ulam.py

from time import perf_counter


t1_start = perf_counter()

biggest_sequence_len = 0
biggest_sequence_value = 0
sequences_len_sum = 0


def ulam_algorithm(initial_value):
  global biggest_sequence_len
  global biggest_sequence_value
  global sequences_len_sum
  x = initial_value
  seq = [x]

  while len(seq) < 3 or (seq[-3] != 4 and 
        seq[-2] != 2 and seq[-1] != 1):
    if(x % 2 == 0):
      x = x/2
    else:
      x = 3 * x + 1
    seq.append(x)

  if len(seq) > biggest_sequence_len:
    biggest_sequence_len = len(seq)
    biggest_sequence_value = initial_value
  
  sequences_len_sum += len(seq)
  return seq


with open('answer.txt', 'w') as file:
  for i in range(1, 65535 + 1):
    file.writelines(str(i) + ': [' + ', '.join(str(int(number)) for number in ulam_algorithm(i)) + ']\n\n')


t1_stop = perf_counter()


print(f'The biggest sequence length was {biggest_sequence_len} for the value {biggest_sequence_value}')
print(f'The average sequence length was {sequences_len_sum/65535}')
print(f'Time in seconds to run: {t1_stop-t1_start}')