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