59 lines
1.5 KiB
Python
59 lines
1.5 KiB
Python
import numpy as np
|
|
|
|
def sieve_np(limit):
|
|
if limit < 2:
|
|
return []
|
|
|
|
# Create a boolean array "is_prime" and initialize all entries as True
|
|
is_prime = np.ones(limit + 1, dtype=bool)
|
|
is_prime[0:2] = False # 0 and 1 are not prime numbers
|
|
|
|
for p in range(2, int(limit**0.5) + 1):
|
|
if is_prime[p]:
|
|
# Use array slicing to mark all multiples of p as not prime
|
|
is_prime[p**2 : limit + 1 : p] = False
|
|
|
|
# Create a list of prime numbers using NumPy's where function
|
|
primes = np.where(is_prime)[0]
|
|
return primes.tolist()
|
|
|
|
def sieve(max_n):
|
|
s = [True] * (max_n + 1)
|
|
p = 2
|
|
while p**2 <= max_n:
|
|
if s[p]:
|
|
for i in range(p**2, max_n + 1, p):
|
|
s[i] = False
|
|
p += 1
|
|
|
|
primes = [p for p in range(2, max_n + 1) if s[p]]
|
|
return primes
|
|
|
|
|
|
def sieve_of_eratosthenes(limit):
|
|
if limit < 2:
|
|
return []
|
|
|
|
# Create a boolean array "prime[0..limit]" and initialize all entries as True
|
|
prime = [True] * (limit + 1)
|
|
prime[0] = prime[1] = False # 0 and 1 are not prime numbers
|
|
|
|
p = 2
|
|
while p**2 <= limit:
|
|
if prime[p]:
|
|
# Update all multiples of p starting from p^2
|
|
prime[p**2 : limit + 1 : p] = [False] * len(prime[p**2 : limit + 1 : p])
|
|
p += 1
|
|
|
|
# Create a list of prime numbers
|
|
primes = [p for p in range(2, limit + 1) if prime[p]]
|
|
return primes
|
|
|
|
|
|
class Primes:
|
|
primes = sieve(25_000_000)
|
|
|
|
@staticmethod
|
|
def stream():
|
|
yield from Primes.primes
|