Reverse Integer

 1 typedef long long  lld;
 2 lld mn=-((lld)1<<32-1);
 3 lld mx=(lld)1<<32-1;
 4 class Solution {
 5 public:
 6     int reverse(int x) {
 7         lld ans=0;
 8         int sign=0;
 9         if(x<0)
10         {
11             sign=1;
12             x=-x;
13         }
14         while(x)
15         {
16             ans=ans*10+x%10;
17             x/=10;
18         }
19         if(sign)
20             ans=-ans;
21         if(ans>mx||ans<mn)
22             ans=0;
23         return (int)ans;
24     }
25 };

 1 typedef long long   lld;
 2 lld mn=-(lld)1<<32;
 3 lld mx=(lld)1<<32-1;
 4 class Solution {
 5 public:
 6     int reverse(int x) {
 7         lld ans=0;
 8         while(x)
 9         {
10             ans=ans*10+x%10;
11             x/=10;
12         }
13         if(ans>mx||ans<mn)
14             ans=0;
15         return (int)ans;
16     }
17 };