실패율

import java.util.*;
class Solution {
    public int[] solution(int N, int[] stages) {
        int[] answer = new int[N];
        int[] tries = new int[N+2];
        int[] stay = new int[N+2];
        for(int i=0; i<stages.length; i++){
            stay[stages[i]]++;
            for(int j=1; j<=stages[i];j++){
                tries[j]++;
            }
        }
        Stage[] rates = new Stage[N+1];
        rates[0] = new Stage(0,-1);
        for(int i=1; i<rates.length; i++){
            if(tries[i]==0){
                rates[i] = new Stage(i,(double)0); 
            }else{
                rates[i] = new Stage(i,(double)stay[i]/tries[i]); 
            }
        }
        Arrays.sort(rates);
        for(int i=0; i<answer.length; i++){
            answer[i] = rates[i].num;
        }
        
        return answer;
    }

}

class Stage implements Comparable<Stage> {
    int num; double rate;
    Stage(int num, double rate) {
        this.num = num; this.rate = rate; 
    }
    @Override
    public int compareTo(Stage other) {
        return Double.compare(other.rate, this.rate); 
    }
}