IOI 2019 took place in Azerbaijan, from August 4-11, 2019. More info is available on the official website.
Just finished IOI 2019 in Azerbaijan
The 15th International Olympiad in Informatics was held in Kenosha, Wisconsin, USA in 2003. There were two competition days, with 3 tasks given to the competitors on each day. You can see the tasks and test cases below.
Guess Which Cow
Seeing the Boundary
Note that the grading model changed at IOI'94 and beyond.
Before IOI 1994, a human evaluator would sit behind the competitor's computer and do the testing manually (enter test data through the keyboard, check the output on the screen). Starting from IOI 1994, an automatic grading process is used, with test input defined in files.