LeetCode
Leetcode 9 Palindrome Number - Easy
9. Palindrome Number - Easy
Given an integer x, return true if x is palindrome integer.
An integer is a palindrome when it reads the same backward as forward. For example, 121 is palindrome while 123 is not.
Examples:
Input: x = 121
Output: true
Input: x = -121
Output: false
Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.
Input: x = 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
Solution :
Math, Space O(1), Time O(n), n is the number of digits in x.
class Solution:
def isPalindrome(self, x: int) -> bool:
if x < 0:
return False
origin = x
reverse = 0
while x != 0:
mod = x % 10
x = x // 10
reverse = reverse * 10 + mod
if origin == reverse:
return True