LeetCode: Letter Case Permutation Solution

1const recursion = function (chars, set, i = 0) {
2  set.add(chars.join(""))
3
4  if (i === chars.length) {
5    return
6  }
7
8  for (let j = i; j < chars.length; j++) {
9    let temp = chars[j]
10    chars[j] =
11      temp === temp.toLowerCase() ? temp.toUpperCase() : temp.toLowerCase()
12    recursion(chars, set, j + 1)
13    chars[j] = temp
14  }
15}
16
17/**
18 * @param {string} S
19 * @return {string[]}
20 */
21var letterCasePermutation = function (S) {
22  const chars = S.split("")
23  let set = new Set()
24  recursion(chars, set)
25  return Array.from(set)
26}