Data commit

Task/Attractive-numbers/Visual-Basic-.NET/attractive-numbers.vb

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+Module Module1
+    Const MAX = 120
+
+    Function IsPrime(n As Integer) As Boolean
+        If n < 2 Then Return False
+        If n Mod 2 = 0 Then Return n = 2
+        If n Mod 3 = 0 Then Return n = 3
+        Dim d = 5
+        While d * d <= n
+            If n Mod d = 0 Then Return False
+            d += 2
+            If n Mod d = 0 Then Return False
+            d += 4
+        End While
+        Return True
+    End Function
+
+    Function PrimefactorCount(n As Integer) As Integer
+        If n = 1 Then Return 0
+        If IsPrime(n) Then Return 1
+        Dim count = 0
+        Dim f = 2
+        While True
+            If n Mod f = 0 Then
+                count += 1
+                n /= f
+                If n = 1 Then Return count
+                If IsPrime(n) Then f = n
+            ElseIf f >= 3 Then
+                f += 2
+            Else
+                f = 3
+            End If
+        End While
+        Throw New Exception("Unexpected")
+    End Function
+
+    Sub Main()
+        Console.WriteLine("The attractive numbers up to and including {0} are:", MAX)
+        Dim i = 1
+        Dim count = 0
+        While i <= MAX
+            Dim n = PrimefactorCount(i)
+            If IsPrime(n) Then
+                Console.Write("{0,4}", i)
+                count += 1
+                If count Mod 20 = 0 Then
+                    Console.WriteLine()
+                End If
+            End If
+                i += 1
+        End While
+        Console.WriteLine()
+    End Sub
+
+End Module