The Fastest Permutation Code Permutating Numbers in VB NET - vb.net

Question

There is a famous and the fastest permutation code without any "function" for VB .Net to permutate numbers just in several rows, that I can't remember unfortunately.
Is there anyone know this code? Or know like this?
Some part of the code is here:
UPDATE: I FOUND IT. ALL THE WORKING CODES HERE:
Dim L(4) As Byte
Dim I As Byte
Dim K As Byte
Dim J As Byte
Dim RESULTS As String
Dim UB, UBm1 As Integer
L = {1, 2, 3, 4, 5}
UB = L.GetUpperBound(0)
UBm1 = UB - 1
Do
I = UBm1
Do While I > 0 And L(I) >= L(I + 1)
I -= 1
Loop
K = L(I)
J = UB
Do While J > 0 And L(J) <= K
J -= 1
Loop
RESULTS = L(0) & "," & L(1) & "," & L(2) & "," & L(3) & "," & L(4)
L(I) = L(J)
L(J) = K
Array.Reverse(L, I + 1, UB - I)
Loop While J

Answer 1

It seems like you're looking for this ...
http://www.cut-the-knot.org/do_you_know/AllPerm.shtml
(2. Lexicographic order and finding the next permutation)
... ?
In case you are, the starting values for I and J are incorrect (they should be 4 and 5 instead of 3 and 4 respectively).
(I know the example uses swap, but that can be replaced with a single colon-delimited line.)
Dim L(4) As Byte
L = {1, 2, 3, 4, 5}
Dim K as Byte
For N as integer = 1 to 120 'No. of permutations: 5!
Dim I As Byte = 4, J as Byte = 5
While L(I - 1) >= L(I)
I -= 1
End While
While L(J - 1) <= L(I - 1)
J -= 1
End While
K = L(I - 1) : L(I - 1) = L(J - 1) : L(J - 1) = K
I += 1 : J = 5
While I < J
K = L(I - 1) : L(I - 1) = L(J - 1) : L(J - 1) = K
I += 1 : J -= 1
End While
Dim RESULT as String = L(0) & "," & L(1) & "," & L(2) & "," & L(3) & "," & L(4)
'Export / print RESULT as you like, e.g. Console.WriteLine or something
Next

Answer 2

For obtaining a set of permutations of a natural number (recommended less than 10 though it can be bigger than that), this VBA Excel sub-routine is very fast and short. I believe it can be easy to convert it to VB.NET. Have a look.
Const P = 5 'Recommended Max P = 9
Dim m As Long, PArray(1 To 1000, 1 To P) 'Recommended Max 9! = 362880
Public Sub PermutationNaturalNumber()
Dim Q(1 To P) As Long
For m = 1 To P: Q(m) = m: Next: m = 0
PermutationGenerator P, Q
Range("A1").Resize(UBound(PArray), P) = PArray: End
End Sub
Sub PermutationGenerator(n As Long, Q() As Long)
Dim i As Long, j As Long, k As Long
If n > 1 Then
For i = 1 To n - 1
PermutationGenerator n - 1, Q
If n Mod 2 = 1 Then j = 1 Else j = i
k = Q(j): Q(j) = Q(n): Q(n) = k
Next
PermutationGenerator n - 1, Q
Else
m = m + 1: For i = 1 To P: PArray(m, i) = Q(i): Next
End If
End Sub
P can be any natural number, in this case {1, 2, 3, 4, 5}. Make sure you change the upper bound of PArray with P! meaning (P*(P-1)*(P-2)*...*1).