static bool AddPermutation <T>(T[] items, PermutationKey n, int[] p, int oldi, Func <T[], bool> process)
{
if (p.Length == n.NumItemsInPermutation)
{
return(process(p.Select(i => items[i]).ToArray()));
}
else
{
int lowerLimit = n.CombinationsOnly ? oldi : 0;
bool cont = true;
for (int i = lowerLimit; i < n.NumItemsTotal && cont; i++)
{
if (n.AllowDuplicates || !p.Contains(i))
{
cont = AddPermutation(items, n, p.Concat(new[] { i }).ToArray(), i, process);
}
}
}
return(true);
}
public static void Get <T>(T[] items, int numItemsInPermutation, bool allowDuplicates, bool combinationsOnly, Func <T[], bool> process)
{
var permutationKey = new PermutationKey(allowDuplicates, combinationsOnly, items.Length, numItemsInPermutation);
AddPermutation(items, permutationKey, new int[] { }, 0, process);
}