AI that plays the game Othello/Reversi against you.
This was my student assignment in the first year of college on the subject called "Algorithms and data structures" by professor Branko Milosavljevic.
As at that time console applications were the only thing I knew how to make, so it doesn't have a cool GUI but steel is pretty fun to play.
It uses minimax algorithm with alfa-beta pruning to find the best move possible. Also because I optimized board storing and heuristic calculation for every position I was able to make it predict up to 7 turns in advanced so good luck trying to beat it.
Regarding the structures used to design the project, I implemented my version of ChainedHashMap to store already calculated board positions (as one of the optimization techniques) and also I implemented BinaryTree used for pruning. Since it was one of the requirements of the project all the calculations are done in less than 3 seconds so you feel like you are playing against a real pro.