The International Olympiad in Informatics (IOI) is an annual computer science competition for secondary school students. The first IOI was held in 1989 in Pravetz, Bulgaria.
The contest consists of two days computer programming, solving problems of an algorithmic nature. Students compete on an individual basis, with up to four students competing from each participating country (with around 81 countries in 2004). Students in the national teams are selected through national computing contests, such as the Australian Informatics Olympiad, British Informatics Olympiad, and Bundeswettbewerb Informatik (Germany).
The IOI is one of the most prestigious Computer Science competitions in the world. UNESCO and IFIP are patrons of the International Olympiad in Informatics.
Structure of the competition
On each of the two competition days, the students are typically given four 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++ or Pascal) and submit it before the five hour competition time ends. The program is graded by being run with secret test data. For 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 will for the first time have 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).
Unlike other science olympiads, the IOI regulations specifically prohibit ranking by countries. Although unofficial rankings are circulated within some participating nations, there is therefore no standard. Students who do not receive medals do 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.
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