# 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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