leetcode-90-子集②

题目描述：

 

方法一：回溯

class Solution:
    def subsetsWithDup(self, nums: List[int]) -> List[List[int]]:
        nums.sort()
        if not nums:
            return []
        n = len(nums)
        res = []
        def backtrack(i,temp):
            if temp not in res:
                res.append(temp)
            for j in range(i,n):
                backtrack(j+1,temp+[nums[j]])
        backtrack(0,[])
        return res