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Palindrome Number without converting the integer to a string

Chapters

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 a palindrome while 123 is not.

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?

Table of Contents
1. Solution 1:
2. Solution 2:

Solution 1:

return False if x < 0 else x == int(str(x)[::-1])

Solution 2:

class Solution:
    def isPalindrome(self, x):
        """
        :type x: int
        :rtype: bool
        """
        if x < 0:
            return False
        str_1 = str(abs(x))
        str_2 = str_1[::-1]
        if str_1 == str_2:
            return True
        else:
            return False