9. 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?

 

class Solution {

    /**
     * @param Integer $x
     * @return Boolean
     */
    function isPalindrome($x) {
        if($x < 0){
            return false;
        }
        return strrev($x) == $x;
    }
}

For the followup

not converting to string? Create a  stack of integers instead (like a push down automata)

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