Imports System
Imports System.Collections.Generic
Public Class Program
Public Shared Function get_first_repeating_element(ByVal arr As Integer()) As Integer
Dim x As Integer = -1
Dim st As HashSet(Of Integer) = New HashSet(Of Integer)()
For i As Integer = arr.Length - 1 To 0 step -1
If st.Contains(arr(i)) Then
x = i
Else
st.Add(arr(i))
End If
Next
If x <> -1 Then Return arr(x)
Return -1
End Function
Public Shared Sub Main()
Dim arr As Integer() = New Integer() {1, 2, 4, 5, 6, 5, 4, 3, 7}
Dim n As Integer = get_first_repeating_element(arr)
If n <> -1 Then
Console.WriteLine("First repeating element is: " & n)
Else
Console.WriteLine("No repeating elements")
End If
End Sub
End Class
' run:
'
' First repeating element is: 4
'
