프로그래머스[해시] 베스트앨범

참고 : https://velog.io/@hyeon930/%ED%94%84%EB%A1%9C%EA%B7%B8%EB%9E%98%EB%A8%B8%EC%8A%A4-%EB%B2%A0%EC%8A%A4%ED%8A%B8%EC%95%A8%EB%B2%94-Java

wow...
String형의 비교를 != 로 해서 다 풀어놓고 계속 틀렸었다.
https://youngjinmo.github.io/2019/12/boolean-string/
내일 정리해야지

import java.util.*;

public class Solution_BestAlbum {
    public static int[] solution(String[] genres, int[] plays) {
        ArrayList<Music> list = new ArrayList<>();
        ArrayList<Integer> bestList = new ArrayList<>();
        Map<String, Integer> genreMap = new HashMap<>();
        Map<String, Integer> musicMap = new HashMap<>();

        for(int i = 0; i < genres.length; i ++) {
            list.add(new Music(i, genres[i], plays[i]));

            if(genreMap.containsKey(genres[i])) {
                genreMap.put(genres[i], genreMap.get(genres[i]) + plays[i]);
            } else {
                genreMap.put(genres[i], plays[i]);
            }
        }

        Collections.sort(list, new Comparator<Music>() {
                    @Override
                    public int compare(Music o1, Music o2) {

                        if(o1.genre.equals(o2.genre)) {
                            System.out.println("장르가 같을때 주소");
                            System.out.println(System.identityHashCode(o1.genre));
                            System.out.println(System.identityHashCode(o2.genre));
                            if(o1.play == o2.play) {
                                return o1.id - o2.id;
                            } else {
                                return o2.play - o1.play;
                            }
                        } else {
                            return genreMap.get(o2.genre) - genreMap.get(o1.genre);
                        }
                    }
                });

        for(Music music : list) {
            if(!musicMap.containsKey(music.genre)) {
                musicMap.put(music.genre, 1);
                bestList.add(music.id);
            } else {
                int genreCnt = musicMap.get(music.genre);
                if(genreCnt >= 2)
                    continue;
                else {
                    musicMap.put(music.genre, genreCnt + 1);
                    bestList.add(music.id);
                }
            }
        }

        int[] answer = new int[bestList.size()];
        for(int i = 0; i < answer.length; i ++) {
            answer[i] = bestList.get(i);
        }

        return answer;
    }
/*
    public static void main(String[] args) {
        String[] genres = {"classic", "pop", "classic", "classic", "pop"};
        int[] plays = {500, 600, 150, 800, 2500};
        int[] answer = solution(genres, plays);

        for(int i = 0; i < answer.length; i ++) {
            System.out.println(answer[i]);
        }
    }
    */
}

class Music {
    int id;
    String genre;
    int play;

    Music(int i, String g, int p) {
        this.id = i;
        this.genre = g;
        this.play = p;
    }

}