[Leetcode Series] [] [medium] algorithm subset II

topic:

Topic links:  https://leetcode-cn.com/problems/subsets-ii/

 

Problem-solving ideas:

"All possible" = + prune back

To consider not contain duplicate subset, so when traversing, as if an element has traversed the first character, you need to skip the same elements, use the next non-repeating elements continue backtracking

 

Code:

class Solution:
    def subsetsWithDup(self, nums: List[int]) -> List[List[int]]:
        def create_res(start, nums, res, path):
            if start > len(nums):
                return
            
            for index in range(start, len(nums)):
                if index > start and nums[index] == nums[index - 1]:
                    continue
                    
                path.append(nums[index])
                res.append(path[:])
                create_res(index + 1, nums, res, path)
                path.pop()
                
        nums.sort()
        res = [[]]
        create_res(0, nums, res, [])
        return res