The 29th International Olympiad in Informatics was held in Tehran, Iran in 2017. 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:
      Nowruz
      Wiring
      Toy Train

Day 2:
      The Big Prize
      Simurgh
      Ancient Books

Other materials:
      Test cases
      Solutions to all problems
      Practice 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.