from itertools import permutations,combinations,product
#方法一和方法二,均实现了,输入一个字符串,输出各种排列,不考虑顺序
strs = 'abc'
#方法1
def zuHe(strs):
n = len(strs)
if not n:
return strs
lts = []
for i in range(1,n+1):
for j in permutations(strs,i):
flage = True #定义一个旗帜
for k in permutations(j): #检查全排列中的某一种,是否已经存在于lts中,因为不考虑顺序
# for k in permutations(j,i): #permutations,不加参数i,默认就是全排列
k_strs = ''.join(k)
if k_strs in lts:
flage = False
break
if flage:
j_strs = ''.join(j)
lts.append(j_strs)
return lts
#方法2
def zuHe2(strs):
n = len(strs)
if not n:
return strs
lts = []
for i in range(1,n+1):
for j in combinations(strs,i):
flage = True #定义一个旗帜
# 检查全排列中的某一种,是否已经存在于lts中,因为不考虑顺序 combinations需要指定参数i
for k in combinations(j,i):
k_strs = ''.join(k)
if k_strs in lts:
flage = False
break
if flage:
j_strs = ''.join(j)
lts.append(j_strs)
return lts
#笛卡尔,多用在组合矩阵方面
for m in product([1,2],repeat=3):
print(m)
'''
(1, 1, 1)
(1, 1, 2)
(1, 2, 1)
(1, 2, 2)
(2, 1, 1)
(2, 1, 2)
(2, 2, 1)
(2, 2, 2)
'''
if __name__ == '__main__':
print(zuHe(strs)) #['a', 'b', 'c', 'ab', 'ac', 'bc', 'abc']
print(zuHe2(strs)) #['a', 'b', 'c', 'ab', 'ac', 'bc', 'abc']
