add: 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

@@ -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
+}