editorial version

_srm317.cc

class PalindromicNumbers {
    public:
    int countPalNums(int lower, int upper) {
        string s,t;
        int cnt=0;
        for(int even=1;even<10000;even++){
          t = s = to_string(even);
          reverse(s.begin(), s.end());
          if(lower<=stoi(t+s) && stoi(t+s)<=upper) cnt++;
        }
        for(int odd=1;odd<100000;odd++){
          t = s = to_string(odd);
          reverse(s.begin(), s.end());
          t.resize(t.size()-1);
          if(lower<=stoi(t+s) && stoi(t+s)<=upper) cnt++;
        }
        return cnt;
    }
};