leetcode007. Reverse Integer 

 1 /* a good way to predict overflow
 2  * each time *10 must predict int overflow
 3  * not only the last time to predict which will be wrong.
 4  */
 5 class Solution {
 6 public:
 7     int reverse(int x) {
 8         if(x==0)return x;
 9         int tag=0;
10         long int re=0;
11         if(x<0)
12         {
13             tag=1;
14             x=-x;
15         }
16         while(x)
17         {
18             int tmp=re*10+x%10;
19             if((tmp-x%10)/10!=re)return 0;
20             re=tmp;
21             x=x/10;
22         }
23         if(tag)re=-re;
24         return re;
25     }
26 };
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posted @ 2016-09-07 22:43  zeroArn  阅读(108)  评论(0)    收藏  举报