public Move GetBestMove(char[] board, int boardSize, int CurrentPlayer, int alpha, int beta, GameLogic logic)
{
Move BestMove = null;
int iPossibleMoves = board.Count(b => b == '-');
//Start at a random square, so that if two or more moves
//are of equal rank, one of them will be chosen at random.
Random rand = new Random();
int i = rand.Next(boardSize);
int j = rand.Next(boardSize);
while (iPossibleMoves > 0)
{
//Loop through board.aiBoard to find next available move
do
{
if (i < boardSize - 1)
{
i++;
}
else if (j < boardSize - 1)
{
i = 0; j++;
}
else
{
i = 0; j = 0;
}
} while (board[FromMatrixToIndex(i,j)] != '-');
Move NewMove = new Move(i, j);
iPossibleMoves--;
//Make Move
char[] NewBoard = (new string(board)).ToCharArray();
NewBoard[FromMatrixToIndex(NewMove.iRow, NewMove.iCol)] = 'O';
var result = logic.GetResult(NewBoard);
if (result == GameResult.NotFinished)
{
Move tempMove = GetBestMove(NewBoard, 3, -CurrentPlayer, alpha, beta, logic);
NewMove.iRank = tempMove.iRank;
}
else
{
//Assign a rank
if (result == GameResult.NotFinished)
NewMove.iRank = 0;
else
{
if (result == GameResult.WonByO)
NewMove.iRank = -1;
else
{
if (result == GameResult.WonByX)
NewMove.iRank = 1;
}
}
}
//Is NewMove the best move encountered at this level so far?
if (BestMove == null ||
(CurrentPlayer == 1 && NewMove.iRank < BestMove.iRank) ||
(CurrentPlayer == -1 && NewMove.iRank > BestMove.iRank))
{
BestMove = NewMove;
}
//Update alpha and beta, if necessary.
if (CurrentPlayer == 1 && BestMove.iRank < beta)
beta = BestMove.iRank;
if (CurrentPlayer == -1 && BestMove.iRank > alpha)
alpha = BestMove.iRank;
//Check for pruning condition.
if (alpha > beta)
{
//prune this branch
iPossibleMoves = 0;
}
}
return BestMove;
}
protected void Click_Command(object sender, CommandEventArgs e)
{
if (ViewState["Board"] == null)
{
ViewState["Board"] = "---------";
}
var board = ViewState["Board"].ToString().ToCharArray();
var index = int.Parse(e.CommandArgument.ToString());
if (board[index] != '-')
{
this.Result.Text = "Invalid move - try again !";
return;
}
board[index] = 'X';
ViewState["Board"] = new string(board);
var logic = new GameLogic();
var resultX = logic.GetResult(board);
if (resultX == GameResult.WonByX)
{
this.Result.Text = "Incredible ! You win ! ";
this.RestartGame();
return;
}
else if (resultX == GameResult.Draw)
{
this.Result.Text = "Draw .. what a surprise .. ";
this.RestartGame();
return;
}
var ai = new TicTacToeAI();
for (int i = 0; i < board.Length; i++)
{
if (board[i] == '-')
{
board[i] = 'O';
break;
}
}
ViewState["Board"] = new string(board);
var resultY = logic.GetResult(board);
if (resultY == GameResult.WonByO)
{
this.Result.Text = "Damn ! You loose ! ";
this.RestartGame();
return;
}
else if (resultY == GameResult.Draw)
{
this.Result.Text = "Draw .. what a surprise .. ";
this.RestartGame();
return;
}
}