How to nest a "for loop" n times?

Question

for a in range(min_num,max_num+1):
    for b in range(min_num,max_num+1):
        for c in range(min_num,max_num+1):
            for d in range(min_num,max_num+1):
                for e in range(min_num,max_num+1):
                    rows=[e,d,c,b,a]

how would I go about writing this such that rows can be any length? I would like to do this without importing any modules

The requirement to do it without itertools is odd, but you can always put the [same logic as `itertools.product`](https://github.com/python/cpython/blob/master/Modules/itertoolsmodule.c#L2080) into your program. — ggorlen, Oct 13 '20 at 16:22

score 0 · Answer 1 · answered Oct 13 '20 at 16:19

from itertools import product

for i in product(range(3),repeat=3):
    print(i)

gives you

(0, 0, 0)
(0, 0, 1)
(0, 0, 2)
(0, 1, 0)
(0, 1, 1)
(0, 1, 2)
(0, 2, 0)
(0, 2, 1)
(0, 2, 2)
(1, 0, 0)
(1, 0, 1)
(1, 0, 2)
(1, 1, 0)
(1, 1, 1)
(1, 1, 2)
(1, 2, 0)
(1, 2, 1)
(1, 2, 2)
(2, 0, 0)
(2, 0, 1)
(2, 0, 2)
(2, 1, 0)
(2, 1, 1)
(2, 1, 2)
(2, 2, 0)
(2, 2, 1)
(2, 2, 2)

score 0 · Accepted Answer · answered Oct 13 '20 at 16:28

A generator solution:

xss = [],
for _ in range(n):
    xss = ([x] + xs for xs in xss for x in range(min_num, max_num+1))

Demo of using the result (with n = 5 and min_num, max_num = 7, 9):

>>> for xs in xss:
        print(xs)

[7, 7, 7, 7, 7]
[8, 7, 7, 7, 7]
[9, 7, 7, 7, 7]
[7, 8, 7, 7, 7]
[8, 8, 7, 7, 7]
[9, 8, 7, 7, 7]
[7, 9, 7, 7, 7]
[8, 9, 7, 7, 7]
[9, 9, 7, 7, 7]
[7, 7, 8, 7, 7]
...
[9, 9, 8, 9, 9]
[7, 7, 9, 9, 9]
[8, 7, 9, 9, 9]
[9, 7, 9, 9, 9]
[7, 8, 9, 9, 9]
[8, 8, 9, 9, 9]
[9, 8, 9, 9, 9]
[7, 9, 9, 9, 9]
[8, 9, 9, 9, 9]
[9, 9, 9, 9, 9]

How to nest a "for loop" n times?

2 Answers2