Option Explicit
Dim vAllItems As Variant
Dim Buffer() As String
Dim BufferPtr As Long
Dim Results As Worksheet
Sub ListPermutations()
Dim Rng As Range
Dim PopSize As Integer
Dim SetSize As Integer
Dim Which As String
Dim N As Double
Const BufferSize As Long = 4096
Set Rng = Selection.Columns(1).Cells
If Rng.Cells.Count = 1 Then
Set Rng = Range(Rng, Rng.End(xlDown))
End If
PopSize = Rng.Cells.Count - 2
If PopSize < 2 Then GoTo DataError
SetSize = Rng.Cells(2).Value
If SetSize > PopSize Then GoTo DataError
Which = UCase$(Rng.Cells(1).Value)
Select Case Which
Case "C"
N = Application.WorksheetFunction.Combin(PopSize, SetSize)
Case "P"
N = Application.WorksheetFunction.Permut(PopSize, SetSize)
Case Else
GoTo DataError
End Select
If N > Cells.Count Then GoTo DataError
Application.ScreenUpdating = False
Set Results = Worksheets.Add
vAllItems = Rng.Offset(2, 0).Resize(PopSize).Value
ReDim Buffer(1 To BufferSize) As String
BufferPtr = 0
If Which = "C" Then
AddCombination PopSize, SetSize
Else
AddPermutation PopSize, SetSize
End If
vAllItems = 0
Application.ScreenUpdating = True
Exit Sub
DataError:
If N = 0 Then
Which = "Enter your data in a vertical range of at least 4 cells. " _
& String$(2, 10) _
& "Top cell must contain the letter C or P, 2nd cell is the number" _
& "of items in a subset, the cells below are the values from which" _
& "the subset is to be chosen."
Else
Which = "This requires " & Format$(N, "#,##0") & _
" cells, more than are available on the worksheet!"
End If
MsgBox Which, vbOKOnly, "DATA ERROR"
Exit Sub
End Sub
Private Sub AddPermutation(Optional PopSize As Integer = 0, _
Optional SetSize As Integer = 0, _
Optional NextMember As Integer = 0)
Static iPopSize As Integer
Static iSetSize As Integer
Static SetMembers() As Integer
Static Used() As Integer
Dim i As Integer
If PopSize <> 0 Then
iPopSize = PopSize
iSetSize = SetSize
ReDim SetMembers(1 To iSetSize) As Integer
ReDim Used(1 To iPopSize) As Integer
NextMember = 1
End If
For i = 1 To iPopSize
If Used(i) = 0 Then
SetMembers(NextMember) = i
If NextMember <> iSetSize Then
Used(i) = True
AddPermutation , , NextMember + 1
Used(i) = False
Else
SavePermutation SetMembers()
End If
End If
Next i
If NextMember = 1 Then
SavePermutation SetMembers(), True
Erase SetMembers
Erase Used
End If
End Sub 'AddPermutation
Private Sub AddCombination(Optional PopSize As Integer = 0, _
Optional SetSize As Integer = 0, _
Optional NextMember As Integer = 0, _
Optional NextItem As Integer = 0)
Static iPopSize As Integer
Static iSetSize As Integer
Static SetMembers() As Integer
Dim i As Integer
If PopSize <> 0 Then
iPopSize = PopSize
iSetSize = SetSize
ReDim SetMembers(1 To iSetSize) As Integer
NextMember = 1
NextItem = 1
End If
For i = NextItem To iPopSize
SetMembers(NextMember) = i
If NextMember <> iSetSize Then
AddCombination , , NextMember + 1, i + 1
Else
SavePermutation SetMembers()
End If
Next i
If NextMember = 1 Then
SavePermutation SetMembers(), True
Erase SetMembers
End If
End Sub 'AddCombination
Private Sub SavePermutation(ItemsChosen() As Integer, _
Optional FlushBuffer As Boolean = False)
Dim i As Integer, sValue As String
Static RowNum As Long, ColNum As Long
If RowNum = 0 Then RowNum = 1
If ColNum = 0 Then ColNum = 1
If FlushBuffer = True Or BufferPtr = UBound(Buffer()) Then
If BufferPtr > 0 Then
If (RowNum + BufferPtr - 1) > Rows.Count Then
RowNum = 1
ColNum = ColNum + 1
If ColNum > 256 Then Exit Sub
End If
Results.Cells(RowNum, ColNum).Resize(BufferPtr, 1).Value _
= Application.WorksheetFunction.Transpose(Buffer())
RowNum = RowNum + BufferPtr
End If
BufferPtr = 0
If FlushBuffer = True Then
Erase Buffer
RowNum = 0
ColNum = 0
Exit Sub
Else
ReDim Buffer(1 To UBound(Buffer))
End If
End If
'construct the next set
For i = 1 To UBound(ItemsChosen)
sValue = sValue & ", " & vAllItems(ItemsChosen(i), 1)
Next i
'and save it in the buffer
BufferPtr = BufferPtr + 1
Buffer(BufferPtr) = Mid$(sValue, 3)
End Sub 'SavePermutation