/**
 * @param {number[]} nums
 * @return {number[][]}
 */
export const permute = function (nums) {
  const res = []
  const backtrack = (path = []) => {
    if (path.length === nums.length) res.push(path)
    for (const n of nums) {
      !path.includes(n) && backtrack(path.concat(n))
    }
  }
  backtrack()
  return res
}