Palindrome Number

Problem Link

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, its read -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.

Constraints:

-2³¹ <= x <= 2³¹ - 1

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

class Solution {
public:
    bool isPalindrome(int x) {
        // If x is negative or ends with 0 but is not 0, it cannot be a palindrome.
        if(x < 0 || (x % 10 == 0 && x != 0)) return false;

        int revercedNumber = 0;
        // Reverse half of the number to compare with the other half.
        while(x > revercedNumber) {
            // Add the last digit of x to revercedNumber.
            revercedNumber = revercedNumber * 10 + x % 10;
            x /= 10; // Remove the last digit from x.
        }

        // For numbers with an odd number of digits, we can get rid of the middle digit by reverced / 10.
        // For example, in the case of 12321, at the end of the loop we will have x = 12, revercedNumber = 123,
        // so we compare x with revercedNumber / 10.
        // This handles both even and odd length numbers by checking if the original number or its half-reversed version matches.
        return x == revercedNumber || x == revercedNumber / 10;
    }
};