0007.cpp

class Solution {
  public:
    int reverse(int x) {
        if (x == INT_MIN || x == INT_MAX) return 0;

        bool neg = false;
        unsigned long res = 0;

        if (x < 0) {
            neg = true;
            x = -x;
        }

        do {
            res = res * 10 + x % 10;
        } while ((x /= 10) > 0);

        if (res > INT_MAX) return 0;
        return !neg ? res : -res;
    }
};