牛客网真题-72-最大点集

优先级队列(最大堆)，X从大到小遍历每一个点，y应该是逐渐递增的，当y减小时，这个点不满足。
但是只能过60%数据，复杂度过大。优化：按照y降序，x升序，过了70%或者80%；不会优化了

import java.util.PriorityQueue;
import java.util.Scanner;
public class Main {
    static class Node {
        public int x;
        public int y;

        public Node(int x, int y){
            this.x = x;
            this.y = y;
        }
    }

    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        PriorityQueue<Node> priorityQueue = new PriorityQueue<>((o1, o2) -> {
            if(o1.y == o2.y){
                return Integer.compare(o1.x, o2.x);
            }else{
                return Integer.compare(o2.y, o1.y);
            }
        });

        for(int i = 0; i < n; i++){
            priorityQueue.add(new Node(scanner.nextInt(), scanner.nextInt()));
        }
        int x = 0;
        while (!priorityQueue.isEmpty()) {
            Node temp = priorityQueue.poll();
            if(temp.x >= x){
                x = temp.x;
                System.out.println(temp.x + " " + temp.y);
            }
        }
    }
}