lc 166. fraction to recurring decimal

class Solution {
public:
    string fractionToDecimal(int numerator, int denominator) {
        map<int, int> ndMap;
        string res = "";
        if(numerator < 0 ^ denominator < 0)
          res += "-";
        if(numerator == 0)
            res = "";
        long num = abs((long)numerator);
        long den = abs((long)denominator);
        long rem = num % den;
        string decRes = "";
        while((rem != 0) && ndMap.find(rem) == ndMap.end()){
            ndMap[rem] = decRes.length();
            rem *= 10;
            decRes += to_string(rem / den);
            rem %= den;
        }
        cout << decRes << endl;
        if(rem == 0){
            res += num % den == 0 ?  to_string(num / den) : to_string(num / den) + "." + decRes;
        }else
            res += to_string(num / den) + "." + decRes.substr(0, ndMap[rem]) + "(" + decRes.substr(ndMap[rem]) + ")";
        return res;
    }
};

string fractionToDecimal(int numr, int denr)
        {
            string res; // Initialize result

            // Create a map to store already seen remainders
            // remainder is used as key and its position in
            // result is stored as value. Note that we need
            // position for cases like 1/6.  In this case,
            // the recurring sequence doesn't start from first
            // remainder.
            map<int, int> mp;
            mp.clear();

            // Find first remainder
            int rem = numr%denr;

            // Keep finding remainder until either remainder
            // becomes 0 or repeats
            while ( (rem!=0) && (mp.find(rem) == mp.end()) )
            {
                // Store this remainder
                mp[rem] = res.length();

                // Multiply remainder with 10
                rem = rem*10;

                // Append rem / denr to result
                int res_part = rem / denr;
                res += to_string(res_part);

                // Update remainder
                rem = rem % denr;
            }

            return (rem == 0)? "" : res.substr(mp[rem]);
        }