Question

I have a List object and I want to remove the duplicated items but leaving at least one of the duplicated items in the list;

I wrote something like this however I would optimize this code for better performance, is there something faster?

Const chars As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
Dim rnd As New Random()
Dim mylist As List(Of String) = Enumerable.Range(1, 100).Select(Function(i) chars(rnd.Next(0, chars.Length)).ToString).ToList

For n As Integer = mylist.Count - 1 To n = 0 Step -1

    'remove the item if it's duplicated
    'but leave at least one of the duplicated items in the list
    If mylist.IndexOf(mylist.Item(n), 0) < n Then
        mylist.RemoveAt(n)
    End If

Next

Answer 1

Have you tried .Distinct()

Dim stringWithChars As String = "AABBCCDDEEFFaabbccddeeff"
Dim res = stringWithChars.Distinct() // ABCDEFabcdef

Edit: Since you didn’t say which framework you use, I suppose you can use Linq ( .NET 3.5 +)