LeetCode Palindrome Number

题目来源：https://leetcode.com/problems/palindrome-number/

Determine whether an integer is a palindrome. Do this without extra space.click to show spoilers.Some hints:Could negative integers be palindromes? (ie, -1)If you are thinking of converting the integer to string, note the restriction of using extra space.You could also try reversing an integer. However, if you have solved the problem "Reverse Integer", you know that the reversed integer might overflow. How would you handle such case?There is a more generic way of solving this problem.

题目要求不能使用额外空间，那就只能使用log10求出数字长度，然后分别从高位和低位开始，依次判断是否想等了。

题目需要注意以下几点：

1. 负数直接返回false;

2. 0应该返回true;

代码如下：

class Solution {
public:
bool isPalindrome(int x) {
if (x < 0)
return false;
int len = log10(x);
for (int i = 0; i < (len / 2 + 1); i++)
{
if ((x / (int)pow(10, i)) % 10 != (x / (int)pow(10, len - i)) % 10)
return false;
}
return true;
}
};