Recursive combinations [please help]

How do I make the code below recursive? I'm trying to create all combination of the array. This gives all combinations where the length is exactly 5. I want it to give all combinatoin where the length is 1 to the ubound of array s. So for a length of 3 there would be 3 nested loops, for length of 8 there would be 8 nested loops and so on.

Ultimately what I want to accomplish is to have an array filled with numbers and find the sum of every possible combination and pick the combination that has a sum that is closet to a target number without going under, but I thought I'd start here first.

VB Code:

Sub CreateCombos()
 
    Dim s(8)
 
    s(1) = "A"
    s(2) = "B"
    s(3) = "C"
    s(4) = "D"
    s(5) = "E"
    s(6) = "F"
    s(7) = "G"
    s(8) = "H"
 
    lLen = 5
 
    For i1 = 1 To (UBound(s) - lLen) + 1
    For i2 = i1 + 1 To (UBound(s) - lLen) + 2
    For i3 = i2 + 1 To (UBound(s) - lLen) + 3
    For i4 = i3 + 1 To (UBound(s) - lLen) + 4
    For i5 = i4 + 1 To (UBound(s) - lLen) + 5
                    
        Debug.Print s(i1) & s(i2) & s(i3) & s(i4) & s(i5)
    
    Next i5
    Next i4
    Next i3
    Next i2
    Next i1
 
End Sub

Any help? :)

By definition, for a procedure to be recursive, it must call itself.

VB Code:

Option Explicit
 
Private Sub CreateCombos()
  Dim s(1 To 4) As String
  Dim MyCombo As String
  Dim MaxLen As Long
  
  s(1) = "A"
  s(2) = "B"
  s(3) = "C"
  s(4) = "D"
  
  Call ComboRecursion(s, MyCombo, 1, 3)
End Sub
 
Private Sub ComboRecursion(s() As String, MyCombo As String, ByVal ThisLen As Long, MaxLen As Long)
  Dim i As Long
  
  For i = LBound(s) To UBound(s)
    MyCombo = MyCombo & s(i)
    If ThisLen < MaxLen Then
      Call ComboRecursion(s, MyCombo, ThisLen + 1, 3)
    Else
      Debug.Print MyCombo
    End If
    MyCombo = Left$(MyCombo, ThisLen - 1)
  Next i
End Sub
 
Private Sub Command1_Click()
  Call CreateCombos
End Sub

This code obviously doesn't do what you want, but it should give you an idea about how to approach this.

I still don't get it. I understand recursion, but I just can't seem to apply it to my own code. Any help? :)

OK, any way to do this without recursion? I don't care. I just need a way to handle this where lLen could be anything so there could be an infinite number of for...next loops. I'm not getting anything to work. Please help. :)

G'Day WH, how are ya.

Wouldn't the math be (in the example at least)
8x7x6x5x4x3x2x1 (being a range from 1-8)

So that something simple like A,B,C (an Array of 3 elements) yould yeild:

ABC
ACB
BAC
BCA
CAB
CBA

For this you have 3x2x1 = 6, hence 6 results (above) for A,B,C.


Is that theory correct (if so I have seen it posted here before)?

Quote:

---

Originally Posted by Bruce Fox

G'Day WH, how are ya.

Wouldn't the math be (in the example at least)
8x7x6x5x4x3x2x1 (being a range from 1-8)

So that something simple like A,B,C (an Array of 3 elements) yould yeild:

ABC
ACB
BAC
BCA
CAB
CBA

Is that theory correct (if so I have seen it posted here before)?

---

No, no, no. The idea is to get combinations, not permutations (if I'm using those words right). ABC is the same as ACB as far as I'm concerned. I have an array of numbers. I need to find the best combination of those numbers so that the some of the combination gets closest to a target value. The sum of A+B+C would be the same as the sum of A+C+B. So I need exclusive combinations. And I need every combination or every length. The array might have 8 numbers, but the best combination might consist of only two of those numbers, or only one, or all 8.

I think I'm getting close with the code below, but I'm not sure how to work in the array.

VB Code:

Sub DooDah()
 
    For x = 1 To 3
        Combo "", 0, x, 1, 4
    Next x
 
End Sub
 
Sub Combo(sPrefix, lDepth, lLen, lMin, lMax)
 
    For i = lMin To lMax
      If lDepth = (lLen - 1) Then
        Debug.Print sPrefix & i
      Else
        Combo sPrefix & i, lDepth + 1, lLen, i + 1, lMax + 1
      End If
    Next i
 
End Sub

Bwwwahhhhahhhahhhhaa!!! :D

I've at least managed to do what I asked for in the original post. Now I just need to work in the array.

VB Code:

Sub DooDah()
 
    For x = 1 To 5
        Combo "", 0, x, 1, 5
    Next x
 
End Sub
 
Sub Combo(sPrefix, lDepth, lLen, lMin, lMax)
 
    For i = lMin To lMax
      If lDepth = (lLen - 1) Then
        Debug.Print sPrefix & Chr$(i + 64)
      Else
        Combo sPrefix & Chr$(i + 64), lDepth + 1, lLen, i + 1, lMax
      End If
    Next i
 
End Sub

Could you now pass each Array element from an ireration within the DooDah() Sub (similar to the For/Next (x - being the Array Index))?