Reverse anti clockwise spiral traversal of a binary tree in vb.net

Vb program for Reverse anti clockwise spiral traversal of a binary tree. Here more solutions.

' Include namespace system
Imports System 
'   Vb.net program for
'   Reversal anti clockwise spiral 
'   Traversal of a binary tree 

'  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

'  Define Binary Tree
public Class BinaryTree
    Public  root As TreeNode
    Public Sub New()
        Me.root = Nothing
    End Sub
    '  Find height of given binary tree
    Public Function  treeHeight(ByVal node As TreeNode) As Integer
        if (node IsNot Nothing) Then
            Dim l As Integer = Me.treeHeight(node.left) + 1
            Dim r As Integer = Me.treeHeight(node.right) + 1
            if (l > r) Then
                Return  l
            Else
                Return  r
            End IF
        Else
            Return  0
        End IF
    End Function
    '  Display given level from left to right
    Public Sub printLeftToRight(ByVal node As TreeNode, 
                                ByVal level As Integer)
        if (node  Is  Nothing) Then
            Return
        End If
        if (level = 1) Then
            '  print level node
            Console.Write("  " + node.data.ToString())
        Else
            '  First visit left child
            Me.printLeftToRight(node.left, level - 1)
            Me.printLeftToRight(node.right, level - 1)
        End IF
    End Sub
    '  Display given level from right to left
    Public Sub printRightToLeft(ByVal node As TreeNode, 
                                ByVal level As Integer)
        if (node  Is  Nothing) Then
            Return
        End If
        if (level = 1) Then
            '  print level node
            Console.Write("  " + node.data.ToString())
        Else
            '  First visit right child
            Me.printRightToLeft(node.right, level - 1)
            Me.printRightToLeft(node.left, level - 1)
        End IF
    End Sub
    '  Handles the request of printing reverse
    '  anti clockwise spiral of binary tree
    Public Sub reversalAntiClockwise()
        if (Me.root  Is  Nothing) Then
            Console.WriteLine( vbLf &" Empty Tree ")
        Else
            '  Start level
            Dim top As Integer = 1
            '  Last level
            Dim down As Integer = Me.treeHeight(Me.root)
            '  This is level indicator (top to down selector)
            Dim selection As Boolean = True
            '  When the top level less than or equal to down level
            while (top <= down)
                if (selection = False) Then
                    '  right to left
                    Me.printRightToLeft(Me.root, top)
                    '  Increase level
                    top += 1
                    '  Next is bottom level
                    selection = True
                Else
                    '  left to right
                    Me.printLeftToRight(Me.root, down)
                    '  Decrease the level
                    down -= 1
                    '  Next is top level
                    selection = False
                End IF
            End While
        End IF
    End Sub
    Public Shared Sub Main(ByVal args As String())
        Dim tree As BinaryTree = New BinaryTree()
        '         6   
        '        / \                          
        '       /   \    
        '      4     7    
        '     / \     \               
        '    2   3     12
        '       / \    / 
        '      10  8  5
        '      /    \
        '     9     -1
        '    -----------------
        '    Binary tree

        '  Add node
        tree.root = New TreeNode(6)
        tree.root.left = New TreeNode(4)
        tree.root.left.right = New TreeNode(3)
        tree.root.left.right.left = New TreeNode(10)
        tree.root.left.right.left.left = New TreeNode(9)
        tree.root.left.right.right = New TreeNode(8)
        tree.root.left.right.right.right = New TreeNode(-1)
        tree.root.left.left = New TreeNode(2)
        tree.root.right = New TreeNode(7)
        tree.root.right.right = New TreeNode(12)
        tree.root.right.right.left = New TreeNode(5)
        '  Test
        tree.reversalAntiClockwise()
    End Sub
End Class

Output

  9  -1  6  10  8  5  7  4  2  3  12