一、题目描述
https://leetcode.com/problems/palindrome-number/description/
二、题目分析Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.(确定整数是否是回文。 一个整数是一个回文,当它向后读取时与向前一样。)
Example 1:
Input: 121 Output: trueExample 2:
Input: -121 Output: false Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.Example 3:
Input: 10 Output: false Explanation: Reads 01 from right to left. Therefore it is not a palindrome.Follow up:
Coud you solve it without converting the integer to a string?
不能使用int转成string(return str(x)[::-1]==str(x)),暴风哭泣
分析:负数都不是回数,于是只考虑正数,正数求倒数,判断是否是回数,不使用int to string的方法求一个数的倒数的方法如下:
三、代码实现
class Solution(object): def isPalindrome(self, x): """ :type x: int :rtype: bool """ y=0 #y是倒数 temp=x if x<0:return False while temp>0: y=y*10+temp%10 temp/=10 return y==x