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

tags: Medium,String,Sliding Window

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

題目描述

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'.

範例

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

解答

Python

class Solution:
    def maxVowels(self, s: str, k: int) -> int:
        vowels = 'aeiou'
        count = 0
        for i in range(k):
            count += s[i] in vowels
        ans = count
        for i in range(k, len(s)):
            count -= s[i - k] in vowels
            count += s[i] in vowels
            ans = max(ans, count)
        return ans

Yen-Chi ChenFri, May 5, 2023

class Solution:
    def maxVowels(self, s: str, k: int) -> int:
        i, j = 0, 0
        vowels = 'aeiou'
        max_length = 0
        count_vowel = 0

        while i < len(s) and j < len(s):
            if j - i < k:
                if s[j] in vowels:
                    count_vowel += 1
                    max_length = max(max_length, count_vowel)
                j += 1
            else:
                if s[i] in vowels:
                    count_vowel -= 1
                i += 1

        return max_length

Ron ChenFri, May 5, 2023

TypeScript

function maxVowels(s: string, k: number): number {
  let max = 0;
  let currentMax = 0;
  const vowels = ['a', 'e', 'i', 'o', 'u'];
  const queue: string[] = [];

  for (let i = 0; i < s.length; i++) {
    if (queue.length < k) {
      if (vowels.includes(s[i])) currentMax++;
      queue.push(s[i]);
    } else {
      if (vowels.includes(queue.shift()!)) currentMax--;
      if (vowels.includes(s[i])) currentMax++;
      queue.push(s[i]);
    }

    if (currentMax > max) max = currentMax;
  }

  return max;
}

學習了

function maxVowels(s: string, k: number): number {
  let max = 0;
  let currentMax = 0;
  const vowels = ['a', 'e', 'i', 'o', 'u'];

  for (let i = 0; i < s.length; i++) {
    if (i < k && vowels.includes(s[i])) {
      currentMax++;
    } else {
      if (vowels.includes(s[i])) currentMax++;
      if (vowels.includes(s[i - k])) currentMax--;
    }

    max = Math.max(max, currentMax);
  }

  return max;
}

SheepFri, May 5, 2023

C#

public int MaxVowels(string s, int k) {
    string vowels = "aeiou";
    int count = s.Take(k).Count(c => vowels.Contains(c));
    int max = 0;

    for(int i = k; i < s.Length; i++) {
        if (vowels.Contains(s[i])) count++;
        if (vowels.Contains(s[i-k])) count--;
        max = Math.Max(max, count);
    }

    return max;
}

JimFri, May 5, 2023

Javascript

function maxVowels(s, k) {
  const vowels = ['a', 'e', 'i', 'o', 'u'];
  let count = 0;
  for (let i = 0; i < k; i++) {
    if (vowels.includes(s[i])) count++;
  }

  let max = count;

  for (let i = k; i < s.length; i++) {
    if (vowels.includes(s[i])) count++;
    if (vowels.includes(s[i - k])) count--;

    max = Math.max(max, count);
  }

  return max;
}

MarsgoatFri, May 5, 2023

Reference

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