collatz.py

#!/usr/bin/python3
from time import time
from argparse import ArgumentParser

__version__ = '1.0.0'

parser = ArgumentParser(description='a simple collatz sequence solver')

parser.add_argument('n', help='number', action='store', type=int)
parser.add_argument('-t', '--time', help='show time taken', action='store_true')
parser.add_argument('-V', '--verbose', help='verbose mode', action='store_true')
parser.add_argument('-v', '--version', help='display version', action='version', version=f'%(prog)s {__version__}')

args = parser.parse_args()


def is_even(num: int):
    if str(num)[-1] in ['0', '2', '4', '6', '8']:
        return True
    return False


num = args.n

if args.time:
    t1 = time()
    counter = 0

while num != 1:
    if args.verbose:
        print(num, end=' ')
    if is_even(num):
        num //= 2
    else:
        num = (num * 3) + 1
    if args.time:
        counter += 1

print(1) if args.verbose else print('', end='')

if args.time:
    t2 = time()

print(f'completed' + (f' in {t2-t1} after {counter} iterations' if args.time else ''))