1935. Maximum Number of Words You Can Type

There is a malfunctioning keyboard where some letter keys do not work. All other keys on the keyboard work properly.

Given a string text of words separated by a single space (no leading or trailing spaces) and a string brokenLetters of all distinct letter keys that are broken, return the number of words in text you can fully type using this keyboard.

class Solution {
public:
    int canBeTypedWords(string text, string brokenLetters) {
        istringstream iss(text);
        vector<string> filter;
        string token;
        while (getline(iss, token, ' ')) if (!token.empty()) filter.push_back(token);
        
        for(auto& ch : brokenLetters) {
            vector<string> nfilter;
            for(auto& f : filter) if(!count(f.begin(), f.end(), ch)) nfilter.push_back(f);
            swap(filter, nfilter);
        }
        
        return filter.size();
    }
};