此题需要注意的地方是处理数字反转后溢出的情况
class Solution {
public:
int reverse(int x) {
if(x==0)
return x;
int res = 0;
int sign = 1;
if(x<0)
{
sign = -1;
x = abs(x);
}
while(x!=0)
{
if(res>(INT_MAX-x%10)/10)
return 0;
int digit = x%10;
res = res*10 + digit;
x = x/10;
}
return (sign==-1)? -res:res;
}
};