Leetcode: Reverse Integer

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?

Throw an exception? Good, but what if throwing an exception is not an option? You would then have to re-design the function (ie, add an extra parameter).

除以10，存结果和余数，并计算，直到结果为0。一下代码没有考虑溢出的情况，如果溢出，得到的结果会和输入值符号相反，以此判断是否溢出，用另外一个参数来存最后一位值。

public class Solution {    public int reverse(int x) {        int res = 0;        while (x != 0) {            res = res * 10 + x % 10;            x = x / 10;        }                return res;    }}