1456. Maximum Number of Vowels in a Substring of Given Length Medium

link to leetcode

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

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 <= 105

s consists of lowercase English letters.

1 <= k <= s.length

Details

Solution

class Solution:
    def maxVowels(self, s: str, k: int) - int:
        ans = vowel = 0
        for i, c in enumerate(s):
            if c in "aeiou":
                vowel += 1
            if i < k - 1:  
                continue
            ans = max(ans, vowel)
            if s[i - k + 1] in "aeiou":
                vowel -= 1
        return ans