Data commit

Task/Permutations/VBA/permutations.vba

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+Public Sub Permute(n As Integer, Optional printem As Boolean = True)
+'Generate, count and print (if printem is not false) all permutations of first n integers
+
+Dim P() As Integer
+Dim t As Integer, i As Integer, j As Integer, k As Integer
+Dim count As Long
+Dim Last As Boolean
+
+If n <= 1 Then
+
+  Debug.Print "Please give a number greater than 1"
+  Exit Sub
+
+End If
+
+'Initialize
+ReDim P(n)
+
+For i = 1 To n
+  P(i) = i
+Next
+
+count = 0
+Last = False
+
+Do While Not Last
+   'print?
+   If printem Then
+
+      For t = 1 To n
+        Debug.Print P(t);
+      Next
+
+      Debug.Print
+
+   End If
+
+count = count + 1
+
+Last = True
+i = n - 1
+
+   Do While i > 0
+
+     If P(i) < P(i + 1) Then
+
+       Last = False
+       Exit Do
+
+     End If
+
+     i = i - 1
+   Loop
+
+  j = i + 1
+  k = n
+
+  While j < k
+    ' Swap p(j) and p(k)
+    t = P(j)
+    P(j) = P(k)
+    P(k) = t
+    j = j + 1
+    k = k - 1
+  Wend
+
+  j = n
+
+  While P(j) > P(i)
+    j = j - 1
+  Wend
+
+  j = j + 1
+  'Swap p(i) and p(j)
+  t = P(i)
+  P(i) = P(j)
+  P(j) = t
+Loop 'While not last
+
+Debug.Print "Number of permutations: "; count
+
+End Sub