The 12th International Olympiad in Informatics was held in Beijing, China in 2000. There were two competition days, with 3 tasks given to the competitors on each day. You can see the tasks, test cases and solutions below.

Day 1:
      Palindrome
      Car Parking
      Median Strength

Day 2:
      Walls
      Post Office
      Building with Blocks

Other materials:
      Test cases and some source codes
      Solutions to all problems


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.