> For the complete documentation index, see [llms.txt](https://cmmobile.gitbook.io/cmmobilebook/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cmmobile.gitbook.io/cmmobilebook/cheng-shi-lian-xi-ti/shu-zi-cao-zuo/he-fa-hui-wen-1-valid-palindrome.md).

# 合法回文-1 Valid Palindrome

Easy

[回文題目](https://leetcode.com/problems/valid-palindrome/)

{% embed url="<https://leetcode.com/problems/valid-palindrome/>" %}

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

**Note:** For the purpose of this problem, we define empty string as valid palindrome.

**Example 1:**

```
Input: "A man, a plan, a canal: Panama"
Output: true
```

**Example 2:**

```
Input: "race a car"
Output: false
```