private StandardRules(StandardRules existing, IReadOnlyBoxPuzzle puzzle)
{
_puzzle = puzzle;
_unsetRowValues = existing._unsetRowValues.AsSpan().ToArray();
_unsetColValues = existing._unsetColValues.AsSpan().ToArray();
_unsetBoxValues = existing._unsetBoxValues.AsSpan().ToArray();
}
private StandardRules(StandardRules existing, IReadOnlyPuzzle?puzzle)
{
_boxSize = existing._boxSize;
_unsetRowValues = existing._unsetRowValues?.AsSpan().ToArray();
_unsetColValues = existing._unsetColValues?.AsSpan().ToArray();
_unsetBoxValues = existing._unsetBoxValues?.AsSpan().ToArray();
_puzzle = puzzle;
}