프로그래머스-신고결과받기

import java.util.*;

class Solution {
    public int[] solution(String[] id_list, String[] report, int k) {
        int answer[]=new int[id_list.length];
        HashMap<String, Integer> report_count = new HashMap<String, Integer>();
        HashSet<String> report_set = new HashSet<String>(Arrays.asList(report));
        
        for(String r: report_set){
            String key=r.split(" ")[1];
            report_count.put(key, report_count.getOrDefault(key,0)+1);
        }
        
        for(String r:report_set){
            String[] id=r.split(" ");
            if(report_count.get(id[1])>=k){
                int index = Arrays.asList(id_list).indexOf(id[0]);
                answer[index]+=1;
            }
      }
        return answer;
    }
}