leetcode---Reverse Integer

Reverse digits of an integer.

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

class Solution {public:    int reverse(int x) {        if(x > pow(2, 31)-1 || x < -1 * pow(2, 31))  //溢出            return 0;        if((int)(x / pow(10, 9)) != 0)  //如果它有10位数字            if(x % 10 > 2 || x % 10 < -2)  //最低位的绝对值超过2                return 0;        int n = x;        int result = 0;        int flag;        if(x > 0)            flag = 1;        else            flag = -1;        while(n)        {            result = result * 10 + n % 10;            if(flag * result < 0) //溢出                return 0;            n /= 10;        }        return result;    }};