Permutations

Permutations

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.

Examples

Example 1:

Input: nums = [1, 2, 3]
Output: [[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1]]

Example 2:

Input: nums = [0, 1]
Output: [[0,1], [1,0]]

Example 3:

Input: nums = [1]
Output: [[1]]

Constraints

• 1 <= nums.length <= 6
• -10 <= nums[i] <= 10
• All the integers of nums are unique

Expected Complexity

• Time: O(n! * n). there are n! permutations, and each takes O(n) to copy
• Space: O(n). recursion depth plus the used-tracking structure (excluding the output)