maximum-number-of-vowels-in-a-substring-of-given-length.ts

const v = ['a', 'e', 'i', 'o', 'u']
const check = (str: string) => {
  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
}

export const maxVowels = function (s: string, k: number): number {
  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
}