Print N-length Combinations From Char List Using Recursion

I have to solve this exercise using recursion. Implement a function in Python which recieves as parameters list of characters and an integer n. The function has to print all the p

Solution 1:

You are quite close. Instead of len(char_list) == 1, you need to check that the length of your accumulated "pool" list is equal to the parameter n. However, to create a list to accumulate the combinations, create one additional parameter in the signature of the function:

defprint_sequences(char_list, n, _accum):
  iflen(_accum) == n:
     print(_accum)
  else:
     for c in char_list:
        print_sequences(char_list, n, _accum+[c])


print_sequences([1, 2, 3, 4], 4, [])

Output:

[1, 1, 1, 1]
[1, 1, 1, 2]
[1, 1, 1, 3]
[1, 1, 1, 4]
[1, 1, 2, 1]
[1, 1, 2, 2]
[1, 1, 2, 3]
[1, 1, 2, 4]
[1, 1, 3, 1]
[1, 1, 3, 2]
[1, 1, 3, 3]
[1, 1, 3, 4]
[1, 1, 4, 1]
[1, 1, 4, 2]
[1, 1, 4, 3]
[1, 1, 4, 4]
[1, 2, 1, 1]
....

Edit: implementing _accum as a default list:

defprint_sequences(char_list, n, _accum=[]):
  iflen(_accum) == n:
    print(_accum)
  else:
    for c in char_list:
      print_sequences(char_list, n, _accum+[c])

print_sequences([1, 2, 3, 4], 4)