799. Permutations

You are generating every possible ordering of a set of unique items, such as trying all keyboard shortcut orders, onboarding step orders, or small candidate arrangements.

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

Examples

permute([1,2,3]);
// [
//   [1,2,3], [1,3,2], [2,1,3],
//   [2,3,1], [3,1,2], [3,2,1]
// ]