5417_max_vowels.py

'''
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, 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.
Example 4:
Input: s = "rhythms", k = 4
Output: 0
Explanation: We can see that s doesn't have any vowel letters.
Example 5:
Input: s = "tryhard", k = 4
Output: 1

Constraints:
1 <= s.length <= 10^5
s consists of lowercase English letters.
1 <= k <= s.length
'''
class Solution:
    def maxVowels(self, s: str, k: int) -> int:
        vowels = {'a', 'e', 'i', 'o', 'u'}
        i = 0
        res = 0
        count_v = 0
        for ch in s[:k]:
            if ch in vowels:
                count_v += 1
        res = max(count_v, res)
        for j in range(k, len(s)):
            if s[j] in vowels:
                count_v += 1
            if s[j - k] in vowels:
                count_v -= 1
            res = max(count_v, res)
        return res

sol = Solution()
s = "leetcode"
k = 3
res = sol.maxVowels(s, k)
print(res)