private Node DoAlphaBeta(bool isMin, Board board, int depth, double alpha = 0, double beta = 1)
{
Node MinMax = new Node()
{
eval = isMin ? 1 : 0
};
if (depth == 0)
{
return(new Node()
{
move = null, eval = board.Evaluate(color)
});
}
List <Point> playerPieces = board.GetAllPiecesPositions(isMin ? Board.OppositeColor(color) : color);
foreach (Point piecePos in playerPieces)
{
foreach (Point move in board.BoardTab[piecePos.x, piecePos.y].GetValidMoves(board, piecePos))
{
Point[] tempMove = new Point[2] {
piecePos, move
};
board.Execute(tempMove);
Node result = DoAlphaBeta(!isMin, board, depth - 1, alpha, beta);
board.UndoMove(1);
if ((isMin && result.eval <= MinMax.eval) || (!isMin && result.eval >= MinMax.eval))
{
MinMax.eval = result.eval;
MinMax.move = tempMove;
}
if (isMin)
{
beta = Math.Min(result.eval, beta);
}
else
{
alpha = Math.Max(result.eval, alpha);
}
if (beta <= alpha)
{
return(MinMax);
}
}
}
return(MinMax);
}
public override Point[] Decide(Board board)
{
Point[] playerChoice = new Point[2];
List <Point> possibilites = board.GetAllPiecesPositions(color);
int choice;
List <Point> aviableMoves;
do
{
choice = random.Next() % possibilites.Count;
aviableMoves = board.BoardTab[possibilites[choice].x, possibilites[choice].y].GetValidMoves(board, possibilites[choice]);
} while (aviableMoves.Count == 0);
playerChoice[0] = possibilites[choice];
choice = random.Next() % aviableMoves.Count;
playerChoice[1] = aviableMoves[choice];
return(playerChoice);
}