[LeetCode] 7. Reverse Integer

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.

题意：翻转一个int数，注意两点，一是越界，而是0的问题

class Solution {
    public int reverse(int x) {
        if (x == -2147483648)
            return 0;
        boolean flag = false;
        if (x < 0)
            flag = true;
        x = Math.abs(x);
        long res = 0;
        while (x != 0) {
            res = res*10 + x%10;
            x /= 10;
            if (res > Integer.MAX_VALUE) {
                res = 0;
                return 0;
            }
        }
        if (flag)
            return (int)-res;
        return (int)res;
    }
}