Avl tree node insertion in c++

C++ program for Avl tree node insertion. Here problem description and other solutions.

// Include header file
#include <iostream>
using namespace std;
// C++ program
// AVL Tree insertion

// Avl Tree Node
class TreeNode
{
	public: 
    int data;
	int height;
	TreeNode *left;
	TreeNode *right;
	TreeNode(int data)
	{
		// Set node value of avl tree
		this->data = data;
		this->height = 1;
		this->left = nullptr;
		this->right = nullptr;
	}
};
class AvlTree
{
	public:
	// Tree root node
	TreeNode *root;
	AvlTree()
	{
		this->root = nullptr;
	}
	// Get the height of given node
	int getHeight(TreeNode *node)
	{
		if (node == nullptr)
		{
			return 0;
		}
		return node->height;
	}
	// Get the max value of given two numbers
	int maxHeight(int a, int b)
	{
		if (a > b)
		{
			return a;
		}
		else
		{
			return b;
		}
	}
	// Perform the Right rotate operation
	TreeNode *rightRotate(TreeNode *node)
	{
		// Get left child node
		TreeNode *leftNode = node->left;
		// Get left node right subtree
		TreeNode *rightSubtree = leftNode->right;
		// Update the left and right subtree
		leftNode->right = node;
		node->left = rightSubtree;
		// Change the height of modified node
		node->height = this->maxHeight(
          this->getHeight(node->left), 
          this->getHeight(node->right)) + 1;
		leftNode->height = this->maxHeight(
          this->getHeight(leftNode->left), 
          this->getHeight(leftNode->right)) + 1;
		return leftNode;
	}
	// Perform the Left Rotate operation
	TreeNode *leftRotate(TreeNode *node)
	{
		// Get right child node
		TreeNode *rightNode = node->right;
		// Get right node left subtree
		TreeNode *leftSubtree = rightNode->left;
		// Update the left and right subtree
		rightNode->left = node;
		node->right = leftSubtree;
		// Change the height of modified node
		node->height = this->maxHeight(
          this->getHeight(node->left), 
          this->getHeight(node->right)) + 1;
		rightNode->height = this->maxHeight(
          this->getHeight(rightNode->left), 
          this->getHeight(rightNode->right)) + 1;
		return rightNode;
	}
	// Get the balance factor
	int getBalanceFactor(TreeNode *node)
	{
		if (node == nullptr)
		{
			return 0;
		}
		return this->getHeight(node->left) - 
          this->getHeight(node->right);
	}
	// Recursively, add a node in AVL tree
	// Duplicate keys (data) are not allowed
	TreeNode *addNode(TreeNode *node, int data)
	{
		if (node == nullptr)
		{
			// Return a new node
			return new TreeNode(data);
		}
		if (data < node->data)
		{
			node->left = this->addNode(node->left, data);
		}
		else if (data > node->data)
		{
			node->right = this->addNode(node->right, data);
		}
		else
		{
			// When given key data already exists
			return node;
		}
		// Change the height of current node
		node->height = 1 + this->maxHeight(
          this->getHeight(node->left), 
          this->getHeight(node->right));
		// Get balance factor of a node
		int factor = this->getBalanceFactor(node);
		// LL Case
		if (factor > 1 && data < node->left->data)
		{
			return this->rightRotate(node);
		}
		// RR Case
		if (factor < -1 && data > node->right->data)
		{
			return this->leftRotate(node);
		}
		// LL Case
		if (factor > 1 && data > node->left->data)
		{
			node->left = this->leftRotate(node->left);
			return this->rightRotate(node);
		}
		// RR Case
		if (factor < -1 && data < node->right->data)
		{
			node->right = this->rightRotate(node->right);
			return this->leftRotate(node);
		}
		return node;
	}
	// Print the tree in preorder form
	void preorder(TreeNode *node)
	{
		if (node != nullptr)
		{
			cout << "  " << node->data;
			this->preorder(node->left);
			this->preorder(node->right);
		}
	}
	// Print the tree in inorder form
	void inorder(TreeNode *node)
	{
		if (node != nullptr)
		{
			this->inorder(node->left);
			cout << "  " << node->data;
			this->inorder(node->right);
		}
	}
	// Print the tree in postorder form
	void postorder(TreeNode *node)
	{
		if (node != nullptr)
		{
			this->postorder(node->left);
			this->postorder(node->right);
			cout << "  " << node->data;
		}
	}
};
int main()
{
	AvlTree *tree = new AvlTree();
	// Add tree node
	tree->root = tree->addNode(tree->root, 4);
	tree->root = tree->addNode(tree->root, 7);
	tree->root = tree->addNode(tree->root, 5);
	tree->root = tree->addNode(tree->root, 19);
	tree->root = tree->addNode(tree->root, 17);
	tree->root = tree->addNode(tree->root, 13);
	tree->root = tree->addNode(tree->root, 11);
	tree->root = tree->addNode(tree->root, 3);
	tree->root = tree->addNode(tree->root, 2);
	tree->root = tree->addNode(tree->root, -3);
	/*
	  Resultant  AVL Tree
	  -----------------
	         7
	        /  \ 
	       /    \
	      4      17
	     / \     / \
	    2   5  13  19
	   / \     /
	 -3   3   11
	*/
	cout << "Resultant AVL Tree";
	cout << "\nPreorder  :";
	tree->preorder(tree->root);
	cout << "\nInorder   :";
	tree->inorder(tree->root);
	cout << "\nPostorder :";
	tree->postorder(tree->root);
	return 0;
}

Output

Resultant AVL Tree
Preorder  :  7  4  2  -3  3  5  17  13  11  19
Inorder   :  -3  2  3  4  5  7  11  13  17  19
Postorder :  -3  3  2  5  4  11  13  19  17  7


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