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.

Day 1:
      Trail Maintenance
      Comparing Code
      Reverse

Day 2:
      Guess Which Cow
      Amazing Robots
      Seeing the Boundary

Other materials:
      Test cases


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.