0009: Palindrome Number

Problem Statement

Given an integer x, return true if x is a palindrome, and false otherwise.

Example 1:

Input: x = 121
Output: true
Explanation: 121 reads as 121 from left to right and from right to left.

Example 2:

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.

Example 3:

Input: x = 10
Output: false
Explanation: Reads 01 from right to left. Therefore it is not a palindrome.

Constraints:

  • -231 <= x <= 231 - 1

Follow up: Could you solve it without converting the integer to a string?

Code Solution

class Solution:
    def isPalindrome(self, x: int) -> bool:
        s = str(x)
        
        lx = 0
        rx = len(s) - 1
        while lx < rx and s[lx] == s[rx]:
            lx = lx + 1
            rx = rx - 1
        
        return lx >= rx