자바 - 완주하지 못한 선수

문제 :

풀이 :

import java.util.*;

class Solution {
    public String solution(String[] participant, String[] completion) {
        String answer =""; 
        HashMap<String, Integer> hm = new HashMap<>(); 
        for(String player : participant) hm.put(player, hm.getOrDefault(player, 0) + 1); 
        for(String player : completion) hm.put(player, hm.get(player) -1); 
        for(String key : hm.keySet()) {
            if(hm.get(key) != 0) {
                answer = key; System.out.println(answer); 
                break; 
            } 
        } 
        return answer;

    }
}