17. 子集

class Solution:
    """
    @param nums: A set of numbers.
    @return: A list of lists. All valid subsets.
    """
    ‘‘‘
    大致思路:
    1.循环，取出所有符合的子集，最后加[]进来，返回
    ‘‘‘
    def subsetsWithDup(self, nums):
        res = []
        for i in range(len(nums)):
            if i == 0:
                res.append([nums[i]])
            else:
                for j in range(len(res)):
                    a = sorted(res[j] + [nums[i]])
                    if a not in res:
                        res.append(a)
                if [nums[i]] not in res:
                    res.append([nums[i]])
        res = res + [[]]
        return res