Among all contiguous substrings of s with exactly k characters, return the largest number of vowels in any one substring. The vowels are a, e, i, o, and u.
Example 1:
Input: s = "buaex"
k = 3
Output: 3Explanation: The substring "uae" contains three vowels. A substring of length 3 cannot contain more than three, so this is optimal.
Example 2:
Input: s = "rhythms"
k = 4
Output: 0Explanation: None of these letters is a vowel. Every length-4 substring contains zero vowels.
Example 3:
Input: s = "abaca"
k = 5
Output: 3Explanation: The only length-5 substring is the entire string "abaca". Its three occurrences of a are vowels.
Constraints:
1 <= s.length <= 100000scontains only lowercase English letters.1 <= k <= s.length