Is Maximum Number of Vowels in a Substring of Given Length easy or hard?

The problem is generally classified as Medium. The implementation is straightforward once you recognize the sliding window pattern, but candidates who try brute force substring checks may end up with inefficient O(n * k) solutions.

Maximum Number of Vowels in a Substring of Given Length Python/Java solution

In Python or Java, implement a sliding window that iterates through the string once. Maintain a vowel count for the current window and update it when the window shifts. This approach works in O(n) time and O(1) space and is commonly used in competitive programming and interviews.

What is the best approach for Maximum Number of Vowels in a Substring of Given Length?

The sliding window approach is the best solution. It maintains a running count of vowels while moving a fixed-size window of length k across the string. Each step updates the count by removing the outgoing character and adding the incoming one, resulting in O(n) time and O(1) space.

Is Maximum Number of Vowels in a Substring of Given Length asked at Google/Amazon/Meta?

Sliding window string problems like this frequently appear in interviews at companies such as Amazon, Google, and Meta. The problem tests pattern recognition, efficient substring processing, and understanding of fixed-length window optimization.

What data structure is used in Maximum Number of Vowels in a Substring of Given Length?

The problem mainly relies on the sliding window technique and simple character checks. Many implementations use a set or conditional checks to determine if a character is a vowel, while maintaining a running counter for the window.

What is the time complexity of Maximum Number of Vowels in a Substring of Given Length?

The optimal sliding window solution runs in O(n) time where n is the length of the string, because each character is processed once as the window moves forward. Space complexity is O(1) since only counters and a small vowel check structure are required.

Description Hints 2 Solution Video 7:58

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

Q: How to solve Maximum Number of Vowels in a Substring of Given Length in O(n)?

Use a sliding window of size k. Count vowels in the first k characters, then move the window one step at a time. Decrease the count if the left character was a vowel and increase it if the new right character is a vowel. Track the maximum value during traversal.

Medium63.0% acceptance6 companies

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 <= 10⁵
s consists of lowercase English letters.
1 <= k <= s.length

Asked at 6 companies

Amazon Meta Microsoft

TCS

Google Bloomberg

Topics

Sliding Window String

Hints open one at a time

Hint 1

Keep a window of size k and maintain the number of vowels in it.

Hint 2

Keep moving the window and update the number of vowels while moving. Answer is max number of vowels of any window.

7:58

Still stuck?Read 3 approaches, or watch a walkthrough.

Open solution