Public Sub Quick(a() As Variant, last As Integer)
' quicksort a Variant array (1-based, numbers or strings)
Dim aLess() As Variant
Dim aEq() As Variant
Dim aGreater() As Variant
Dim pivot As Variant
Dim naLess As Integer
Dim naEq As Integer
Dim naGreater As Integer
If last > 1 Then 'choose pivot in the middle of the array pivot = a(Int((last + 1) / 2)) 'construct arrays naLess = 0 naEq = 0 naGreater = 0 For Each el In a() If el > pivot Then naGreater = naGreater + 1 ReDim Preserve aGreater(1 To naGreater) aGreater(naGreater) = el ElseIf el < pivot Then naLess = naLess + 1 ReDim Preserve aLess(1 To naLess) aLess(naLess) = el Else naEq = naEq + 1 ReDim Preserve aEq(1 To naEq) aEq(naEq) = el End If Next 'sort arrays "less" and "greater" Quick aLess(), naLess Quick aGreater(), naGreater 'concatenate P = 1 For i = 1 To naLess a(P) = aLess(i): P = P + 1 Next For i = 1 To naEq a(P) = aEq(i): P = P + 1 Next For i = 1 To naGreater a(P) = aGreater(i): P = P + 1 Next
End If
End Sub
Public Sub QuicksortTest()
Dim a(1 To 26) As Variant 'populate a with numbers in descending order, then sort For i = 1 To 26: a(i) = 26 - i: Next Quick a(), 26 For i = 1 To 26: Debug.Print a(i);: Next Debug.Print 'now populate a with strings in descending order, then sort For i = 1 To 26: a(i) = Chr$(Asc("z") + 1 - i) & "-stuff": Next Quick a(), 26 For i = 1 To 26: Debug.Print a(i); " ";: Next Debug.Print
End Sub