string reverseWords(string s) {
       int n = s.size();
       std::string reverse_string = "";
       for ( int i = n-1 ; i > -1; --i ){
        if (s[i] == ' '){
            continue;
        }
        int count = 0;
        while ( i > -1 && s[i] != ' '){
            --i; count++;
        }
        if (reverse_string != ""){
            reverse_string.append(" ");
        }
        reverse_string.append(s.substr(i+1,count));
       }
       return reverse_string; 
    }