LCM

#!/usr/bin/python3

import math

print("""Select one option:
        1. LCM of integers from 1 to user-defined N.
        2. LCM of integers in a user-defined range.
        3. LCM of a set of user-defined integers.
        """)
choice = str(input('Input: '))


def calc_lcm(arr):
    lcm = arr[0]

    for i in arr[1:]:
        lcm = int(lcm * i / math.gcd(lcm, i))

    return lcm


if choice == '1':
    in_num = int(input('Upper bound: '))

    arr = []

    for i in range(in_num):
        arr.append(i+1)

    lcm = calc_lcm(arr)
    print(f'LCM integers from 1 to {in_num} = {lcm}')
elif choice == '2':
    lower_bound = int(input('Lower bound: '))
    upper_bound = int(input('Upper bound: '))

    arr = list(range(lower_bound, (upper_bound + 1)))

    lcm = calc_lcm(arr)

    print(f'LCM of integers from {lower_bound} to {upper_bound} = {lcm}')
elif choice == '3':
    arr = []

    while True:
        try:
            arr.append(int(input('Enter an integer or type "c" to quit and calculate LCM: ')))
        except ValueError:
            break

    lcm = calc_lcm(arr)

    out_num = ','.join(str(x) for x in arr)
    print(f'LCM of ({out_num}) = {lcm}')
else:
    print('Select between options 1, 2 and 3.')