ArrayPermutations()

%REM
		Description: Array permutation function based on the Heap algorithm. Returns all possible configurations 
			of array elements, as a ListOfVariant where each element in the list is one array configuration.
		Created Dec 22, 2020 by Sam Sirry
%END REM
Public Function ArrayPermutations(array As Variant, array_max_idx As Long) As ListOfVariant
	Dim Result As New ListOfVariant
	
	If (array_max_idx = 0) Then
		Call Result.Add(array)
		GoTo Quit
	End If

	Call Result.AssimilateListOfVariant(ArrayPermutations(array, array_max_idx - 1))
	
	Dim i As Long
	For i = 0 To array_max_idx-1
		Dim tmp
		If array_max_idx Mod 2 = 0 Then
			tmp = array(0)
			array(0) = array(array_max_idx)
			array(array_max_idx) = tmp
		Else
			tmp = array(i)
			array(i) = array(array_max_idx)
			array(array_max_idx) = tmp
		End If
		
		Call Result.AssimilateListOfVariant(ArrayPermutations(array, array_max_idx - 1))
	Next
	
Quit:
	Set ArrayPermutations = Result
End Function