Today I have done leetcode's May LeetCoding Challenge with cpp.

May LeetCoding Challenge 5

Description

Maximum Number of Vowels in a Substring of Given Length

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

Solution

int vowel[128] = {
  ['a'] = 1,
  ['e'] = 1,
  ['i'] = 1,
  ['o'] = 1,
  ['u'] = 1
};
class Solution {
public:
  int maxVowels(string s, int k) {
    int pos = 0;
    int answer = 0;
    int count = 0;
    for(; pos < k; ++pos) {
      count += vowel[s[pos]];
    }
    answer = max(answer, count);
    for(;pos < s.length(); ++pos) {
      count += vowel[s[pos]];
      count -= vowel[s[pos - k]];
      answer = max(answer, count);
    }

    return answer;
  }
};

// Accepted
// 106/106 cases passed (11 ms)
// Your runtime beats 99.57 % of cpp submissions
// Your memory usage beats 29.12 % of cpp submissions (10 MB)