최대 강연료는 얼마?

그리디 

import java.util.*;
import java.util.stream.Stream;

class Money{
    int Money;
    int time;

    public Money(int money, int time) {
        this.Money = money;
        this.time = time;
    }

    public int getMoney() {
        return Money;
    }

    public int getTime() {
        return time;
    }
}

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt(); // 배열의 크기
        ArrayList<Money> arrayList = new ArrayList<>();


        for(int i = 0; i < N; i++){
            int height = sc.nextInt();
            int weight = sc.nextInt();
            arrayList.add(new Money(height, weight));
        }

        Collections.sort(arrayList, (Money x, Money y) -> y.time - x.time);


        Main T = new Main();
        System.out.println(T.solution(arrayList));
    }

    public int solution(ArrayList<Money> arr){
        Money max = arr.stream().max((x, y) -> Integer.compare(x.getTime(), y.getTime())).get();
        PriorityQueue<Integer> priorityQueue = new PriorityQueue<>(Collections.reverseOrder());
        int cnt = 0;
        int j = 0;// 다시 초기화가 안되게끔
        for(int i = max.time; i >=1 ; i--){
            for( ; j < arr.size(); j++){
                if(arr.get(j).time < i){
                    break;
                }
                priorityQueue.offer(arr.get(j).Money);
            }

            if(!priorityQueue.isEmpty()){
                cnt += priorityQueue.poll();
            }

        }
      return cnt;
    }
}