public static Level GetSubsetLevel(Level level, bool withSokoban, int boxes)
{
// Validate the desired numberes of boxes.
if (boxes > level.Boxes)
{
throw new InvalidOperationException("too many boxes");
}
// Remove all the undesired occupants.
int removeCount = level.Boxes - boxes;
Array2D<Cell> newData = new Array2D<Cell>(level.Data);
int removed = 0;
foreach (Coordinate2D coord in level.InsideCoordinates)
{
// Remove the undesired boxes.
if (removed < removeCount && level.IsBox(coord))
{
newData[coord] &= ~Cell.Box;
removed++;
}
if (!withSokoban)
{
newData[coord] &= ~Cell.Sokoban;
}
}
return new Level(newData);
}
