LeetCode Problem 90. Subsets II

class (object):
    def subsetsWithDup(self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        """
        思路整理:DFS recursion
        1)对nums进行排序以避免nums中重复元素不聚集在一起如[1,2,4,4,3,4]
        2)从nums中依次取出元素加到path中进行DFS
        3)对于重复元素如[1,2,2]中的2，res中每个以2为开头的数组的只取nums的第一个2
        Explanation
        1)sort nums to gather all same number together
        2)take numbers from nums iteratively and use them to conduct DFS
        3)for same numbers like 2 in [1,2,2],each array only take the first 2 as its
        first 2
        """
        def helper(start,end,path,res): 
            res.append(path)
            for i in range(start,end):
                if i!=start and nums[i]==nums[i-1]:continue
                helper(i+1,end,path+[nums[i]],res)
            return
        res=[]
        nums.sort()
        helper(0,len(nums),[],res)
        return res< 大专栏  LeetCode Problem 90. Subsets IIbr/>