Determine if a binary tree is height-balanced?

/* Java program to determine if binary tree is
height balanced or not */

/* A binary tree node has data, pointer to left child,
and a pointer to right child */
class Node {
	int data;
	Node left, right;
	Node(int d)
	{
		data = d;
		left = right = null;
	}
}

class BinaryTree {
	Node root;

	/* Returns true if binary tree with root as root is
	* height-balanced */
	boolean isBalanced(Node node)
	{
		int lh; /* for height of left subtree */

		int rh; /* for height of right subtree */

		/* If tree is empty then return true */
		if (node == null)
			return true;

		/* Get the height of left and right sub trees */
		lh = height(node.left);
		rh = height(node.right);

		if (Math.abs(lh - rh) <= 1 && isBalanced(node.left)
			&& isBalanced(node.right))
			return true;

		/* If we reach here then tree is not height-balanced
		*/
		return false;
	}

	/* UTILITY FUNCTIONS TO TEST isBalanced() FUNCTION */
	/* The function Compute the "height" of a tree. Height
	is the number of nodes along the longest path from
	the root node down to the farthest leaf node.*/
	int height(Node node)
	{
		/* base case tree is empty */
		if (node == null)
			return 0;

		/* If tree is not empty then height = 1 + max of
		left height and right heights */
		return 1
			+ Math.max(height(node.left),
					height(node.right));
	}

	public static void main(String args[])
	{
		BinaryTree tree = new BinaryTree();
		tree.root = new Node(1);
		tree.root.left = new Node(2);
		tree.root.right = new Node(3);
		tree.root.left.left = new Node(4);
		tree.root.left.right = new Node(5);
		tree.root.left.left.left = new Node(8);

		if (tree.isBalanced(tree.root))
			System.out.println("Tree is balanced");
		else
			System.out.println("Tree is not balanced");
	}
}

// This code has been contributed by Mayank
// Jaiswal(mayank_24)