09.回文数

判断一个整数是否回文数。当一个整数正序或倒序读都是一样的，那么它是回文数。

####例子1：

Input: 121
Output: true

####例子2:

Input: -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

####例子3:

Input: 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

####进阶：不将整数转化为字符串解决这个问题。

####解法：和翻转整数一样的思路，翻转后对比翻转前后是否相等。

/**
 * @param {number} x
 * @return {boolean}
 */
var isPalindrome = function(x) {
    let init = x;
    let res = 0;
    while (x > 0) {
        res = res * 10 + x % 10;
        x = Math.floor(x / 10);
    }
    return init === res;
};