Palindrome Number

题目描述

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

解题方法

extra space

变换成array, 然后方便的得到左右两边的digit

no extra space

因为不能用额外空间，所以不能转化成array再做

尝试用最naive的方法去做， 用数学方法不断得到最大的digit和最小的digit，比较之后将它们去掉，除数的大小也要调整

Solution

class Solution(object):
    def isPalindrome(self, x):
        """
        :type x: int
        :rtype: bool
        """
        if x < 0:
            return False
        largeD = 1
        if x < 10:
            return True

        while x >= largeD:
            largeD *= 10
        largeD /= 10

        while largeD > 1:
            firstDigit = x / largeD
            lastDigit = x % 10
            if firstDigit != lastDigit:
                return False
            x = x % largeD
            x = x / 10
            largeD /= 100

        return True

Reference