345. Reverse Vowels of a String

📋 Đề Bài

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.

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.

💻 Lời Giải

Python 0345-reverse-vowels-of-a-string.py

class Solution:
    def reverseVowels(self, s: str) -> str:
        vowels = set('aeiouAEIOU')
        n = len(s)
        s = list(s)
        i, j = 0, n - 1
        
        while i < j:
            if s[i] in vowels and s[j] in vowels:
                s[i], s[j] = s[j], s[i]
                i += 1
                j -= 1
            elif s[i] not in vowels:
                i += 1
            else:
                j -= 1
                
        return ''.join(s)