Australian Community Informatics Olympiad - Archives

What is this place?

The ACIO was started by two high school students who wanted to make their own informatics olympiad problems. There is no fixed difficulty level for these contests, however they do tend to get harder as the year progresses. There are also a few guest-made contests, namely, the April Fools contest and the Variety Round.

How do I navigate this page?

Pick a year in the navigation bar at the top, and explore all the problems for that year. Typically, both the problem statement and test data for the problem are included, as well as links to at least one (if not several) online judges that host the problem.

Can I use these problems in my contests/lectures/videos?

Sure! If you use these problems for a contest, you may want to confirm with contestants that they have not seen these problems before.
Test data downloads will usually be available under the contest pages.

What are the difficulty levels?

The difficulty level of a contest is a very rough guide of how difficult the problems generally are in the contest. The levels range from 0 to 5:

  1. Focused on implementation with minimal problem solving required.
  2. AIO Q3/Q4 level. Normally only involves a simple algorithm, but no special knowledge required.
  3. AIO Q5/AIIO Q1 level. May involve standard dynamic programming/data structures/algorithms, such as queues, Dijkstra and binary search.
  4. AIIO Q3 level. May involve combining several more advanced techniques compared to the previous level, such as segment trees, sweeplines and divide and conquer optimisations.
  5. Selection Exam Q3/IOI Q2 level. Typically involves numerous observations and techniques to arrive at a solution. An extensive knowledge of the properties and structure of DP, DS and GT is recommended.
  6. Anything considered harder than the previous level.