Imports System
Friend Class Program
Friend Shared Function countOddProductPairs(ByVal arr As Integer()) As Integer
Dim odd As Integer = 0
For i As Integer = 0 To arr.Length - 1
If arr(i) Mod 2 <> 0 Then
odd += 1
End If
Next
Return odd * (odd - 1)
End Function
Friend Shared Function countEvenProductPairs(ByVal total_odd_product_pairs As Integer, ByVal arr As Integer()) As Integer
Dim total_pairs As Integer = arr.Length * (arr.Length - 1)
Return total_pairs - total_odd_product_pairs
End Function
Public Shared Sub Main(ByVal args As String())
Dim arr As Integer() = New Integer() {1, 8, 5}
' The pairs are: (1, 8), (1, 5), (8, 1), (8, 5), (5, 1), (5, 8)
' Pairs with Even product: (1, 8), (8, 1), (8, 5), (5, 8) = 4
' Total pairs with Odd product: (1, 5), (1, 5) = 2
Dim total_odd_product_pairs As Integer = countOddProductPairs(arr)
Dim total_even_product_pairs As Integer = countEvenProductPairs(total_odd_product_pairs, arr)
Console.WriteLine("Total Even Product Pairs = " & total_even_product_pairs)
Console.WriteLine("Total Odd Product Pairs= " & total_odd_product_pairs)
End Sub
End Class
' run:
'
' Total Even Product Pairs = 4
' Total Odd Product Pairs= 2
'
