add: 定长子串中元音的最大数目

.vscode/settings.json

@@ -6,6 +6,7 @@
     "Paddr",
     "Prinme",
     "abcdefg",
+    "abciiidef",
     "cdefgab",
     "chuan",
     "defang",

README.md

@@ -113,6 +113,10 @@ LeetCode 与 LintCode 解题记录。此为个人练习仓库，代码中对重
 
   - LeetCode 5416. 检查单词是否为句中其他单词的前缀 <https://leetcode-cn.com/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/>
 
+- [定长子串中元音的最大数目](src/string/maximum-number-of-vowels-in-a-substring-of-given-length.js)
+
+  - LeetCode 5417. 定长子串中元音的最大数目 <https://leetcode-cn.com/problems/maximum-number-of-vowels-in-a-substring-of-given-length/>
+
 ## 数组/队列/集合/映射
 
 - [电话号码的字母组合](src/array/letter-combinations-of-a-phone-number.js)

src/string/maximum-number-of-vowels-in-a-substring-of-given-length.js

@@ -0,0 +1,45 @@
+const v = ['a', 'e', 'i', 'o', 'u']
+const check = (str) => {
+  const map = new Map()
+
+  for (let i = 0; i < str.length; i++) {
+    if (v.includes(str[i])) {
+      map.set(str[i], (map.get(str[i]) || 0) + 1)
+    }
+  }
+
+  let res = 0
+  map.forEach(n => {
+    res += n
+  })
+  return res
+}
+
+/**
+ * @param {string} s
+ * @param {number} k
+ * @return {number}
+ */
+export const maxVowels = function (s, k) {
+  let i = 0
+  let res = 0
+
+  const temp = s.slice(i, i + k)
+  let tmp = check(temp)
+  res = Math.max(res, tmp)
+
+  while (i + k <= s.length) {
+    i++
+    if (v.includes(s[i + k - 1])) {
+      tmp++
+    }
+
+    if (v.includes(s[i - 1])) {
+      tmp--
+    }
+
+    res = Math.max(res, tmp)
+  }
+
+  return res
+}

test/string/maximum-number-of-vowels-in-a-substring-of-given-length.test.js

@@ -0,0 +1,6 @@
+import { maxVowels } from '../../src/string/maximum-number-of-vowels-in-a-substring-of-given-length'
+
+test('定长子串中元音的最大数目', () => {
+  expect(maxVowels('abciiidef', 3)).toBe(3)
+  expect(maxVowels('rhythms', 4)).toBe(0)
+})