Leetcode 7 Reverse Integer

Reverse digits of an integer.

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

题目解析：

你要是敢用string解你就输了!!

一位一位运算吧骚年, 没啥好解释的, 注意overflow和负数情况就行~

public int reverse(int x) {
        int res = 0;
        while(x != 0){
            if(Math.abs(res) > 214748364)
                return 0;
            res = res * 10 + x % 10;
            x = x / 10;
        }
        if(x < 0)
            res = -res;
        return res;
}