7. Reverse Integer. 整数int

Given a 32-bit signed integer, reverse digits of an integer.

Example 1:

Input: 123
Output: 321
Example 2:

Input: -123
Output: -321
Example 3:

Input: 120
Output: 21
Note:
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231,  231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/reverse-integer

1.整数边界
int 为32位
int max = 0x7fffffff;
int min = 0x80000000;

class Solution {
public:
    int reverse(int x) {
        int max = 0x7fffffff;
        int min = 0x80000000;
        long ans = 0;

        while (x){
            ans = ans * 10 + x % 10;
            if (ans > max || ans < min) return 0;
            x /= 10;
        }

        return ans;
    }
};