/// <summary>
/// (x,y) に Mark をおいたときにひっくり返る座標のリストを返す。
/// </summary>
/// <returns>The when put.</returns>
/// <param name="x">The x coordinate.</param>
/// <param name="y">The y coordinate.</param>
/// <param name="mark">Mark.</param>
public List <Pos> ReverseWhenPut(int x, int y, ReversiMark mark)
{
List <Pos> poses = new List <Pos>();
var dx = new int[] { -1, 0, 1, -1, 1, -1, 0, 1 };
var dy = new int[] { -1, -1, -1, 0, 0, 1, 1, 1 };
// 8近傍を探索
for (int i = 0; i < dx.Length; i++)
{
if (!ReversiBoard.IsIn(x + dx [i], y + dy [i]))
{
continue;
}
// 隣が反対の色であることが重要
if ((int)this.At(x + dx [i], y + dy [i]) == -(int)mark)
{
List <Pos> candidates = new List <Pos> ();
bool flag = false; // その方向にひっくり返せるかのフラグ
for (int j = 1; true; j++)
{
var x2 = x + dx [i] * j;
var y2 = y + dy [i] * j;
if (!ReversiBoard.IsIn(x2, y2))
{
break;
}
if ((int)this.At(x2, y2) == -(int)mark)
{
candidates.Add(new Pos(x2, y2));
}
else if (this.At(x2, y2) == mark)
{
flag = true;
break;
}
else
{
break;
}
}
if (flag)
{
poses.AddRange(candidates);
}
}
}
return(poses);
}
/// <summary>
/// (x, y) に mark を置けるならtrueです
/// </summary>
/// <returns><c>true</c> if this instance is puttable at the specified x y mark; otherwise, <c>false</c>.</returns>
/// <param name="x">The x coordinate.</param>
/// <param name="y">The y coordinate.</param>
/// <param name="mark">Mark.</param>
public bool IsPuttableAt(int x, int y, ReversiMark mark)
{
if (!ReversiBoard.IsIn(x, y))
{
return(false);
}
if (this.At(x, y) != ReversiMark.EMPTY)
{
return(false);
}
if (this.ReverseWhenPut(x, y, mark).Count == 0)
{
return(false);
}
return(true);
}
