Check for continuous binary tree in vb.net

Vb program for Check for continuous binary tree. Here problem description and other solutions.

' Include namespace system
Imports System 
'  Vb.net program for
'  Check if binary tree is continuous tree
'  Using recursion

'  Binary Tree Node
Public Class TreeNode
    Public  data As Integer
    Public  left As TreeNode
    Public  right As TreeNode
    Public Sub New(ByVal data As Integer)
        '  Set node value
        Me.data = data
        Me.left = Nothing
        Me.right = Nothing
    End Sub
End Class

public Class BinaryTree
    Public  root As TreeNode
    Public Sub New()
        '  Set initial tree root
        Me.root = Nothing
    End Sub
    Public Function  absValue(ByVal num As Integer) As Integer
        if (num < 0) Then
            Return  -num
        End If
        Return  num
    End Function
    '  Check tree is continuous or not
    Public Function  isContinuous(ByVal node As TreeNode) As Boolean
        if (node IsNot Nothing) Then
            if ((node.left IsNot Nothing AndAlso 
                 Me.absValue(node.data - node.left.data) <> 1) OrElse 
            (node.right IsNot Nothing AndAlso 
                Me.absValue(node.data - node.right.data) <> 1)) Then
                '  Case
                '  When fail continuous tree rule
                Return  False
            End If
            if (Me.isContinuous(node.left) AndAlso 
                Me.isContinuous(node.right)) Then
                Return  True
            End If
            '  When node value is not satisfied
            '   continuous tree properties
            Return  False
        End If
        Return  True
    End Function
    Public Shared Sub Main(ByVal args As String())
        '  Create new tree
        Dim tree As BinaryTree = New BinaryTree()
        '   Binary Tree
        '   ------------
        '       5
        '     /   \
        '    4     4
        '   /     /  \
        '  3     5    3
        '   \
        '    2
        '  Add tree node
        tree.root = New TreeNode(5)
        tree.root.left = New TreeNode(4)
        tree.root.right = New TreeNode(4)
        tree.root.left.left = New TreeNode(3)
        tree.root.right.right = New TreeNode(3)
        tree.root.right.left = New TreeNode(5)
        tree.root.left.left.right = New TreeNode(2)
        if (tree.isContinuous(tree.root) = True) Then
            Console.WriteLine("Continuous Tree ")
        Else
            Console.WriteLine("Not Continuous Tree ")
        End IF
        '  Case 2
        '       5
        '     /   \
        '    4     4
        '   /     /  \
        '  3     5    3
        '   \
        '    1  <--- change value
        tree.root.left.left.right.data = 1
        if (tree.isContinuous(tree.root) = True) Then
            Console.WriteLine("Continuous Tree ")
        Else
            Console.WriteLine("Not Continuous Tree ")
        End IF
    End Sub
End Class

Output

Continuous Tree
Not Continuous Tree