[Programmers] Lv1: 실패율(42889)

문제

- 링크: https://school.programmers.co.kr/learn/courses/30/lessons/42889?language=java

 

풀이

import java.util.HashMap;

class Solution {
    public int[] solution(int N, int[] stages) {

        int[] challenger = new int[N + 2];
        for (int i = 0; i < stages.length; ++i) {
            challenger[stages[i]] += 1;
        }
        

        HashMap<Integer, Double> fails = new HashMap<>();
        double total = stages.length;
        

        for (int i = 1; i <= N; ++i) {
            if (challenger[i] == 0) { 
                fails.put(i, 0.);
            }
            else {
                fails.put(i, challenger[i] / total);
                total -= challenger[i];
            }
        }

        return fails.entrySet().stream().sorted((o1, o2) -> Double.compare(o2.getValue(), o1.getValue())).mapToInt(HashMap.Entry::getKey).toArray();
    }
}