leetcode: 242. valid anagram

class  {
public:
    bool isAnagram(string s, string t) {
        unordered_map<char, int> mapDic;
        for (auto i: s) {
            if (mapDic.find(i) == mapDic.end()) {
                mapDic[i] = 1;
            } else {
                mapDic[i] += 1;
            }
        }

        for (auto i: t) {
            if (mapDic.find(i) == mapDic.end()) {
                return false;
            } else {
                if (--mapDic[i] == 0)
                    mapDic.erase(mapDic.find(i));
            }
        }

        if (mapDic.empty() == true) {
            return true;
        }

        return false;
    }
};