' 8^2 + 2^2 = 68
' 6^2 + 8^2 = 100
' 1^2 + 0^2 + 0^2 = 1 = happy number
Imports System
Public Class Program
Public Shared Function isHappyNumber(ByVal num As Integer) As Integer
Dim sum As Integer = 0
While num > 0
Dim reminder As Integer = num Mod 10
sum = sum + (reminder * reminder)
num = num \ 10
End While
Return sum
End Function
Public Shared Sub Main(ByVal args As String())
Dim N As Integer = 100
For i As Integer = 1 To N
Dim num As Integer = i
Dim result As Integer = num
While result <> 1 AndAlso result <> 4
result = isHappyNumber(result)
End While
If result = 1 Then
Console.Write(num & " ")
End If
Next
End Sub
End Class
' run:
'
' 1 7 10 13 19 23 28 31 32 44 49 68 70 79 82 86 91 94 97 100
'
