给定一组不含重复元素的整数数组 nums,返回该数组所有可能的子集(幂集)。
说明:解集不能包含重复的子集。
示例:
输入: nums = [1,2,3]
输出:
[
[3],
[1],
[2],
[1,2,3],
[1,3],
[2,3],
[1,2],
[]
]
来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/subsets
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class Solution(object): def subsets(self, nums): """ :type nums: List[int] :rtype: List[List[int]] """ if len(nums) == 0: return [] res = [] self.helper(nums, res, [], 0) return res def helper(self, nums, res, tmp, level): if len(tmp) <= len(nums): # 拷贝tmp并添加进res,不进行拷贝,由于tmp的地址不变, # 将会由tmp最后的状态(tmp在最后进行了出栈操作,故最后的状态为空)的值覆盖 res.append(tmp[:]) #print("res", res) #print("tmp", level, tmp) for i in range(level, len(nums)): tmp.append(nums[i]) self.helper(nums, res, tmp, i + 1) #print("pop", i, level, tmp.pop()) tmp.pop()
class Solution: def subsets(self, nums): """ :type nums: List[int] :rtype: List[List[int]] """ if len(nums) == 0: return [] res = [] for i in range(len(nums)+1): self.helper(nums,i,0,[],res) return res def helper(self,nums,length,index,cur,res): if len(cur) == length: res.append(cur[:]) return for i in range(index,len(nums)): cur.append(nums[i]) self.helper(nums,length,i+1,cur,res) cur.pop()