LotusScript Quicksort Code

Below is an implementation of a quicksort algorithm in LotusScript. Quicksort is a popular sorting algorithm known for its efficiency and simplicity. The basic idea behind quicksort is to divide an array into two sub-arrays and sort these arrays. Subdividing the array to the point that it can’t be separated anymore will allow it a quick sorting process.

Here is the LotusScript code for quicksort I created from one of my old college programming books.  I tried hard to provide all the variables with meaningful names so the code would be easier to understand.

Sub QuickSort(LowerBound As Integer, UpperBound As Integer, ArrayToSort As Variant)  
  Dim PivotValue As Variant
  Dim LeftIndex As Integer
  Dim RightIndex As Integer
      
  If UpperBound > LowerBound Then   'Nothing to sort, exit subroutine
    PivotValue = ArrayToSort(LowerBound)   'Starting point
    RightIndex = UpperBound
    LeftIndex = LowerBound
         
    'Repeat until LeftIndex and RightIndex "meet in the middle"
    While (LeftIndex < RightIndex) 
            
      'Reduce boundaries while data is sorted			
      While (ArrayToSort(LeftIndex) <= PivotValue And LeftIndex < UpperBound)      
        LeftIndex = LeftIndex + 1
      Wend
            
      While (ArrayToSort(RightIndex) > PivotValue)
        RightIndex = RightIndex - 1
      Wend
            
      'Is data between LeftIndex and RightIndex out of order, swap it
      If LeftIndex < RightIndex  Then   
        Call SwapValues(ArrayToSort(LeftIndex), ArrayToSort(RightIndex))
      End If
           
    Wend
         
    Call SwapValues(ArrayToSort(LowerBound), ArrayToSort(RightIndex))
  
    'Recursive call to sort data
    Call QuickSort(LowerBound, RightIndex - 1, ArrayToSort) 

    'Recursive call to sort data
    Call QuickSort((RightIndex + 1), UpperBound, ArrayToSort)
  End If
End Sub

If you would like to test the quicksort code, you may use the following in a LotusScript agent or action.

Dim myArray As Variant
Dim teststr As String
Dim delim As String
teststr = Jan,Feb,Mar,Apr,May,June,July,Aug,Sept,Oct,Nov,Dec"
delim = ","
myArray = Split(teststr, delim)
	
Call QuickSort(myArray, 0, UBound(myArray))

Dim x As integer
For x = 0 To UBound(myArray)
	MsgBox myarray(x)
Next

I would like to hear any recommendations to improve the quicksort code.

Tags: #dominoforever