n = 3

s$=""
for i = 1 to n
    s$=s$;i
next

res$=permutation$("", s$)

Function permutation$(pre$, post$)
    lgth = Len(post$)
    If lgth < 2 Then
        print pre$;post$
    Else
        For i = 1 To lgth
            tmp$=permutation$(pre$+Mid$(post$,i,1),Left$(post$,i-1)+Right$(post$,lgth-i))
        Next i
    End If
End Function