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

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

Description

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:

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Input: s = "abciiidef", k = 3
Output: 3
Explanation: The substring "iii" contains 3 vowel letters.

Example 2:

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Input: s = "aeiou", k = 2
Output: 2
Explanation: Any substring of length 2 contains 2 vowels.

Example 3:

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Input: s = "leetcode", k = 3
Output: 2
Explanation: "lee", "eet" and "ode" contain 2 vowels.

Constraints:

  • 1 <= s.length <= 10^5
  • s consists of lowercase English letters.
  • 1 <= k <= s.length

Hints/Notes

Solution

Language: C++

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class Solution {
public:
    unordered_set<char> vowels = {'a', 'e', 'i', 'o', 'u'};

    int maxVowels(string s, int k) {
        int res = 0, right = 0, tmp = 0;
        while (right < s.size()) {
            char r = s[right];
            if (vowels.contains(r)) {
                tmp++;
            }
            if (right >= k) {
                char l = s[right - k];
                if (vowels.contains(l)) {
                    tmp--;
                }
            }
            res = max(res, tmp);
            right++;
        }
        return res;
    }
};