Solution.cpp

class Solution {
public:
    int countConsistentStrings(string allowed, vector<string>& words) {
        bitset<26> s;
        for (auto& c : allowed) s[c - 'a'] = 1;
        int ans = 0;
        auto check = [&](string& w) {
            for (auto& c : w)
                if (!s[c - 'a']) return false;
            return true;
        };
        for (auto& w : words) ans += check(w);
        return ans;
    }
};