김지수

public String solution(String[] participant, String[] completion) { Map<String, Integer> map = new HashMap<>(); String ans = ""; for (String key : participant) { // if (map.containsKey(key)) map.put(key, map.get(key) + 1); // else map.put(key, 1); map.put(key, map.getOrDefault(key, 0) + 1); } for (String key : completion) { map.put(key, map.get(key) - 1); } for (String key : participant) { if (map.get(key) != 0) ans = key; } return ans; }