//NegaAlpha法
private float NegaAlpha(Stone.ColorType color, int depth,
float alpha, float beta)
{
if (depth == 0)
{
return(Evaluator.Evaluate(board, color));
}
var movable = board.GetMovableBitBoard(color);
if (LogicBoard.CountBit(movable) == 0)
{
board.Log();
var eval = -NegaAlpha(Stone.GetReverseColor(color), depth - 1,
-beta, -alpha);
board.Undo();
return(eval);
}
while (movable != 0)
{
ulong next = GetLeastSignificantBit(movable);
board.Log();
board.Reverse(next, color);
var eval = -NegaAlpha(Stone.GetReverseColor(color), depth - 1,
-beta, -alpha);
board.Undo();
if (beta <= eval)
{
return(eval);
}
alpha = Mathf.Max(eval, alpha);
movable ^= next;
}
return(alpha);
}
//合法手の数を取得
private static int CountMovableCells(Stone.ColorType color)
{
var movable = board.GetMovableBitBoard(color);
return(LogicBoard.CountBit(movable));
}