[프로그래머스] 완주하지 못한 선수

https://programmers.co.kr/learn/courses/30/lessons/42576/solution_groups?language=java

프로그래머스

import java.util.HashMap;

class Solution {
    public String solution(String[] participant, String[] completion) {
        String answer = "";
        HashMap<String, Integer> hash = new HashMap<String, Integer>();

        for (String s : completion) {
            hash.put(s, hash.getOrDefault(s, 0) + 1);
        }

        for (String s : participant) {
            if (hash.get(s) == null || hash.get(s) == 0) {
                answer = s;
                break;
            }
            hash.put(s, hash.get(s) - 1);
        }

        return answer;
    }
}