private RandomListNode copyNext (RandomListNode head) {
        RandomListNode headNew  = new RandomListNode(head.label);
        RandomListNode node1 = head.next;
        RandomListNode node2 = headNew;
        map.put(head, headNew);
        RandomListNode node  = null;
        while(node1 != null){
            node = new RandomListNode(node1.label);
            map.put(node1, node);
            node2.next = node;
            node2 = node2.next;
            node1 = node1.next;
        }
        return headNew;
    }