How does a priority queue work in Java using a heap?

How does a priority queue work in Java using a heap?

A priority queue in Java can be implemented using a heap data structure, which allows for efficient retrieval of the highest (or lowest) priority element.

Can you explain how to implement it in code?

Sure! You can use the PriorityQueue class in Java, which is backed by a heap. Here's a simple example:

import java.util.PriorityQueue;

public class Main {
    public static void main(String[] args) {
        PriorityQueue<Integer> pq = new PriorityQueue<>();
        pq.add(5);
        pq.add(1);
        pq.add(3);

        while (!pq.isEmpty()) {
            System.out.println(pq.poll()); // prints elements in ascending order
        }
    }
}

What are the time complexities for adding and removing elements?

Adding an element takes O(log n) time, and removing the highest priority element also takes O(log n) time due to the heap structure.

Are there any limitations to using a priority queue?

Yes, priority queues can have limitations such as not allowing duplicate priorities and potentially higher memory usage compared to simpler data structures.