Largest Number

class Solution {
public:
        string largestNumber(vector<int> &num) {

            int n = num.size();
            vector<string> numstrs(n);

            for(int i = 0; i < n; i++)
            {
                numstrs[i] = to_string(num[i]); // to_string() is standard lib func
            }

            sort(numstrs.begin(), numstrs.end(), myCompare);

            if (numstrs[n-1] == "0")
            {
                return "0";
            }

            string res;
            for(int i = n-1; i >= 0; i--)
            {
                res += numstrs[i];
            }

            return res;
        }

        static bool myCompare (string str1, string str2)
        {
            return (str1 + str2) < (str2 + str1);
        }
};