Generate all permutations of an array

Problem

Given an array nums of distinct integers, return all possible permutations of the array.

A permutation is an ordering of all elements in the array, and each element must appear exactly once in each permutation.

Input

• nums : an array of integers with no duplicates.

Output

• A list of permutations, where each permutation is a list/array of integers.
• You may return the permutations in any order .

Constraints

• 1 <= nums.length <= 10
• -10 <= nums[i] <= 10
• All values in nums are unique.

Example

Input: nums = [1,2,3]

Output (one valid ordering):

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

Notes

• Aim for a solution using DFS/backtracking.
• Consider how to track which elements have been used in the current partial permutation.