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de1f3cc Oct 12, 2016
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@famzah @boromil
42 lines (37 sloc) 861 Bytes
import os
import sys
import time
def get_primes7(n):
"""
standard optimized sieve algorithm to get a list of prime numbers
--- this is the function to compare your functions against! ---
"""
if n < 2:
return []
if n == 2:
return [2]
# do only odd numbers starting at 3
if sys.version_info.major <= 2:
s = range(3, n + 1, 2)
else: # Python 3
s = list(range(3, n + 1, 2))
# n**0.5 simpler than math.sqr(n)
mroot = n ** 0.5
half = len(s)
i = 0
m = 3
while m <= mroot:
if s[i]:
j = (m * m - 3) // 2 # int div
s[j] = 0
while j < half:
s[j] = 0
j += m
i = i + 1
m = 2 * i + 3
return [2] + [x for x in s if x]
start_time = int(time.time())
period_time = int(os.environ['RUN_TIME'])
while (int(time.time()) - start_time) < period_time:
res = get_primes7(10000000)
print("Found {} prime numbers.".format(len(res)))