public static bool LegalPath(this Cell[,] board, int x, int y)
{
if (!board.Contains(x, y) || board[x, y] != Cell.Full)
{
return(true);
}
var copy = board.Copy();
FloodFill(copy, x, y, Cell.Full + 1);
return(!copy.Points().Any(s => copy[s.x, s.y] == Cell.Full));
}
public static bool LegalNumbers(this Cell[,] board, int x, int y)
{
if (!board.Contains(x, y))
{
return(true);
}
if (board[x, y] >= 0)
{
var cellNumber = (int)board[x, y];
var countUnknown = 0;
var countFull = 0;
foreach (var(dx, dy) in Cardinals)
{
var scale = 1;
var foundUnknown = false;
while (true)
{
var newX = x + dx * scale;
var newY = y + dy * scale;
if (!board.Contains(newX, newY) || board[newX, newY] == Cell.Empty || board[newX, newY] >= 0)
{
break;
}
if (foundUnknown || board[newX, newY] == Cell.Unknown)
{
foundUnknown = true;
countUnknown++;
}
else if (board[newX, newY] == Cell.Full && ++countFull > cellNumber)
{
return(false);
}
scale++;
}
}
return(countUnknown + countFull >= cellNumber && (cellNumber != 0 || countFull <= 0));
}
foreach (var(dx, dy) in Cardinals)
{
var scale = 1;
while (true)
{
var newX = x + dx * scale;
var newY = y + dy * scale;
if (!board.Contains(newX, newY))
{
break;
}
if (board[newX, newY] >= 0)
{
if (!board.LegalNumbers(newX, newY))
{
return(false);
}
break;
}
scale++;
}
}
return(true);
}
public static bool LegalSquare(this Cell[,] board, int x, int y) => !board.Contains(x, y) || board[x, y] != Cell.Full || !Diagonals.Select(d => (x: x + d.x, y: y + d.y)).Any(s =>
