Question
Consider the following Java code snippet: Â Â
import java.util.PriorityQueue;   public class HeapQuestion8 {     public static void main(String[] args) {       PriorityQueue pq = new PriorityQueue();       pq.add(5);       pq.add(1);       pq.add(5); // Adding a duplicate       pq.add(3);       System.out.println(pq.poll());       System.out.println(pq.poll());       System.out.println(pq.poll());     }   }   What will be the output of this program?Solution
A PriorityQueue (min-heap by default for Integers) correctly handles duplicate elements. They are treated like any other element based on their priority.   1. pq.add(5); pq.add(1); pq.add(5); pq.add(3);     The elements in the heap are {1, 3, 5, 5} (conceptually, 1 is at the root).   2. System.out.println(pq.poll());     Removes and prints the smallest element: 1. The heap now contains {3, 5, 5}.   3. System.out.println(pq.poll());     Removes and prints the next smallest element: 3. The heap now contains {5, 5}.   4. System.out.println(pq.poll());     Removes and prints the next smallest element: 5. The heap now contains {5}.   Therefore, the output is 1, 3, 5.
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