简单的题目反而坑点多啊,用long long防止溢出
class Solution {
public:
typedef long long ll;
int reverse(int x) {
int f=1;
ll xx=x;
if(x<0) f=-1,xx=-xx;
ll ans=0;
while(xx) ans=ans*10+xx%10,xx/=10;
if(ans>(1LL<<31)-1||ans<-(1LL<<31)) ans=0;
return (int)ans*f;
}
};