Module Module1 
'donne toutes les permutations sans doublons d'une chaine de caractres

'le temps traitement et la mmoire exigs dependent de la longueur de la chaine 

Private perms() As String

'chaine de caractres
Public Function GetPerms(ByVal chaine As String) As String() 
  Dim l As Long

  l = factorial(chaine.Length)
  ReDim perms(CInt(l - 1)) 
  permutation(chaine)

' perms = EraseDuplicateString()
  Return perms 
End Function

Private Function rotateright(ByVal str As String) As String

'rotation du string vers la droite le premier caractre passe la seconde place et ainsi de suite la dernier caractre passe la premiere place 
Dim strret As String = String.Empty 
str.ToCharArray()

strret = str(str.Count - 1)
For iter As Integer = 0 To str.Count - 2 
strret = String.Concat(strret, str(iter))
Next

Return strret 
End Function
Private Function EraseDuplicateString() As String() 
'retire les doublons de chaines du tableau perms

perms = perms.Distinct.ToArray
Return perms 
End Function

Private Function factorial(ByVal n As Integer) As Integer

Dim fact As Integer

fact = 1
For iter = 1 To n 
fact = fact * iter

Next
Return fact 
End Function
Private Sub permutation(ByVal str As String) 
' on ajoute le premier string dans le tableau perms

' rotation du mot vers la droite et ajoute au tableau perms

' on refait l'opration longueur du string -1

' on recommence avec tout les strings de perms mais chaque mot commence un caratre 

' droite 

'ex bnok 

' le mot = bnok

' aprs 3 rotation on a kbno okbn nokb 

' on reprend la sous chaine nok de bnok

'aprs 2 rotations kno okn

Dim iter As Integer

Dim strsub As String

Dim startpos As Integer

Dim count As Integer

Dim origstrlen As Integer

Dim elements As Integer

count = 0

perms(count) = str
For iter = 0 To str.Length - 2 
'rotation vers la droite 

str = rotateright(str)

count += 1

'ajouter la chaine au tableau

perms(count) = str

Next

startpos = 1

origstrlen = str.Length - 1
For group = origstrlen To 2 Step -1 
elements = count
For iter = 0 To elements 
strsub = perms(iter).Substring(startpos, group)
For iter2 = 0 To strsub.Length - 2 
'rototion de sous chaine 

strsub = rotateright(strsub)

str = perms(iter).Substring(0, startpos) & strsub

count += 1

perms(count) = str

Next

Next

startpos += 1

Next
End Sub 
End Module