diff --git a/project_euler/problem_10/sol3.py b/project_euler/problem_10/sol3.py new file mode 100644 index 000000000000..e5bc0731d8ab --- /dev/null +++ b/project_euler/problem_10/sol3.py @@ -0,0 +1,58 @@ +""" +https://projecteuler.net/problem=10 + +Problem Statement: +The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. + +Find the sum of all the primes below two million 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. +""" + + +def prime_sum(n: int) -> int: + """ Returns the sum of all the primes below n. + + >>> prime_sum(2_000_000) + 142913828922 + >>> prime_sum(1_000) + 76127 + >>> prime_sum(5_000) + 1548136 + >>> prime_sum(10_000) + 5736396 + >>> prime_sum(7) + 10 + >>> prime_sum(7.1) # doctest: +ELLIPSIS + Traceback (most recent call last): + ... + TypeError: 'float' object cannot be interpreted as an integer + >>> prime_sum(-7) # doctest: +ELLIPSIS + Traceback (most recent call last): + ... + IndexError: list assignment index out of range + >>> prime_sum("seven") # doctest: +ELLIPSIS + Traceback (most recent call last): + ... + TypeError: can only concatenate str (not "int") to str + """ + list_ = [0 for i in range(n + 1)] + list_[0] = 1 + list_[1] = 1 + + for i in range(2, int(n ** 0.5) + 1): + if list_[i] == 0: + for j in range(i * i, n + 1, i): + list_[j] = 1 + s = 0 + for i in range(n): + if list_[i] == 0: + s += i + return s + + +if __name__ == "__main__": + # import doctest + # doctest.testmod() + print(prime_sum(int(input().strip())))