Enumerate Every Subset of Distinct Integers

Given an array of distinct integers, return its complete power set: every subset, including the empty subset, exactly once. The report identifies the standard Subsets problem and explicitly permits ordinary enumeration without further optimization. ### Constraints and Clarifications All input values are unique. No numerical size bounds were reported. Subset ordering is not semantically important. For a deterministic practice representation, retain input order within each subset and enumerate decisions in input-index order, visiting exclusion before inclusion. This is output normalization for one complete set, not a request to choose one arbitrary valid subset. Empty input has the single subset []. ### Example For [1,2,3], the normalized enumeration is [[],[3],[2],[2,3],[1],[1,3],[1,2],[1,2,3]]. Other orderings describe the same power set, but the practice convention fixes serialization. ### What a Strong Answer Covers Use choose-or-skip recursion or an equivalent enumeration, copy each completed subset, and explain O(n*2^n) output-sensitive time with O(n) working space excluding output. ### Follow-up Questions - Why must the current subset be copied when adding it to the result? - What changes if the input contains duplicate values?