Imports System
Public Class Test
Public Shared Function number_exist_few_times(arr() As Integer, number As Integer, index As Integer) As Boolean
For i As Integer = 0 To arr.Length - 1
If arr(i) = number AND i <> index Then
return true
End If
Next
return false
End Function
Public Shared Function get_single_number(arr() As Integer) As Integer
For i As Integer = 0 To arr.Length - 1
If Not number_exist_few_times(arr, arr(i), i) Then
return arr(i)
End If
Next
return -1
End Function
Public Shared Sub Main()
Dim arr() As Integer = {3, 2, 1, 2, 3, 3, 1, 5, 9, 7, 7, 9, 9}
System.Console.WriteLine(get_single_number(arr))
End Sub
End Class
' Run
'
' 5
