from itertools import permutations

def render(l):
   """Render a 3x3 grid of a list `l`."""
   try:
       assert len(l) == 9
   except AssertionError:
       print(f"Expected list of length 9. Got length {len(l)}")

   first_row = f"{l[0]} - {l[1] = {l[2]}"
   second_row = f"{l[3]} ÷ {l[4]} = {l[5]}"
   third_row = f"{l[6]} + {l[7]} = {l[8]}"
   leading_1 = " " * 8 + "x"
   leading_2 = " " * 8 + "="
   padding = '-' * len(first_row)

   rows = [padding, first_row, leading_1, second_row, leading_2, third_row, padding]
   for row in rows:
       print(row)

def generate_lists():
   """Generate all permutations of range(1, 10)."""
   all_perms = list(permutations(range(1, 10)))

   return all_perms

def check_solution(p):
   """Given a permutation of range(1, 10), return True if p solves the puzzle."""
   try:
       assert p[0] - p[1] == p[2]
   except AssertionError:
       return False

   try:
       assert p[3] / p[4] == p[5]
   except AssertionError:
       return False

   try:
       assert p[6] + p[7] == p[8]
   except AssertionError:
       return False

   try:
       assert p[2] * p[5] == p[8]
   except AssertionError:
       return False

   return True

def main():
   all_permutations = generate_lists()
   all_solutions = []
   for index, p in enumerate(all_permutations):
       solved = check_solution(p)
       # print(f'Trying permutation #{index + 1}...')
       if solved:
           print('Solution found! ')
           render(p)
           # print(f'Took {index + 1} guesses to solve.')
           all_solutions.append(p)

   print(f'The total number of solutions is {len(all_solutions)}')

if __name__ == '__main__':
   main()