완주하지 못한 선수(문제37)

import java.util.*;
 
class Solution {
    public String solution(String[] participants, String[] completions) {
        Map<String, Integer> map = new HashMap<>();
        for(String p : participants){
            map.putIfAbsent(p, 0);
            map.put(p, map.get(p) + 1);
        }
        
        for(String c : completions){
            if(map.get(c) == 0) return c;
            map.put(c, map.get(c) - 1);
        }
        
        for(Map.Entry<String, Integer> entrySet : map.entrySet()){
            if(entrySet.getValue() != 0) return entrySet.getKey();
        }
        return "";
    }
}

import java.util.HashMap;
import java.util.Map;

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

        for (String name : participant) {
            count.putIfAbsent(name, 0);
            count.put(name, count.get(name) + 1);
        }

        for (String name : completion) {
            int v = count.get(name) - 1;
            count.put(name, v);
            if (v == 0) count.remove(name);
        }

        return count.keySet().iterator().next();//굳
    }
}