[백준] 1927번 최소 힙 #Java

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.*;

public class Main {

    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int n = Integer.parseInt(br.readLine());
        PriorityQueue<Integer> pq = new PriorityQueue<>();

        for (int i = 0; i < n; i++) {
            int num = Integer.parseInt(br.readLine());

            if(num==0){
                if(!pq.isEmpty()){
                    System.out.println(pq.poll());
                }else{
                    System.out.println(0);
                }
            }else{
                pq.add(num);
            }
        }
    }
}