Description
Given an integer array nums that may contain duplicates, return all possible subsets (the power set). The solution set must not contain duplicate subsets.
Examples
nums = [1,2,2][[],[1],[1,2],[1,2,2],[2],[2,2]]With nums = [1,2,2], generate subsets by including 0, 1, or 2 copies of the duplicate '2', combined with whether to include '1'. The subsets are: [] (empty), [1], [2], [1,2], [2,2], and [1,2,2]. Note that [2] appears once, not twice, to avoid duplicate subsets.
nums = [4,4,4][[],[4],[4,4],[4,4,4]]When all elements are identical, it is possible to only form subsets by choosing 0, 1, 2, or all 3 elements. Since all elements are the same value (4), this gives subsets of increasing lengths but no other variations.
nums = [1,2,3,3][[],[1],[1,2],[1,2,3],[1,2,3,3],[1,3],[1,3,3],[2],[2,3],[2,3,3],[3],[3,3]]Sorting gives [1,2,3,3]. For the unique elements 1 and 2, It is possible to include or exclude each. For the duplicate 3's, It is possible to include 0, 1, or 2 copies. This yields subsets like [1,2,3,3] (all elements), [1,3] (one 3), [3,3] (both 3's, no 1 or 2), and [] (empty). The 12 unique subsets avoid duplicates like having two separate [3] entries.
Constraints
- •
1 ≤ nums.length ≤ 10 - •
-10 ≤ nums[i] ≤ 10