Insertion in binary search tree without recursion in c++

C++ program for Insertion in binary search tree without recursion. Here problem description and explanation.

// Include header file
#include <iostream>
using namespace std;
// C++ program for
// iterative insert in binary search tree
class TreeNode
{
	public: 
    int data;
	TreeNode *left;
	TreeNode *right;
	TreeNode(int data)
	{
		this->data = data;
		this->left = nullptr;
		this->right = nullptr;
	}
};
class BinarySearchTree
{
	public: TreeNode *root;
	BinarySearchTree()
	{
		this->root = nullptr;
	}
	//insert a element
	void addNode(int data)
	{
		// Create a new node
		TreeNode *node = new TreeNode(data);
		if (this->root == nullptr)
		{
			// When adds a first node in bst
			this->root = node;
		}
		else
		{
			TreeNode *find = this->root;
			// Add new node to proper position
			while (find != nullptr)
			{
				if (find->data >= data)
				{
					if (find->left == nullptr)
					{
						// When left child empty
						// So add new node here
						find->left = node;
						return;
					}
					else
					{
						// Otherwise
						// Visit left sub-tree
						find = find->left;
					}
				}
				else
				{
					if (find->right == nullptr)
					{
						// When right child empty
						// So add new node here
						find->right = node;
						return;
					}
					else
					{
						// Visit right sub-tree
						find = find->right;
					}
				}
			}
		}
	}
	// Display preorder
	void preorder(TreeNode *node)
	{
		if (node != nullptr)
		{
			// Display node value
			cout << "  " << node->data;
			// Visit to left subtree
			this->preorder(node->left);
			// Visit to right subtree
			this->preorder(node->right);
		}
	}
	void inorder(TreeNode *node)
	{
		if (node != nullptr)
		{
			// Visit to left subtree
			this->inorder(node->left);
			// Display node value
			cout << "  " << node->data;
			// Visit to right subtree
			this->inorder(node->right);
		}
	}
	void postorder(TreeNode *node)
	{
		if (node != nullptr)
		{
			// Visit to left subtree
			this->postorder(node->left);
			// Visit to right subtree
			this->postorder(node->right);
			// Display node value
			cout << "  " << node->data;
		}
	}
};
int main()
{
	BinarySearchTree *tree = new BinarySearchTree();
	/*
	         10
	        / \
	       /   \
	      4     15
	     / \   /
	    3   5 12
	    -------------
	    Build binary search tree

	*/
	tree->addNode(10);
	tree->addNode(4);
	tree->addNode(3);
	tree->addNode(5);
	tree->addNode(15);
	tree->addNode(12);
	// Display tree nodes
	cout << "Preorder " << endl;
	tree->preorder(tree->root);
	cout << "\nInorder " << endl;
	tree->inorder(tree->root);
	cout << "\nPostorder " << endl;
	tree->postorder(tree->root);
	return 0;
}

Output

Preorder
  10  4  3  5  15  12
Inorder
  3  4  5  10  12  15
Postorder
  3  5  4  12  15  10


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