[Leetcode]@python 90. Subsets II.py

题目链接

https://leetcode.com/problems/subsets-ii/

题目原文

Given a collection of integers that might contain duplicates, nums, return all possible subsets.

Note:
Elements in a subset must be in non-descending order.
The solution set must not contain duplicate subsets.
For example,
If nums = [1,2,2], a solution is:

[
[2],
[1],
[1,2,2],
[2,2],
[1,2],
[]
]

题目大意

给出一个有重复元素的所有集合的子集的list

解题思路

使用dfs进行求解

代码

class Solution(object):
    def subsetsWithDup(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        def dfs(depth, start, valuelist):
            if valuelist not in ans:
                ans.append(valuelist)
            if depth == len(nums):
                return
            for i in range(start, len(nums)):
                dfs(depth + 1, i + 1, valuelist + [nums[i]])

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