[프로그래머스]완주하지 못한 선수

#include <string>
#include <vector>
#include <algorithm>
 
using namespace std;
 
string solution(vector<string> participant, vector<string> completion) {
    vector<int> val;
    string answer = "";
    sort(participant.begin(), participant.end());
    sort(completion.begin(), completion.end());
    int count1 = 1, count2 = 1;
    int j = 0, i = 0;
    while(true) {
        count1 = 1, count2 = 1;
        while(i < participant.size() - 1 && participant[i] == participant[i + 1]) {
            count1++;
            i++;
        }
        while(j < completion.size() - 1 && completion[j] == completion[j + 1]){
            count2++;
            j++;
        }
        if(participant[i] != completion[j] || count1 != count2) {
            answer = participant[i];
            return answer;
        }
        i++, j++;
    }
    
   return answer;
}