diameter bt java

// http://code2begin.blogspot.com
// program to print the diameter of a given binary trees

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

import java.util.*;

// 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 print the diameter of a binary tree
    static int diameter(node root){
        if (root == null){
            return 0;
        }

        int left_height = height(root.left);
        int right_height = height(root.right);

        int left_diameter = diameter(root.left);
        int right_diameter = diameter(root.right);

        return max( left_height + right_height + 1 , max(left_diameter, right_diameter) );
    }


    public static void main(String arg[]) {
        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);
        System.out.print("Diameter of the Above binary tree is : " + diameter(head));
    }
}