Imports System
Imports System.Text
Imports System.Collections.Generic
Public Class Program
Public Shared Function removeNonDuplicate(ByVal str As String) As String
Dim arr As Char() = str.ToCharArray()
Dim duplicateList As IList(Of Char) = New List(Of Char)()
For Each ch As Char In arr
If str.IndexOf(ch) <> str.LastIndexOf(ch) Then
duplicateList.Add(ch)
End If
Next
Dim duplicateString As StringBuilder = New StringBuilder()
For Each ch As Char In duplicateList
duplicateString.Append(ch)
Next
Return duplicateString.ToString()
End Function
Public Shared Sub Main(ByVal args As String())
Dim str As String = "Bubble Occurrence Mammal vb"
Console.WriteLine(removeNonDuplicate(str))
End Sub
End Class
' run:
'
' ubble ccurrece ammal b
'
