Python/project_euler/problem_10/sol1.py
Vladimir Evgrafov e74adc4a6d
Project Euler Problem 10: style improvements (#2924)
Rename the main solution functions to solution.
Rename prime chec functions to is_prime.
Add default args, typehints, expand variable names.
2020-10-06 17:48:07 +05:30

59 lines
1.1 KiB
Python

"""
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.
"""
from math import sqrt
def is_prime(n: int) -> bool:
"""Returns boolean representing primality of given number num.
>>> is_prime(2)
True
>>> is_prime(3)
True
>>> is_prime(27)
False
>>> is_prime(2999)
True
"""
for i in range(2, int(sqrt(n)) + 1):
if n % i == 0:
return False
return True
def solution(n: int = 2000000) -> int:
"""Returns the sum of all the primes below n.
# The code below has been commented due to slow execution affecting Travis.
# >>> solution(2000000)
# 142913828922
>>> solution(1000)
76127
>>> solution(5000)
1548136
>>> solution(10000)
5736396
>>> solution(7)
10
"""
if n > 2:
sum_of_primes = 2
else:
return 0
for i in range(3, n, 2):
if is_prime(i):
sum_of_primes += i
return sum_of_primes
if __name__ == "__main__":
print(solution(int(input().strip())))