Reverse Vowels of a String

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Given a string s, reverse only all the vowels in the string and return it.
给定一个字符串，只反转字符串 s 中的所有元音并返回它。

The vowels are 'a', 'e', 'i', 'o', and 'u', and they can appear in both lower and upper cases, more than once.
元音是 'a' 、、 'e' 'i' 和 'o' 'u' ，它们可以多次出现在小写和大写中。

Example 1: 示例 1：

Input: s = "hello" Output: "holle"

Example 2: 示例 2：

Input: s = "leetcode" Output: "leotcede"

Constraints: 约束：

1 <= s.length <= 3 * 105
s consist of printable ASCII characters.
s 由可打印的 ASCII 字符组成。

class Solution(object):
    def reverseVowels(self, s):
        """
        :type s: str
        :rtype: str
        """
        vowels = "aeiouAEIOU"
        s = list(s)
        left = 0
        right = len(s) - 1

        while left < right:
            if s[left] in vowels and s[right] in vowels:
                s[left], s[right] = s[right], s[left]
                left += 1
                right -= 1
            elif s[left] not in vowels:
                left += 1
            elif s[right] not in vowels:
                right -= 1

        return "".join(s)

    def test(self):
        s = "hello"
        expected = "holle"
        actual = self.reverseVowels(s)
        if actual == expected:
            print("Test passed.")
        else:
            print("Test failed. %s != %s" % (actual, expected))

if __name__ == "__main__":
    Solution().test()