leetcode--7. Reverse Integer

Reverse digits of an integer.

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

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Note:

The input is assumed to be a 32-bit signed integer. Your function should return 0 when the reversed integer overflows.

水题，只是要注意判断是否溢出，一开始忘记判断了

class Solution {
public:
    int reverse(int x) {
        int tmp = x, ret = 0;
        while(tmp) {
            int oldnum = ret;
            ret = ret * 10 + tmp % 10;
            if((ret - tmp % 10) / 10 != oldnum) return 0;
            tmp /= 10;
        }
        return ret;
    }
};