private IEnumerable <Tuple <Cube, Cube> > GetPairs(Rubik rubik)
{
foreach (Cube edge in rubik.Cubes.Where(c => c.IsEdge && Rubik.GetTargetFlags(c).HasFlag(CubeFlag.MiddleLayer)))
{
Cube corner = rubik.Cubes.First(c => c.IsCorner && (rubik.GetTargetFlags(c) & ~CubeFlag.BottomLayer) == (rubik.GetTargetFlags(edge) & ~CubeFlag.MiddleLayer));
if (!rubik.IsCorrect(corner) || !rubik.IsCorrect(edge))
{
yield return(new Tuple <Cube, Cube>(edge, corner));
}
}
}
