Reputation: 63
a = []
def make_squares(arr, length, nums):
if not nums:
print(arr)
a.append(arr)
return
r = 0
while r < len(arr) and len(arr[r]) == length:
r += 1
for i in nums:
nums.remove(i)
arr[r].append(i)
make_squares(arr, length, nums)
nums.append(i)
arr[r] = arr[r][:-1]
make_squares([[] for i in range(3)], 3, [i+1 for i in range(3**2)])
print(a)
I'm trying to use the above code to create nxn
matrices each with a permutation of the numbers i+1...n^2
. I have printed every matrix that gets appended to a and they appear correct, but when I print a in the end, I get [[[], [], []], [[], [], []], ...]
. It doesn't make any sense to me.
The expected result would be
[[[1, 2, 3], [4, 5, 6], [7, 8, 9]], [[1, 2, 3], [4, 5, 6], [7, 9, 8]], ...]
Upvotes: 1
Views: 38
Reputation: 169416
The order may not be the same as in your expected result, but this does the trick with the standard library itertools
module:
import itertools
def make_squares(w):
size = w * w
for perm in itertools.permutations(range(1, size + 1)):
# "grouper" from the itertools recipe list
yield list(itertools.zip_longest(*[iter(perm)] * w))
for square in make_squares(3):
print(square)
prints
[(1, 2, 3), (4, 5, 6), (7, 8, 9)]
[(1, 2, 3), (4, 5, 6), (7, 9, 8)]
[(1, 2, 3), (4, 5, 6), (8, 7, 9)]
[(1, 2, 3), (4, 5, 6), (8, 9, 7)]
[(1, 2, 3), (4, 5, 6), (9, 7, 8)]
[(1, 2, 3), (4, 5, 6), (9, 8, 7)]
[(1, 2, 3), (4, 5, 7), (6, 8, 9)]
[(1, 2, 3), (4, 5, 7), (6, 9, 8)]
[(1, 2, 3), (4, 5, 7), (8, 6, 9)]
[(1, 2, 3), (4, 5, 7), (8, 9, 6)]
[(1, 2, 3), (4, 5, 7), (9, 6, 8)]
[(1, 2, 3), (4, 5, 7), (9, 8, 6)]
[(1, 2, 3), (4, 5, 8), (6, 7, 9)]
[(1, 2, 3), (4, 5, 8), (6, 9, 7)]
[(1, 2, 3), (4, 5, 8), (7, 6, 9)]
...
Upvotes: 1