public static DoublyLinkedListNode sortedInsert(DoublyLinkedListNode llist, int data) {
        DoublyLinkedListNode target = llist;
        while (target.next != null && target.next.data < data) {
            target = target.next;      
        }
        DoublyLinkedListNode insert = new DoublyLinkedListNode(data);
        if (target.data < data) {
            DoublyLinkedListNode after = target.next;
            target.next = insert;
            insert.prev = target;
            insert.next = after;
        } else {
            insert.next = target;
            llist = insert;
        }
        return llist;
    }