Palindrome Number

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.

思路：这道题判断一个整数是不是回文数，通常做法就是将n模10取余存入数组中，然后除10进入下一循环。然后从这个数组出发，判断头尾是否相同。但是这题强调不使用额外的内存空间，所以应该这样处理，设一变量result，每次循环这样处理result=result*10+base%10;base/=10;注意这题一定要使用一个赋上x的临时变量base，否者我们就会改变x的值，不能进行下面的判断。注意负数不可能是回文数，也就是只针对非负数。

class Solution {

public:

    bool isPalindrome(int x) {

        if(x<0)

        {

            return false;

        }

        int result=0;

        int base=x;

        while(base!=0)

        {

            result=result*10+base%10;

            base/=10;

        }

        if(result!=x)

            return false;

        return true;

    }

};