[leetcode] 90. Subsets II @ python

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原题

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],
[]
]

解法

DFS + 回溯法

代码

class Solution(object):
    def subsetsWithDup(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        def dfs(nums, index, path, res):
            res.append(path)
            for i in range(index, len(nums)):
                if i > index and nums[i] == nums[i-1]:
                    continue
                dfs(nums, i+1, path + [nums[i]], res)
            
        res = []
        nums.sort()
        dfs(nums, 0, [], res)
        return res