0009-Palindrome-Number.py

#https://leetcode.com/problems/palindrome-number/

# Determine whether an integer is a palindrome. An integer is a palindrome when it reads the same backward as forward.

# Example 1:
# Input: 121
# Output: true

# Example 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?

# Method 1 (Meeting in the Middle and Comparing)

class Solution:
    def isPalindrome(self, x: int) -> bool:
        if (x<0 or (x%10 == 0 and x!=0)): #Negative or Ending with 0 but not 0 cases
            return False
        rev = 0
        while(x>rev):
            rev = (rev*10)+(x%10)
            x=x//10
        return rev==x or rev//10==x #Removing middle digit from a number with odd length using rev//10
        
# Method 2 (Reversing and Comparing)

class Solution:
    def isPalindrome(self, x: int) -> bool:
        if x < 0 or (x != 0 and not (x % 10)):
            return False
        integer, res = x, 0
        while integer > 0:
            res = res * 10 + (integer % 10)
            integer //= 10
            print(res)
        return res == x