Permutations
Part of Practice: The Big Three
Given an array of distinct integers, return every possible ordering (permutation) of its elements, in any order. For n elements there are n × (n−1) × … × 1 = n! permutations, and all of them must appear exactly once.
The array holds at most 6 elements, so the factorial-sized output is intentional and manageable.
Examples
- Input:
- nums = [1, 2, 3]
- Output:
- [[1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], [3, 2, 1]]
All 3! = 6 orderings of the three elements.
- Input:
- nums = [0, 1]
- Output:
- [[0, 1], [1, 0]]
Two elements have exactly two orderings.
- Input:
- nums = [1]
- Output:
- [[1]]
A single element has one trivial permutation.
Hints
One at a time — struggle first, peek second.
Your thinking space — verify on LeetCode, then mark it.