32	2020	September 13–19Template:Ref	Template:Flagicon Singapore	online	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
33	2021	June 19–25	Template:Flagicon Singapore	online	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
34	2022	August 7–15	Template:Flagicon Indonesia	Yogyakarta	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
35	2023	August 28 – September 4	Template:Flagicon Hungary	Szeged	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
36	2024	September 1–8	Template:Flagicon Egypt	Alexandria	<ref>Template:Cite web</ref>	<ref>Template:Cite web</ref>
37	2025	July 27 – August 3	Template:Flagicon Bolivia	Sucre		<ref>Template:Cite web</ref>
38	2026		Template:Flagicon Uzbekistan			<ref>Template:Cite web</ref>
39	2027		Template:Flagicon Germany	Potsdam

All-time medal table

Template:Medals table

Multiple IOI winners

The following is a list of the top performers in the history of the IOI.<ref>Template:Cite web</ref> 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.

Name	Team	Years
Gennady Korotkevich	Belarus	G(II) 2012	G^P(I) 2011	G(I) 2010	G(I) 2009	G 2008	G 2007	S 2006
Bruce Merry	South Africa	G 2001	G 2000	S 1999	B 1998	B 1997	B 1996
Rumen Hristov	Bulgaria	G 2012	G 2011	G(II) 2010	S 2009	S 2008
Hristo Venev	Bulgaria	G 2016	G 2015	G 2014	G 2013	S 2012
Encho Mishinev	Bulgaria	G 2017	G 2014	S 2016	S 2015	S 2013
Egor Lifar	Russia	G 2021	G 2019	S 2020	S 2018	S 2017
Harris Leung	Hong Kong	G 2021	G(III) 2020	S 2019	B 2018	B 2017
Zixiang Zhou	Canada	G 2022	G 2021	G 2020	G(III) 2019	S 2018
Wolfgang Thaller	Austria	G 1997	G 1996	S 1999	S 1998
Andrzej Gąsienica-Samek	Poland	G 1999	G 1998	G 1997	S 1996
Martin Pettai	Estonia	G 2002	G 2001	G 2000	S 1999
Alex Schwendner	United States	G 2005	G 2003	S 2004	S 2002
Filip Wolski	Poland	G(I) 2006	G 2005	G 2004	G 2003
Goran Žužić	Croatia	G 2008	G 2007	S 2009	B 2006
Vlad Alexandru Gavrilă	Romania	G 2013	G 2012	S 2011	B 2010
Eduard Batmendijn	Slovakia	G 2015	G 2013	G 2012	S 2014
Rareș Darius Buhai	Romania	G 2015	G 2014	G 2013	G 2012
Yuta Takaya	Japan	G(I) 2017	G 2016	G 2015	G 2014
Nikoloz Birkadze	Georgia	G 2020	G 2019	G 2018	S 2017
Dorijan Lendvaj	Croatia	G 2022	G 2021	S 2020	B 2019
Patrick Pavić	Croatia	G 2022	G 2021	G 2020	S 2019
Fredrik Huss	Sweden	G^P(I) 1993	G^P(I) 1992	S 1991
Martin Mareš	Czech Republic	G 1995	G 1994	G^P(I) 1993
Vladimir Martianov	Russia	G 1999	G^P(I) 1998	G(I) 1997
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
Scott Wu	United States	G^P(I) 2014	G 2013	G 2012
Jarosław Kwiecień	Poland	G 2016	G 2015	G 2014
Vladimir Romanov	Russia	G 2019	G 2018	G 2017
Masataka Yoneda	Japan	G 2020	G 2019	G^U 2018
Daiki Kodama	Japan	G 2023	G 2022	G 2021