February 20, 2017

In Blog News

How to make your Tic Tac Toe game unbeatable by using the minimax algorithm

I struggled for hours scrolling through tutorials, watching videos, and banging my head on the desk trying to build an unbeatable Tic Tac Toe game with a reliable Artificial Intelligence. So if you are going through a similar journey, I would like to introduce you to the Minimax algorithm.

Like a professional chess player, this algorithm sees a few steps ahead and puts itself in the shoes of its opponent. It keeps playing ahead until it reaches a terminal arrangement of the board (terminal state) resulting in a tie, a win, or a loss. Once in a terminal state, the AI will assign an arbitrary positive score (+10) for a win, a negative score (-10) for a loss, or a neutral score (0) for a tie.

At the same time, the algorithm evaluates the moves that lead to a terminal state based on the players’ turn. It will choose the move with maximum score when it is the AI’s turn and choose the move with the minimum score when it is the human player’s turn. Using this strategy, Minimax avoids losing to the human player.

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Special thanks to Tuba Yilmaz, Rick McGavin, and Javid Askerov for reviewing this article.