【LeetCode with Python】 Palindrome Number

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本文详细介绍了如何在不使用额外空间的情况下判断整数是否为回文数，提供了代码实现和解题思路。

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原题页面： https://oj.leetcode.com/problems/palindrome-number/
题目类型：
难度评价：★
本文地址： http://blog.youkuaiyun.com/nerv3x3/article/details/37335981

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.

class Solution:

    # @return a boolean
    def isPalindrome(self, x):
        if x < 0:
            return False
        if x < 10:
            return True
        div = 1
        val = x
        while True:
            val = int(val / 10)
            if val > 0:
                div *= 10
            else:
                break

        while div > 0:
            left = int(x / div)
            right = int(x % 10)
            if left != right:
                return False
            x = x % div
            x = x / 10
            div = int(div / 100)
        return True