def aliquot_sum(input_num: int) -> int: """ Finds the aliquot sum of an input integer, where the aliquot sum of a number n is defined as the sum of all natural numbers less than n that divide n evenly. For example, the aliquot sum of 15 is 1 + 3 + 5 = 9. This is a simple O(n) implementation. @param input_num: a positive integer whose aliquot sum is to be found @return: the aliquot sum of input_num, if input_num is positive. Otherwise, raise a ValueError Wikipedia Explanation: https://en.wikipedia.org/wiki/Aliquot_sum >>> aliquot_sum(15) 9 >>> aliquot_sum(6) 6 >>> aliquot_sum(-1) Traceback (most recent call last): ... ValueError: Input must be positive >>> aliquot_sum(0) Traceback (most recent call last): ... ValueError: Input must be positive >>> aliquot_sum(1.6) Traceback (most recent call last): ... ValueError: Input must be an integer >>> aliquot_sum(12) 16 >>> aliquot_sum(1) 0 >>> aliquot_sum(19) 1 """ if not isinstance(input_num, int): raise ValueError("Input must be an integer") if input_num <= 0: raise ValueError("Input must be positive") return sum(divisor for divisor in range(1, input_num) if input_num % divisor == 0) if __name__ == "__main__": import doctest doctest.testmod()