2019 KAKAO BLIND RECRUITMENT : 실패율

https://programmers.co.kr/learn/courses/30/lessons/42889

코딩테스트 연습 - 실패율

// 커스텀 정렬하는 법을 익히자...!!

// 코드

import java.util.*;
 
class Solution {
    
    class Fail { 
        int stage;
        double rate; 
        Fail(int stage, double rate) {
            this.stage = stage;
            this.rate  = rate;
        } 
    }
/*
===============================================
리턴값 | 뜻 
===============================================
 -1  | 결과적으로 left가 왼쪽에 와야한다.
 0   | 결과적으로 left와 right가 같다.
 1   | 결과적으로 left가 오른쪽에 와야한다.
===============================================
*/
    Comparator<Fail> comp = new Comparator<>() {
        public int compare(Fail a, Fail b) {
            if(a.rate < b.rate) return 1;
            else if(a.rate > b.rate) return -1;
            else {
                if(a.stage > b.stage) return 1;
                else if(a.stage < b.stage) return -1;
                else return 0;
            }
        }
    }; 
    
    public int[] solution(int N, int[] stages) {
        int[] answer = new int[N];
        List<Fail> fails = new ArrayList<>();        
        int total = stages.length;
        
        int[] users = new int[N + 1];
        for(int stage : stages) users[stage-1]++;
        
        for(int i=0; i<N; ++i) {
            if(users[i] == 0) fails.add(new Fail(i+1, 0));
            else {fails.add(new Fail(i+1, (double)users[i]/total)); total -= users[i];}
        }
        
        Collections.sort(fails, comp);
        for(int i=0; i<N; ++i) answer[i] = fails.get(i).stage;
        
        return answer;
    }
}