9. Palindrome Number Leetcode Python

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.

这题的做法是依次取出第一位和最后一位进行比较。

class Solution:
    # @return a boolean
    def isPalindrome(self, x):
        if x<0:
            return False
        div=1
        while div<=x/10:
            div*=10
        while x>0:
            if x/div!=x%10:
                return False
            x=(x%div)/10
            div/=100
        return True