LeetCode 1456 定长子串中元音的最大数目

方法1：滑动窗口

class Solution {
    public int maxVowels(String s, int k) {
        int n = s.length(), count = 0, ans = 0;
        for (int i = 0; i < n; i++) {
            count += isVowel(s.charAt(i));
            if (i >= k) {
                count -= isVowel(s.charAt(i - k));
            }
            ans = Math.max(count, ans);
        }
        return ans;
    }

    public int isVowel(char ch) {
        return ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u' ? 1 : 0;
    }
}

class Solution:
    def maxVowels(self, s: str, k: int) -> int:
        count = 0; ans = 0
        for i, ch in enumerate(s):
            count += 1 if ch in "aeiou" else 0
            if i >= k:
                count -= 1 if s[i - k] in "aeiou" else 0
            ans = max(ans, count)
        return ans