Skip to main content

Subsets II

Problem Statement​

Given an integer array nums of unique elements, return all possible subsets (the power set).

The solution set must not contain duplicate subsets. Return the solution in any order.

Leetcode link

Examples​

Example 1:

Input: nums = [1,2,2]
Output: [[],[1],[1,2],[1,2,2],[2],[2,2]]


Example 2:

Input: nums = [0]
Output: [[],[0]]

Constraints​

  • 1 <= nums.length <= 10
  • -10 <= nums[i] <= 10

Code​

Python3 Code
class Solution:
    def subsetsWithDup(self, nums: List[int]) -> List[List[int]]:
        def backtrack(i, curSubset):
            if i == len(nums):
                ans.append(curSubset[::])
                return

            curSubset.append(nums[i])
            backtrack(i + 1, curSubset)  # Pick
            curSubset.pop()

            if not curSubset or curSubset[-1] != nums[i]:
                backtrack(i + 1, curSubset)  # Don't pick

        nums.sort()
        ans = []
        backtrack(0, [])
        return ans