PriorityQueue

PriorityQueue<Integer> pq = new PriorityQueue<>();
        pq.add(1);
        pq.add(2);
        pq.remove(1);
        pq.contains(1);
        pq.clear();
        pq.peek();
        pq.poll();
        pq.offer(1);
        pq.size();
        pq.toArray();
        Queue<Integer> maxHeap = new PriorityQueue<>((a1, a2) -> (a2 - a1));