백준 1927 자바 - 최소 힙

// 최소 힙
package Silver_II_2;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.PriorityQueue;

public class Ex1927 {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        int n = Integer.parseInt(br.readLine());

        PriorityQueue<Integer> maxHeap = new PriorityQueue<>();

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

            if (x == 0) {
                if (maxHeap.isEmpty()) {
                    maxHeap.add(0);
                }
                System.out.println(maxHeap.poll());
            } else {
                maxHeap.add(x);
            }
        }
    }
}