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

## 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;
}
};