Atcoder解いてみた ABC 071 B - Not Found

ABC 071 B - Not Found 解いてみた

問題はこちら

回答

#include <iostream>
#include <string>
#include <map>
using namespace std;

int main() {
    string S;
    cin >> S;

    map<char, char> sMap;
    string refStr = "abcdefghijklmnopqrstuvwxyz";

    for (auto it = S.begin(); it != S.end(); ++it) {
        sMap[*it];
    }

    if (sMap.size() == 26) {
        std::cout << "None" << std::endl;
    }

    for (auto it = refStr.begin(); it != refStr.end(); ++it) {
        if(sMap.find(*it) == sMap.end()){
            std::cout << *it << std::endl;
            break;
        }
    }

    return 0;
}