Question

kk是存在的列表数。 l1，l2，l3是列表。在下面的代码中，我使用了3个for循环将元素添加到3个列表中。变量k的值可能会有所不同，因此列表。我想知道如何使用递归来实现这一目标。

kk = 3  
l1 = [8,5,4]
l2 = [3,11,9]
l3 = [5,9,15,8]
maxi = []

for i in l1:
  for j in l2:
    for k in l3:
        maxi.append(i+j+k)

Answer 1

听起来像您在寻找

[sum(t) for t in itertools.product(l1, l2, l3)]

这将导致

[16, 20, 26, 19, 24, 28, 34, 27, 22, 26, 32, 25, 13, 17, 23, 16, 21, 25, 31, 24, 19, 23, 29,
 22, 12, 16, 22, 15, 20, 24, 30, 23, 18, 22, 28, 21]

此处itertools.product生成输入可迭代项的Cartesian product。如果列表中有未知数量的可迭代对象，则可以

iterables = [l1, l2, l3, ...]
[sum(t) for t in itertools.product(*iterables)]

将其解压缩为参数

递归解决方案看起来像这样。警告：与itertools解决方案相比，它在各个方面都会变得更糟。

def summations(*iterables, sums=()):
    if not iterables:
        return list(sums)
    head, *tail = iterables
    if not sums:
        return summations(*tail, sums=head)
    sums = (x+y for y in sums for x in head)
    return summations(*tail, sums=sums)

summations(l1, l2, 3)
# [16, 20, 26, 19, 24, 28, 34, 27, 22, 26, 32, 25, 13, 17, 23, 16, 21, 25, 31, 24, 19, 23, 29,
#  22, 12, 16, 22, 15, 20, 24, 30, 23, 18, 22, 28, 21]

N个for循环，用于n个列表，以将1个列表中的每个元素添加到其余列表

1 个答案: