uploaded at 2022. 12. 30. 오전 4:40:46

programmers/베스트앨범/solution.java

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+// [문제 링크]: https://school.programmers.co.kr/learn/courses/30/lessons/42579
+
+import java.util.*;
+class Solution {
+    public class Song{
+        private int id;
+        private int plays;
+        public Song(){}
+        public Song(int id, int plays){
+            this.id = id;
+            this.plays = plays;
+        }
+        public int getId(){
+            return id;
+        }
+        public int getPlays(){
+            return plays;
+        }
+        public String toString() {
+            return "Song "+id+" plays"+plays;
+        }
+    }
+    public int[] solution(String[] genres, int[] plays) {
+        HashMap<String,Integer> hm = new HashMap<>();
+        HashMap<String,ArrayList<Song>> hm2 = new HashMap<>();
+        for(int a = 0; a < genres.length; a++){
+            ArrayList<Song> al = new ArrayList<>();
+            hm.put(genres[a],(Integer)(hm.getOrDefault(genres[a],0)+(Integer)plays[a]));
+            al = hm2.getOrDefault(genres[a], al);
+            al.add(new Song(a,plays[a]));
+            hm2.put(genres[a], al);
+        }
+        List<Integer> answer = new ArrayList<>();
+        List<Map.Entry<String, Integer>> entryList = new LinkedList<>(hm.entrySet());
+        entryList.sort(((o1, o2) -> hm.get(o2.getKey()) - hm.get(o1.getKey())));
+        for(Map.Entry<String, Integer> entry : entryList){
+            System.out.println("key : " + entry.getKey() + ", value : " + entry.getValue());
+            ArrayList<Song> al = hm2.get(entry.getKey());
+            al.sort(((o1, o2) -> o2.getPlays() - o1.getPlays()));
+            int idx = 0;
+            for(Song s : al){
+                if(idx++>1) break;
+                answer.add(s.getId());
+                System.out.println(s);
+            }
+        }
+        return answer.stream().mapToInt(Integer::intValue).toArray();
+    }
+}