【LeetCode】78. 子集 python实现

解题思路

• 回溯算法，解集不能包含重复的子集
• 累加所有子集的不重复的全排列。

python 代码

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

    def backtrace(self,nums,p,start,trace,ret):
        if len(trace) == p:
            ret.append(trace[:])
            return
        
        for i in range(start,len(nums)):
            trace.append(nums[i])
            self.backtrace(nums,p,i+1,trace,ret)
            trace.pop()

s = Solution()
result = s.subsets([1,2,3])
print(result)