""" Euler Problem 26 https://projecteuler.net/problem=26 Find the value of d < 1000 for which 1/d contains the longest recurring cycle in its decimal fraction part. """ def find_digit(numerator: int, digit: int) -> int: """ Considering any range can be provided, because as per the problem, the digit d < 1000 >>> find_digit(1, 10) 7 >>> find_digit(10, 100) 97 >>> find_digit(10, 1000) 983 """ the_digit = 1 longest_list_length = 0 for divide_by_number in range(numerator, digit + 1): has_been_divided = [] now_divide = numerator for division_cycle in range(1, digit + 1): if now_divide in has_been_divided: if longest_list_length < len(has_been_divided): longest_list_length = len(has_been_divided) the_digit = divide_by_number else: has_been_divided.append(now_divide) now_divide = now_divide * 10 % divide_by_number return the_digit # Tests if __name__ == "__main__": import doctest doctest.testmod()