public static void main(String args[]){
        BinaryTree bt = new BinaryTree();
        Node head = null;
        head = bt.addNode(10, head);
        head = bt.addNode(15, head);
        head = bt.addNode(5, head);
        head = bt.addNode(7, head);
        head = bt.addNode(19, head);
        head = bt.addNode(20, head);
        head = bt.addNode(-1, head);
        head = bt.addNode(21, head);
        System.out.println(bt.height(head));
        
    }
Date 07/07/2014 
@author tusroy

Youtube link - https://youtu.be/bmaeYtlO2OE
Youtube link - https://youtu.be/_SiwrPXG9-g
Youtube link - https://youtu.be/NA8B84DZYSA
src/com/interview/tree/BinaryTree.java