debug.java

class node {
    int data;
    node left;
    node right;
    public node(int data) {
        this.data = data;
        left = right = null;
    }
}

public class debug{
    node root;

    public void insert()
    {
//        node root = new node(60);
        node n1 = new node(50);
        node n2 = new node(40);
        node n3 = new node(30);
        node n4 = new node(20);

        root = n1;
        root.left = n2;
        root.right = n3;
        root.left.left=n4 ;     //or we can write    n1.left = n3;
//        root.right.right = n4;   // or we can write   n2.right = n4;


    }

    public void preOrderTraversal(node root){
        if(root==null) {
            return;
        }
        System.out.println(root.data);
        preOrderTraversal(root.left);
        preOrderTraversal(root.right);
    }
}

class Garima
{
    public static void main(String[] args) {

        debug obj1 = new debug();

        obj1.insert();
        obj1.preOrderTraversal(obj1.root);
    }
}