1456. Maximum Number of Vowels in a Substring of Given Length | LeetCode Solution

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
class Solution
{
public:
    int maxVowels(string s, int k)
    {
        int ans = 0, vowel = 0;
        int st = 0, end = 0;
        int n = s.length();
        while (end < k && end < n)
        {
            if (s[end] == 'a' || s[end] == 'e' || s[end] == 'i' || s[end] == 'o' || s[end] == 'u')
            {
                ans++;
            }
            end++;
        }
        vowel = ans;
        while (end < n)
        {
            if (s[end] == 'a' || s[end] == 'e' || s[end] == 'i' || s[end] == 'o' || s[end] == 'u')
            {
                vowel++;
            }
            if (s[st] == 'a' || s[st] == 'e' || s[st] == 'i' || s[st] == 'o' || s[st] == 'u')
            {
                vowel--;
            }
            st++;
            end++;
            ans = max(ans, vowel);
        }
        return ans;
    }
};