【LeetCode】90. 子集 II python实现

解题思路

• 回溯算法
• 题目要求解集不能包含重复的子集，所以要设置start

python 代码

class Solution:
    def subsetsWithDup(self, nums: List[int]) -> List[List[int]]:
        ret = []
        trace = []
        for i in range(len(nums),-1,-1):
            self.backtrace(nums,i,0,trace,ret)
        return ret

    def backtrace(self,nums,n,start,trace,ret):
        if len(trace)==n:
            if sorted(trace[:]) not in ret:
                ret.append(sorted(trace[:]))
            return

        for i in range(start,len(nums)):
            trace.append(nums[i])
            self.backtrace(nums,n,i+1,trace,ret)
            trace.pop()

s = Solution()
result = s.subsetsWithDup([1,2,2])
print(result)