[VB.net][example] Remove all subfolder from a list of Folder

I have a list of folders, where "C:\Source\hidden" and "C:\Source\hidden\hidden" are subFolder of "C:\Source" and "C:\Shit\hidden" and "C:\Shit\hidden\hidden" are subFolder of C:\Shit\", what i want is remove all subFolder from a lists and keep the folders "C:\Source\" and "C:\Shit\" only.

folder structure:

• C:\Source\
• C:\Source\hidden
• C:\Source\hidden\hidden
• C:\Shit\
• C:\Shit\hidden
• C:\Shit\hidden\hidden

Solution:

Module VBModule

    Sub Main()

        Dim dirs As System.Collections.Generic.List(Of String) = new System.Collections.Generic.List(Of String)

        Dim res As System.Collections.Generic.List(Of String) = new System.Collections.Generic.List(Of String)

        dirs.Add("C:\Source\")

        dirs.Add("C:\Source\hidden")

        dirs.Add("C:\Source\hidden\hidden")

        dirs.Add("C:\Shit\")

        dirs.Add("C:\Shit\hidden")

        dirs.Add("C:\Shit\hidden\hidden")

        

        for each dir as String in getRootFolders(dirs)

            Console.WriteLine(dir)

        Next 

    End Sub

    

    private function getRootFolders(ByRef dirs As System.Collections.Generic.List(Of String))As System.Collections.Generic.List(Of String)

        Dim res As System.Collections.Generic.List(Of String) = new System.Collections.Generic.List(Of String)

        If dirs.Count = 0 then return res

            

        dirs.sort()

        res.add(dirs(0))

        

        for i as integer = 1 To dirs.count - 1

            Dim cur As String = dirs(i)

            Dim prev As String = res(res.Count - 1)

            Dim curLen As integer = cur.length

            Dim prevLen As integer = prev.length

            

            ' Path.DirectorySeparatorChar = "\"

            If curLen > prevLen AndAlso cur(prevLen-1) = "\" AndAlso prev.Equals(cur.subString(0, prevLen)) Then

                continue For

            Else

                res.add(cur)

            End if

        Next

        return res

    End Function

End Module

result:

C:\Shit\

C:\Source\

reference:

https://www.geeksforgeeks.org/remove-sub-directories-from-a-file-system/