Big O week 3 day 6 p2

public static Node flattenLinkedList(Node head) {
        Node tmp = head;
        PriorityQueue<Integer> pq=new PriorityQueue<>();
        while(tmp != null){
            Node tmp2 = tmp;
            while(tmp2 != null){
                pq.add(tmp2.data);
                tmp2 = tmp2.child;
            }
            tmp = tmp.next;
        }
        Node ans = new Node(100);
        tmp = ans;
        while(!pq.isEmpty()){
            int data = pq.poll();
            Node x = new Node(data);
            tmp.child = x;
            tmp = tmp.child;
        }
        return ans.child;
    }