Python/maths/prime_sieve_eratosthenes.py
Du Yuanchao 4d0a8f2355
Optimized recursive_bubble_sort (#2410)
* optimized recursive_bubble_sort

* Fixed doctest error due whitespace

* reduce loop times for optimization

* fixup! Format Python code with psf/black push

Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
2020-09-10 10:31:26 +02:00

48 lines
839 B
Python

# flake8: noqa
"""
Sieve of Eratosthenes
Input : n =10
Output: 2 3 5 7
Input : n = 20
Output: 2 3 5 7 11 13 17 19
you can read in detail about this at
https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes
"""
def prime_sieve_eratosthenes(num):
"""
print the prime numbers up to n
>>> prime_sieve_eratosthenes(10)
2,3,5,7,
>>> prime_sieve_eratosthenes(20)
2,3,5,7,11,13,17,19,
"""
primes = [True for i in range(num + 1)]
p = 2
while p * p <= num:
if primes[p]:
for i in range(p * p, num + 1, p):
primes[i] = False
p += 1
for prime in range(2, num + 1):
if primes[prime]:
print(prime, end=",")
if __name__ == "__main__":
import doctest
doctest.testmod()
num = int(input())
prime_sieve_eratosthenes(num)