Reverse Vowels of a String

Problem Statement

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 lower and upper cases, more than once.

Leetcode link

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.

Code

Python Code

class Solution(object):
    def reverseVowels(self, s):
        """
        :type s: str
        :rtype: str
        """

        vowels = ['a', 'e', 'i', 'o', 'u']

        s = list(s)
        i = 0
        j = len(s) - 1
        while i < j:
            while i < j and s[i].lower() not in vowels:
                i += 1
            while i < j and s[j].lower() not in vowels:
                j -= 1

            if s[i].lower() in vowels and s[j].lower() in vowels:
                temp = s[i]
                s[i] = s[j]
                s[j] = temp

            i += 1
            j -= 1

        return "".join(s)