private BestMove minimax(int depth, Player player, int alpha, int beta)
{
BestMove currentMove;
List <BoardSpace> spaces = generateMoves();
spaces.Shuffle();
int score;
string bestPosition = null;
if (spaces.Count == 0 || depth == 0)
{
score = evaluate();
return(new BestMove(score, bestPosition));
}
else
{
foreach (BoardSpace space in spaces)
{
space.owner = BoardState.GetOwner(player.Token);
if (player.Token == currentPlayer.Token)
{
currentMove = minimax(depth - 1, opponentPlayer, alpha, beta);
score = currentMove.Score;
if (score > alpha)
{
alpha = score;
bestPosition = space.position;
}
}
else
{
currentMove = minimax(depth - 1, currentPlayer, alpha, beta);
score = currentMove.Score;
if (score < beta)
{
beta = score;
bestPosition = space.position;
}
}
space.owner = Owner.Empty;
if (alpha >= beta)
{
break;
}
}
}
return(new BestMove((player.Token == currentPlayer.Token)?alpha:beta, bestPosition));
}
public int evaluate()
{
int score = 0;
Owner currentPlayerOwner = BoardState.GetOwner(currentPlayer.token);
Owner opponentPlayerOwner = BoardState.GetOwner(opponentPlayer.token);
score += EvaluateWin(currentBoard.win1, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win2, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win3, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win4, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win5, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win6, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win7, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win8, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win9, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win10, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win11, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win12, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win13, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win14, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win15, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win16, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win17, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win18, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win19, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win20, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win21, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win22, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win23, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win24, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win25, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win26, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win27, currentPlayerOwner, opponentPlayerOwner);
score += EvaluateWin(currentBoard.win28, currentPlayerOwner, opponentPlayerOwner);
return(score);
}
