https://programmers.co.kr/learn/courses/30/lessons/12899

char country[3] = { '4', '1', '2' };

string solution(int n) {
    string answer = "";
    while(n > 0){
        int remain = n % 3;
        n /= 3;
        if(remain == 0){
            n -= 1;
        }
        answer += country[remain];
    }
    reverse(answer.begin(), answer.end());
    return answer;
}