Heaps

Heaps (Priority Queues in Java)

Heaps are implemented using the PriorityQueue class in Java.

• Efficient Seek Time: Provides O(1) time complexity for accessing the highest priority element.

  PriorityQueue<Integer> pq = new PriorityQueue<>();
  pq.add(10);
  pq.add(20);
  pq.add(15);
  System.out.println("Highest priority element: " + pq.peek());
  

• Null Elements: Does not allow null elements.

  PriorityQueue<Integer> pq = new PriorityQueue<>();
  pq.add(null); // throws NullPointerException
  

• Element Ordering: Elements are ordered based on their natural ordering or by a Comparator specified at the time of queue construction.

  PriorityQueue<Integer> naturalOrderQueue = new PriorityQueue<>();
  PriorityQueue<Integer> customOrderQueue = new PriorityQueue<>(Comparator.reverseOrder());
  

---

Heap as a Priority Queue in java

Methods :

• add(E e) Inserts the specified element into this priority queue.
• offer(E e) Inserts the specified element into this priority queue
• poll()Retrieves and removes the head of this queue, or returns null if this queue is empty.