137: Subsets 2

Given an array of integers that might contain duplicates, return all possible unique subsets

 

Example 1

Input:   [1, 1]

Output:  [[], [1], [1, 1]]

Example 2

Input:   [1, 2, 2]

Output:  [[], [1], [2], [1, 2, 2], [2, 2], [1, 2]]