Leetcode 78 & 90. Subsets I&II

Subsets I
Given a set of distinct integers, nums, return all possible subsets (the power set).

Note: The solution set must not contain duplicate subsets.

Example:

Input: nums = [1,2,3]
Output:
[
[3],
[1],
[2],
[1,2,3],
[1,3],
[2,3],
[1,2],
[]
]

class Solution:
    def subsets(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        res=[]
        self.dfs(nums,0,[],res)
        return res
    def dfs(self,nums,index,tmp,res):
        res.append(tmp)
        for i in range(index,len(nums)):
            self.dfs(nums,i+1,tmp+[nums[i]],res)

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):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        res=[]
        nums.sort()#special case:[4,4,4,1,4]
        self.generate([],res,0,nums)
        return res
    def generate(self,tmp,res,index,nums):
        res.append(tmp)
        for i in range(index,len(nums)):
            if i>index and nums[i-1]==nums[i]:
                continue
            self.generate(tmp+[nums[i]],res,i+1,nums)