Python [Leetcode 345]Reverse Vowels of a String

题目描述：

Write a function that takes a string as input and reverse only the vowels of a string.

Example 1:
Given s = "hello", return "holle".

Example 2:
Given s = "leetcode", return "leotcede".

Note:
The vowels does not include the letter "y".

解题思路：

设置两个指针，分别从前往后与从后往前移动

代码如下：

class Solution(object):
    def reverseVowels(self, s):
        """
        :type s: str
        :rtype: str
        """
        vowels = set(list('aeiouAEIOU'))
        s = list(s)
        start = 0
        end = len(s) - 1

        while start <= end:
            if s[start] in vowels and s[end] in vowels :
                s[start], s[end] = s[end], s[start]
                start += 1
                end -= 1
            else:
                if s[start] not in vowels:
                    start += 1
                if s[end] not in vowels:
                    end -= 1

        return ''.join(s)