题解 | #集合的所有子集(一)#

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param S int整型一维数组 
# @return int整型二维数组
#
class Solution:
    def subsets(self , S: List[int]) -> List[List[int]]:
        # write code here
        if S == []:
            return []
        else:
            num = len(S)
            res = []
            for i in range(2**num):
                r = bin(i)[2:].rjust(num,'0')
                r_list = [x for x in r]
                temp = []
                for j in range(num):
                    if r_list[j] == '1':
                        temp.append(j)
                res.append([S[x] for x in temp])
                res.sort()
                res = sorted(res, key=lambda x:len(x))
            return res