Imports System
Imports System.Collections.Generic
Public Class Program
Public Shared Sub Main(ByVal args As String())
Dim arr As Integer() = {2, 3, 4, 2, 1, 1, 7, 5, 8, 9, 5, 3, 10, 10}
' 2 + 2 + 3 + 3 + 1 + 1 + 5 + 5 + 10 + 10 = 42 / 2 = 21
Console.WriteLine(SumUniqueNumbers(arr))
End Sub
Public Shared Function SumUniqueNumbers(ByVal arr As Integer()) As Integer
Dim result As Integer = 0
Dim countAppearances As New Dictionary(Of Integer, Integer)
For Each num As Integer In arr
If countAppearances.ContainsKey(num) Then
countAppearances(num) += 1
Else
countAppearances(num) = 1
End If
Next
For Each kvp As KeyValuePair(Of Integer, Integer) In countAppearances
If kvp.Value > 1 Then
result += kvp.Key
End If
Next
Return result
End Function
End Class
' run:
'
' 21
'
