string largestNumber(vector<int>& nums) {

         vector<string> s;

         for( auto n : nums){

             s.push_back(to_string(n));

         }

         sort( begin(s), end(s) , [](string &s1 , string s2){ return s1 + s2 < s2 + s1;});

         string res ;

         for(vector<string>::reverse_iterator it = s.rbegin() ; it != s.rend(); ++it){

             res += *it;

         }

         if( res.front() == '')

             res = "";

         return res;

     }