public static ulong NextMask(this IGenerator rnd, FreeCells cells)
{
var index = cells[rnd.Next(cells.Count)];
ulong mask = rnd.NextCell() << (index * 4);
return(mask);
}
public Board FillEmptySpot(IGenerator rnd)
{
var freeCells = FreeCells.FromBoard(this);
if (freeCells.Any())
{
var bits = Bits | rnd.NextMask(freeCells);
return(new Board(bits, Score));
}
else
{
return(Empty);
}
}