9. Palindrome Number

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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?

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class Solution {
public:
    bool isPalindrome(int n) {
        if(n < 0 || (n % 10 == 0 && n != 0)) {
            return false;
        }
        int revnum = 0;
        while(n > revnum) {
            revnum = (revnum * 10) + (n % 10);
            n = n / 10;
        }
        return n == revnum || n == revnum / 10;
        
    }
};