""" Project Euler Problem 10: https://projecteuler.net/problem=10 Summation of primes The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. References: - https://en.wikipedia.org/wiki/Prime_number - https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes """ def solution(n: int = 2000000) -> int: """ Returns the sum of all the primes below n using Sieve of Eratosthenes: The sieve of Eratosthenes is one of the most efficient ways to find all primes smaller than n when n is smaller than 10 million. Only for positive numbers. >>> solution(1000) 76127 >>> solution(5000) 1548136 >>> solution(10000) 5736396 >>> solution(7) 10 >>> solution(7.1) # doctest: +ELLIPSIS Traceback (most recent call last): ... TypeError: 'float' object cannot be interpreted as an integer >>> solution(-7) # doctest: +ELLIPSIS Traceback (most recent call last): ... IndexError: list assignment index out of range >>> solution("seven") # doctest: +ELLIPSIS Traceback (most recent call last): ... TypeError: can only concatenate str (not "int") to str """ primality_list = [0 for i in range(n + 1)] primality_list[0] = 1 primality_list[1] = 1 for i in range(2, int(n**0.5) + 1): if primality_list[i] == 0: for j in range(i * i, n + 1, i): primality_list[j] = 1 sum_of_primes = 0 for i in range(n): if primality_list[i] == 0: sum_of_primes += i return sum_of_primes if __name__ == "__main__": print(f"{solution() = }")