Problem - Subsets

Given an array of distinct integers, return all possible subsets. The solution set must not contain duplicate subsets.

For example, given $[1, 2, 3]$, return $[[], [1], [2], [3], [1,2], [1,3], [2,3], [1,2,3]]$.

You can solve this with backtracking, but there's a direct bit manipulation approach. Think about representing each subset as a bitmask.