public int Minimax(int depth, int turn, int alpha, int beta, int player) // turn - 1 for max, 2 for min
{
if (beta <= alpha)
{
return(turn == 1 ? int.MaxValue : int.MinValue);
}
var gameResult = GameResult(_b);
switch (gameResult)
{
case 1:
return(int.MaxValue / 2);
case 2:
return(int.MinValue / 2);
case 0:
return(0);
}
if (depth == _maxDepth)
{
return(EvaluateBoard(_b, player));
}
int maxScore = int.MinValue, minScore = int.MaxValue;
for (var j = 0; j <= 6; ++j)
{
var currentScore = 0;
if (!_b.IsLegalMove(j))
{
continue;
}
if (turn == 1)
{
_b.PlaceMove(j, 1);
currentScore = Minimax(depth + 1, 2, alpha, beta, player);
if (depth == 0)
{
if (currentScore > maxScore)
{
_nextMoveLocation = j;
}
if (currentScore == int.MaxValue / 2)
{
_b.UndoMove(j);
break;
}
}
maxScore = Math.Max(currentScore, maxScore);
alpha = Math.Max(currentScore, alpha);
}
else if (turn == 2)
{
_b.PlaceMove(j, 2);
currentScore = Minimax(depth + 1, 1, alpha, beta, player);
minScore = Math.Min(currentScore, minScore);
beta = Math.Min(currentScore, beta);
}
_b.UndoMove(j);
if (currentScore == int.MaxValue || currentScore == int.MinValue)
{
break;
}
}
return(turn == 1 ? maxScore : minScore);
}