> For the complete documentation index, see [llms.txt](https://garychang.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://garychang.gitbook.io/leetcode/9.-palindrome-number.md).

# 9. Palindrome Number

<https://leetcode.com/problems/palindrome-number/description/>

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?

**Solution1:**

```
class Solution(object):
    def isPalindrome(self, x):
        """
        :type x: int
        :rtype: bool
        """
        if x < 0: return False
        else:
            s = str(x)
            l = len(s)
            for ss in s:
                if ss != s[l-1]:
                    return False
                l -= 1
        return True
```

**Solution2:**

```
class Solution(object):
    def isPalindrome(self, x):
        """
        :type x: int
        :rtype: bool
        """
        if (x < 0) or (x != 0 and x%10 == 0): return False
        y = 0
        while x > y:
            y = y*10 + x%10
            x = x/10
        if (x == y) or (y/10 == x): return True
        else: return False
```