arr = ['a','b','c']

def initialize_counter(n):
  out = []
  for i in range(n):
    out.append(0)
  return out

def increment_counter(arr):
  n = len(arr)
  for i in range(n-1, -1, -1):
    arr[i] += 1
    if arr[i] % n == 0:
      arr[i] = 0
    else:
      break

def permutations(arr):
  out = []
  n = len(arr)**len(arr)

  counter = initialize_counter(len(arr))
  for i in range(n):
    new_permutation = []
    for elem in counter:
      new_permutation.append(arr[elem])
    out.append(new_permutation)
    increment_counter(counter)
  return out

print(permutations(arr))