Leetcode(9) Palindrome Number

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Description:

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.

解法

主要掌握从一个数中取一部分的方法： 求除数的方法

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while(x/div>=10):
    div*=10;

取最右边的数

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x = x % 10

取最左边的数

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x = x/div;

取左部分

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x = x /10

取右部分

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x = x % div

我的代码

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import math;
class Solution:
    def isPalindrome(self, x):
        """
        :type x: int
        :rtype: bool
        """
        div = 1;
        if(x<0):
            return False;
        while(x/div>=10):
            div*=10;
        while(x>0):
            right = x%10;
            left = x/div;
            left = math.floor(left);
            if(right != left):
                return False;
            x = (x%div)/10;
            x = math.floor(x);
            div/=100;
            div = math.floor(div);
        return True;