Palindrome Number

Idea

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

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.

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Idea

假设负数不是palindrome. 思路是截取最左边和最右边的两个digit比较，直到比较所有digit
每次比较之后用x = (x%d)/10 把左右两边的digit去掉

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Solution

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