Morris postorder traversal in c#

Csharp program for Morris postorder traversal. Here more information.

// Include namespace system
using System;
/* 
  Csharp program for
  Morris traversal for postorder
*/
// Binary Tree Node
public class TreeNode
{
	public int data;
	public TreeNode left;
	public TreeNode right;
	public TreeNode(int data)
	{
		// Set node value
		this.data = data;
		this.left = null;
		this.right = null;
	}
}
public class BinaryTree
{
	public TreeNode root;
	public BinaryTree()
	{
		// Set the initial value of root
		this.root = null;
	}
	// Recursive function
	// Display postorder view of binary tree
	public void postorder(TreeNode node)
	{
		if (node != null)
		{
			this.postorder(node.left);
			this.postorder(node.right);
			// Print node value
			Console.Write("  " + node.data.ToString());
		}
	}
	// iterative postorder tree traversal
	public void morrisPostorder()
	{
		if (this.root == null)
		{
			return;
		}
		// Create a dummy node
		var dummy_node = new TreeNode(0);
		dummy_node.left = this.root;
		var current = dummy_node;
		// Define some useful variables
		TreeNode parent = null;
		TreeNode middle = null;
		TreeNode auxiliary = null;
		TreeNode back = null;
		// iterating tree nodes
		while (current != null)
		{
			if (current.left == null)
			{
				// When left child are empty then
				// Visit to right child
				current = current.right;
			}
			else
			{
				// Get to left child
				auxiliary = current.left;
				while (auxiliary.right != null && auxiliary.right != current)
				{
					auxiliary = auxiliary.right;
				}
				if (auxiliary.right != current)
				{
					auxiliary.right = current;
					current = current.left;
				}
				else
				{
					parent = current;
					middle = current.left;
					// Update new path
					while (middle != current)
					{
						back = middle.right;
						middle.right = parent;
						parent = middle;
						middle = back;
					}
					parent = current;
					middle = auxiliary;
					// Print the resultant nodes.
					// And correct node link in current path
					while (middle != current)
					{
						Console.Write("  " + middle.data.ToString());
						back = middle.right;
						middle.right = parent;
						parent = middle;
						middle = back;
					}
					// Unlink previous bind element
					auxiliary.right = null;
					// Visit to right child
					current = current.right;
				}
			}
		}
		Console.Write("\n");
	}
	public static void Main(String[] args)
	{
		// Create new tree
		var tree = new BinaryTree();
		/*
		    Create Binary Tree
		         4
		       /   \
		      8     3
		     / \   / \
		    1   6 7   2
		       /   \   \
		      9     10  11
		*/
		// Add tree node
		tree.root = new TreeNode(4);
		tree.root.left = new TreeNode(8);
		tree.root.left.left = new TreeNode(1);
		tree.root.right = new TreeNode(3);
		tree.root.right.right = new TreeNode(2);
		tree.root.right.right.right = new TreeNode(11);
		tree.root.right.left = new TreeNode(7);
		tree.root.right.left.right = new TreeNode(10);
		tree.root.left.right = new TreeNode(6);
		tree.root.left.right.left = new TreeNode(9);
		Console.WriteLine("\n Recursive Postorder");
		// Display Tree elements
		tree.postorder(tree.root);
		Console.WriteLine("\n Morris Postorder");
		tree.morrisPostorder();
	}
}

Output

 Recursive Postorder
  1  9  6  8  10  7  11  2  3  4
 Morris Postorder
  1  9  6  8  10  7  11  2  3  4