"""
Given a string s and an integer k, return the maximum number of vowel letters in any substring of s with length k.

Vowel letters in English are 'a', 'e', 'i', 'o', and 'u'.

Example 1:
Input: s = "abciiidef", k = 3
Output: 3
Explanation: The substring "iii" contains 3 vowel letters.

Example 2:
Input: s = "aeiou", k = 2
Output: 2
Explanation: Any substring of length 2 contains 2 vowels.

Example 3:
Input: s = "leetcode", k = 3
Output: 2
Explanation: "lee", "eet" and "ode" contain 2 vowels.


Constraints:
1 <= s.length <= 10^5
s consists of lowercase English letters.
1 <= k <= s.length
"""

class MaximumNumberOfVowelsInaSubstringOfGivenLength:
    def maxVowels(self, s: str, k: int) -> int:
        vowels = "aeiou"
        res = cnt = 0
        for i, c in enumerate(s):
            if c in vowels:
                cnt += 1
            if i >= k and s[i - k] in vowels:
                cnt -= 1
            res = max(res, cnt)
        return res