Python实现求一个集合所有子集的示例

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

来源：https://blog.csdn.net/tszw1007/article/details/77871133