Palindrome Number

题目：

Determine whether an integer is a palindrome. Do this without extra space.

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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.

分析： 数字x对称,那么x的前半部分和后半部分的反转相同，只需求出一半即可，不需考虑溢出问题。

代码：

class Solution {public:    bool isPalindrome(int x) {        int res=0;        if(x<0) return false;        if(x==0) return true;        if(x%10==0) return false;                while(x>res)        {            res=res*10;            res+=(x%10);            x/=10;        }        return (x==res||(res/10==x));    }};