reverse interger --- leetcode

Reverse digits of an integer.

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

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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.

Update (2014-11-10):

Test cases had been added to test the overflow behavior.

思路：第一，数字的最后一位是0的话，返回什么？maybe 10-》1，100-》1

  第二，反转后的数字如果溢出，应该返回什么，maybe 0

  反转就是简单的求余和除10

下面是代码：

class Solution {public:    int reverse(int x) {        int flag = 1;        if(x < 0)   flag = -1;        long n = abs(long(x));        long res = 0;        while(n)        {            res =res*10 + n%10;            n = n/10;        }        if(res > INT_MAX)   return 0;        return (int)res*flag;    }};