求一个集合所有子集的Python实现

方法一：回归实现

def PowerSetsRecursive(items):    """Use recursive call to return all subsets of items, include empty set"""        if len(items) == 0:        #if the lsit is empty, return the empty list        return [[]]        subsets = []    first_elt = items[0] #first element    rest_list = items[1:]        #Strategy:Get all subsets of rest_list; for each of those subsets, a full subset list    #will contain both the original subset as well as a version of the sebset that contains the first_elt        for partial_sebset in PowerSetsRecursive(rest_list):        subsets.append(partial_sebset)        next_subset = partial_sebset[:] +[first_elt]        subsets.append(next_subset)    return subsets
def PowerSetsRecursive2(items):    # the power set of the empty set has one element, the empty set    result = [[]]    for x in items:        result.extend([subset + [x] for subset in result])    return result 



方法二：二进制法
def PowerSetsBinary(items):    #generate all combination of N items    N = len(items)    #enumerate the 2**N possible combinations    for i in range(2**N):        combo = []        for j in range(N):            #test jth bit of integer i            if(i >> j ) % 2 == 1:                combo.append(items[j])        yield combo
会陆续整理出其他的方法，当然，也欢迎在评论区留言。。。。。。