LeetCode之7,数论部分的ReverseInteger

（PS：这两天寒假在家，除了适当的家务要做之外，感觉学习反倒成了附属品。）

数论的题不难，但是考察点在边边角角上，比如反转时是否溢出等，尤其是负值变正值时。

reverse integer原题如下：

Reverse digits of an integer.

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

重点是下面：

Have you thought about this?

Here are some good questions to ask before coding. Bonus points for you if you have already thought through this!

If the integer's last digit is 0, what should the output be? ie, cases such as 10, 100.

Did you notice that the reversed integer might overflow? Assume the input is a 32-bit integer, then the reverse of 1000000003 overflows. How should you handle such cases?

For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

class Solution {public:    int reverse(int x) {        long long ans=0;        const int maxint=0x7fffffff;        const int minint=0x80000000;        while(x!=0)        {            ans=ans*10+(x%10);            x/=10;        }        if(ans<minint||ans>maxint)        {            return 0;        }        return ans;    }};