✔ HashMapimport java.util.*; class Solution { public String solution(String[] participant, String[] completion) { String answer = ""; Map map = new HashMap(); for (String p : participant) { map.put(p, map.getOrDefault(p, 0) +1); } for (String c : completion){ map.put(c, map.get(c) -1); } for (String key : map.keySet()){ if(map.get(key) != 0){ answer = key; break; } } return answer; } }1. Map을 사용..
