345\. Reverse Vowels of a String

Easy

Given a string `s`, reverse only all the vowels in the string and return it.

The vowels are `'a'`, `'e'`, `'i'`, `'o'`, and `'u'`, and they can appear in both cases.

**Example 1:**

**Input:** s = "hello"

**Output:** "holle"

**Example 2:**

**Input:** s = "leetcode"

**Output:** "leotcede"

**Constraints:**

*   1 <= s.length <= 3 * 105
*   `s` consist of **printable ASCII** characters.