Practice/Meta/Leetcode 46. Permutations

Leetcode 46. Permutations

CodingOptional

Problem

You are given an array of distinct integers. Your task is to return all possible arrangements of these numbers. Each arrangement should include all elements from the original array exactly once, but in a different order.

For example, if given [1, 2, 3], you should return all six ways these three numbers can be ordered: [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].

Requirements

1. Return a list containing all possible orderings of the input array
2. Each ordering must contain all elements from the input exactly once
3. All integers in the input array are distinct (no duplicates)
4. The order of permutations in your output does not matter

Constraints

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

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]] Explanation: There are 6 permutations (3! = 6) of the three numbers

Example 2:

Input: nums = [0, 1] Output: [[0,1],[1,0]] Explanation: Two elements can be arranged in only 2 ways

Example 3:

Input: nums = [1] Output: [[1]] Explanation: A single element has only one possible arrangement