【leetcode 简单】 第八十三题 反转字符串中的元音字母

class Solution:
    def reverseVowels(self, s):
        """
        :type s: str
        :rtype: str
        """
        start = 0
        end = len(s)-1
        if end <= start:
            return s
        tmp = list(s)
        limit = 'aeiouAEIOU'
        while start < end:
            if tmp[start] not in limit:
                start += 1
            elif tmp[end] not in limit:
                end -= 1
            else:
                tmp[start],tmp[end]=tmp[end],tmp[start]
                start += 1
                end -= 1
        return ''.join(tmp)