balanced BT java

// http://code2begin.blogspot.com
// program to check if a given binary tree is a balanced binary tree or not

/**
 * Created by MOHIT on 25-05-2018.
 */

import java.io.*;
import java.lang.reflect.Array;
import java.util.*;

import static java.lang.Integer.max;


// node class
class node{
    int data;
    node left;
    node right;

    // function that returns a pointer to new node
    public node(int element){
        this.data = element;
        this.left = null;
        this.right = null;

    }
};


public class BinaryTree {

    // function to find the height of a binary tree
    static int height(node root){
        if (root == null){
            return 0;
        }
        return (1 + max(height(root.left), height(root.right)));
    }

    // function to check if the tree is a height balanced tree or not
    static boolean isBalanced(node root){
        if(root == null){
            return true;
        }
        // get the heights of the left and the right subtrees
        int left_height = height(root.left);
        int right_height = height(root.right);
        // if the difference between heights of the left and right subtrees is less than 2
        // and left and right subtrees are also balanced then return true
        return Math.abs(left_height - right_height) <= 1 && isBalanced(root.left) && isBalanced(root.right);

    }
    public static void main(String arg[]) {

        // Binary Tree #1
        node head = new node(1);
        head.left = new node(2);
        head.right = new node(3);
        head.left.left = new node(4);
        head.left.right = new node(5);
        head.right.right = new node(6);
        head.left.left.right = new node(7);
        head.right.right.left = new node(8);
        head.left.left.right.left = new node(9);
        head.left.left.right.left.left = new node(10);
        head.right.right.left.right = new node(11);

        // Binary Tree #2
        node head2 = new node(5);
        head2.left = new node(2);
        head2.right = new node(12);
        head2.left.left = new node(-4);
        head2.left.right = new node(3);
        head2.right.left = new node(9);
        head2.right.right = new node(21);
        head2.right.right.left = new node(19);
        head2.right.right.right = new node(25);

        System.out.println("The Binary tree #1 is Balanced : " + isBalanced(head));
        System.out.println("The Binary tree #2 is Balanced : " + isBalanced(head2));

    }
}