public Node insert(Node root, int data) {
        Node node = new Node(data);

        if (root == null)
            return node;

        Node parent = null;
        Node current = root;

        while (current != null) {
            parent = current;
            if (current.data <= data)
                current = current.right;
            else
                current = current.left;
        }

        if (parent.data <= data)		// can't I avoid using parent and just assign node to current? I think 2 variable use karna waste hai is case me.
            parent.right = node;
        else
            parent.left = node;

        return root;
    }