Function swap

Backtracking/GeneratePermutations.js:12–18

(arr, i, j)

 */

const swap = (arr, i, j) => {
  const newArray = [...arr]

  ;[newArray[i], newArray[j]] = [newArray[j], newArray[i]] // Swapping elements ES6 way

  return newArray
}

const permutations = (arr) => {
  const P = []