leetcode90. Subsets II

原题链接https://leetcode.com/problems/subsets-ii/

Given a collection of integers that might contain duplicates, nums, return all possible subsets (the power set).

Note: The solution set must not contain duplicate subsets.

Example:

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

class Solution:
    def subsetsWithDup(self, nums: List[int]) -> List[List[int]]:
        
        
        def backtrack(path,nums):
            if not nums:
                return
            for i, num in enumerate(nums):
                if i == 0 or nums[i] != nums[i-1]:
                    path.append(num)
                    res.append(path[:])
                    backtrack(path,nums[i+1:])
                    path.pop()
        nums.sort()
        path = []
        res = []
        backtrack(path,nums)
        return res + [[]]