python解决排列组合

笛卡尔积：itertools.product(*iterables[, repeat])

import itertools

for i in itertools.product('BCDEF', repeat = 2): print(''.join(i),end=\print('\\n')

# 输出 BB BC BD BE BF CB CC CD CE CF DB DC DD DE DF EB EC ED EE EF FB FC FD FE FF　　两个元组进⾏笛卡尔积：import itertoolsa = (1, 2)

b = ('A', 'B', 'C')

c = itertools.product(a,b)for i in c:

print(i,end=\

# 输出(1, 'A') (1, 'B') (1, 'C') (2, 'A') (2, 'B') (2, 'C')

排列：itertools.permutations(iterable[, r])

import itertools

for i in itertools.permutations('BCD', 2): print(''.join(i),end=\

# 输出 BC BD CB CD DB DCprint('\\n')

组合：itertools.combinations(iterable, r)

import itertools

for i in itertools.combinations('BCDEF', 2): print(''.join(i),end=\" \")

# 输出 BC BD BE BF CD CE CF DE DF EFprint('\\n')

组合（包含⾃⾝重复）：itertools.combinations_with_replacement(iterable, r)

import itertools

for i in itertools.combinations_with_replacement('ABC', 3): print (''.join(i),end=' ')

# 输出 AAA AAB AAC ABB ABC ACC BBB BBC BCC CCCprint('\\n')

举例

'BCDEF五个字母组合问题'import itertools

print(\"1个组合：\")

for i, val in enumerate(list(itertools.combinations('BCDEF', 1))): print(\"序号：%s 值：%s\" % (i + 1, ''.join(val)))print(\"2个组合：\")

for i, val in enumerate(list(itertools.combinations('BCDEF', 2))): print(\"序号：%s 值：%s\" % (i + 1, ''.join(val)))print(\"3个组合：\")

for i, val in enumerate(list(itertools.combinations('BCDEF', 3))): print(\"序号：%s 值：%s\" % (i + 1, ''.join(val)))print(\"4个组合：\")

for i, val in enumerate(list(itertools.combinations('BCDEF', 4))): print(\"序号：%s 值：%s\" % (i + 1, ''.join(val)))print(\"5个组合：\")

for i, val in enumerate(list(itertools.combinations('BCDEF', 5))): print(\"序号：%s 值：%s\" % (i + 1, ''.join(val)))