8.7 8.8 Permutation

Following code can handle both unique or duplicates string!

    void getPermutation(string& s, int pos, vector<string>& res){
        if(pos == s.size()){
            res.push_back(s);
            return;
        }
        for (int i = pos; i<s.size(); ++i) {
            if(i!=pos && s[i] == s[pos]) continue;
            swap(s[i], s[pos]);
            getPermutation(s, pos+1, res);
        }
    }
    vector<string> permutation(string s){
        vector<string> res;
        getPermutation(s, 0, res);
        return res;
    }