ひとつの集合のすべてのサブセットのPython実現を求めます
1464 ワード
方法一:回帰実現
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
他の方法も続々と整理されますが、もちろん、コメントエリアへのコメントも歓迎です...