[LeetCode]Palindrome Number@python

最新推荐文章于 2022-04-02 15:31:39 发布

原创最新推荐文章于 2022-04-02 15:31:39 发布 · 148 阅读

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本文介绍了一种在不使用额外空间的情况下判断整数是否为回文的方法。通过对比整数的最高位和最低位来逐步验证其回文特性，特别讨论了负数情况及整数反转可能导致的溢出问题。

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.

是不允许有额外空间的，所以不能转成字符串，这里可以取它最高位和最低位比较是否相等。向中间缩进。

class Solution(object):
    def isPalindrome(self, x):
        """
        :type x: int
        :rtype: bool
        """
        if x < 0:
            return False
        div = 1
        while x/div >= 10:
            div = div*10
        
        while x:
            left = x/div
            right = x%10
            
            if left != right:
                return False
            
            x = (x % div) / 10 #取余是删除最高位，取模是删除最低位 
            div = div/100
        return True