PriorityQueues.java

import java.util.PriorityQueue;

public class PriorityQueues {

    static class Student implements Comparable<Student>{  // overriding
        String name;
        int rank;

        public Student(String name, int rank){
            this.name = name;
            this.rank = rank;
        }

        @Override
        public int compareTo(Student s2){
            return this.rank -s2.rank;
        }
    }

    public static void main(String[] args) {
        // PriorityQueue<Integer> pq = new PriorityQueue<>();
        // // PriorityQueue<Integer> pq = new PriorityQueue<>(Comparator.reverseOrder());      // For printing in reverse order

        // pq.add(3);   // O(logn)
        // pq.add(4);
        // pq.add(1);
        // pq.add(7);

        // while(!pq.isEmpty()) {
        //     System.out.println(pq.peek());    // O(1)
        //     pq.remove();          // O(logn)
        // }




        // For Student Class

        PriorityQueue<Student> pq = new PriorityQueue<>();
        pq.add(new Student("A", 4));
        pq.add(new Student("B", 5));
        pq.add(new Student("C", 2));
        pq.add(new Student("D", 12));

        while(!pq.isEmpty()) {
            System.out.println(pq.peek().name +" -> "+ pq.peek().rank);    // O(1)
            pq.remove();          // O(logn)
        }
    }
}