Method addFirst

12_LinkedList.java/DLL.java:18–29

(int data)

        public static int size;

        public void addFirst(int data) {
            size++;
            Node newNode = new Node(data);
            if(head == null) {
                head = tail = newNode;
                return;
            }

            head.prev = newNode;
            newNode.next = head;
            head = newNode;
        }

        public void print() {
            Node temp = head;