[RESOLVED] [2005] Generating a list (again)

[stimbo]

http://www.vbforums.com/showthread.php?t=455508

I posted the above and thought it was working but turned out it wasn't. I've since somehow managed to completely mess it up. Can anyone look at this and suggest a reason? I've added break points but can't figure out where the problem actually exists. The originalList definitely contains 120 items, 20 each of the letters A,B,C, X, Y, Z

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        'Declared outside of subroutine:
        '  Private originalList As New List(Of String)
        ' Private masterList As New List(Of String)

        Dim myRandom As New Random
        Dim RandomIndex As Integer = 0
        Dim tempSelected As String = Nothing 'The item selected to be evaluated:
        Dim same2Letters, same4Category As Boolean
        Dim GroupA_count, GroupB_count As Integer
        Dim previousGroup As String = Nothing

        Do Until masterList.Count = 120

            Do
                'Step 1: Select Random Letter from Original List
                'From 0 to 119: .Count = 120
                RandomIndex = myRandom.Next(0, originalList.Count)
                tempSelected = originalList(RandomIndex)  'Current letter selected

                same2Letters = True        'Reset/set loop conditions
                same4Category = True
                GroupA_count = 0           'Reset category counters
                GroupB_count = 0

                Select Case masterList.Count

                    Case Is <= 1   'Only 0 or 1 item exists: item can be automatically added
                        '  masterList.Add(tempSelected)   see below
                        same2Letters = False
                        same4Category = False
                        Exit Select

                    Case Else
                        'Check previous 2 items in the MasterList: if not the same then:
                        If masterList(masterList.Count - 1) <> _
                        masterList(masterList.Count - 2) Then 'check passed:
                            same2Letters = False   '2 previous items aint the same: good
                        End If

                        'Now check for Category membership:
                        'A,B,C = GroupA;   X,Y,Z = GroupB
                        For i As Integer = masterList.Count - 1 To masterList.Count - 4 Step -1 'Now check category info
                            'Find out which Category Group the current item in masterList belongs to
                            previousGroup = ClassifyItem_ToGroup(masterList(i))

                            Select Case previousGroup     'Count how many items are in a 
                                Case "GroupA"                'specific group
                                    GroupA_count += 1
                                Case "GroupB"
                                    GroupB_count += 1
                                Case Else
                                    MessageBox.Show("Problem classifying")
                            End Select

                            If i = 0 Then Exit For 'Got to beginning of array so exit

                        Next

                        If GroupA_count <= 3 And GroupB_count <= 3 Then  'If 3 or under then:
                            same4Category = False  'A good thing
                        End If

                End Select

            Loop Until same4Category = False And same2Letters = False

            masterList.Add(tempSelected)  'If passed then add to masterlist
            originalList.RemoveAt(RandomIndex)  'Remove the item from Original List
        Loop

        Me.ListBox1.Items.AddRange(masterList.ToArray) 'ADD items to Listbox

    End Sub

    Private Function ClassifyItem_ToGroup(ByVal currentItem As String) As String

        Select Case currentItem
            Case "A", "B", "C"
                Return "GroupA"
            Case "X", "Y", "Z"
                Return "GroupB"
            Case Else
                Return "NONE"
        End Select

    End Function

[stimbo]

Anyone??