Reverse Integer

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

方法：考虑溢出情况，并与INT_MAX和INT_MIN比较

class Solution {
public:
    int reverse(int x) {
        long long res = 0;
        while(x){
            res = res*10 + x%10;
            x/=10;
        }
        return (res<INT_MIN||res>INT_MAX)?0:res;
    }
};