VBA List all possible combination of variable number of items (number of nested loops as variable) - vba

Question

gentleman! I am having trouble with figuring out a way to define the number of elements as variable when listing all possible combinations. I have a hard coded example of this where number of elements = 3
'Declare variables
Dim a as long
Dim b as Long
Dim C as Long
Dim ElementsArray as variant
'Array
ElementsArray = array("1400","1900","2400")
'Loop through combinations
for a = lbound(ElementsArray) to ubound(ElementsArray)
for B= lbound(ElementsArray) to ubound(ElementsArray)
for c = lbound(ElementsArray) to ubound(ElementsArray)
debug.print(ElementsArray(a) & " - " & ElementsArray(b) & " - " & ElementsArray(c))
next c
next b
next a
But What I am looking for is a code in which perhaps the number of nested For loops is a variable or some other ways to permutate through all possible combinations. Please help solve this problem.

Answer 1

Here is an example of a recursive implementation. Just be warned that you shouldn't make your array too large as you will get n to the power of n solutions - for 4 elements, that's 256, for 5 elements 3'125, for 6 you get 46'656 and for 7 already 823'543 - don't complain if the program takes a long time to execute. And of course you need a way to do something with every permutation.
Option Explicit
Sub test()
Dim ElementsArray As Variant
ElementsArray = Array("1400", "1900", "2400")
ReDim SolutionArray(LBound(ElementsArray) To UBound(ElementsArray))
recursion ElementsArray, SolutionArray, LBound(ElementsArray)
End Sub
Sub recursion(elements, solution, level As Long)
Dim i As Long
For i = LBound(elements) To UBound(elements)
solution(level) = elements(i)
If level = UBound(elements) Then
Debug.Print Join(solution, " - ")
Else
recursion elements, solution, level + 1
End If
Next i
End Sub
Update: This is the result:
Update
Still not sure if I understand. The following code will create a list of n-Tupel out of an array of values.
In the example (test), we have an array of 4 values and set n to 3 (defined as constant).
Sub test()
Const n = 3
Dim ElementsArray As Variant
ElementsArray = Array("1400", "1900", "2400", "9999")
ReDim SolutionArray(0 To n - 1)
recursion ElementsArray, SolutionArray, LBound(ElementsArray)
End Sub
Sub recursion(elements, solution, level As Long)
Dim i As Long
For i = LBound(elements) To UBound(elements)
solution(level) = elements(i)
If level = UBound(solution) Then
Debug.Print Join(solution, " - ")
Else
recursion elements, solution, level + 1
End If
Next i
End Sub