Reverse Vowels of a String

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".

Two Pointers

class Solution(object):
    def reverseVowels(self, s):
        """
        :type s: str
        :rtype: str
        """
        s = list(s)
        start = 0
        end = len(s)-1
        vowels = 'aeiouAEIOU'
        while start < end:
            # bug: while s[start] not in vowels:
            while s[start] not in vowels and start < end:
                start += 1
            # bug: while s[end] not in vowels:
            while s[end] not in vowels and start < end:
                end -= 1
            s[start], s[end] = s[end], s[start]
            start += 1
            end -= 1
        return ''.join(s)