Unity 2018 Artificial Intelligence Cookbook - Second Edition

How to do it...

We will add a new function to the BoardAI class as follows:

1. Create the Negamax function:

public static float Negamax( 
        Board board, 
        int maxDepth, 
        int currentDepth, 
        ref Move bestMove) 
{ 
    // next steps here    
}

2. Validate the base case:

if (board.IsGameOver() || currentDepth == maxDepth) 
    return board.Evaluate(); 

3. Set the initial values:

bestMove = null; 
float bestScore = Mathf.NegativeInfinity; 

4. Loop through all the available moves and return the best score:

foreach (Move m in board.GetMoves()) 
{ 
    // next steps here 
} 
return bestScore; 

5. Create a new game state from the current move:

Board b = board.MakeMove(m); 
float recursedScore; 
Move currentMove = null; 

6. Start the recursion:

recursedScore = Negamax(b, maxDepth, currentDepth ...