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)))