46.Permutations (Medium) Microsoft LinkedIn

Given a collection of distinct numbers, return all possible permutations.

For example,
[1,2,3]have the following permutations:

[
  [1,2,3],
  [1,3,2],
  [2,1,3],
  [2,3,1],
  [3,1,2],
  [3,2,1]
]