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primes.py
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primes.py
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import math
def primes(n):
candidates = set(range(2, n))
for i, num in enumerate(list(candidates)[:len(candidates)/2]):
for candidate in list(candidates)[i+1:]:
if candidate % num == 0:
candidates.remove(candidate)
return list(candidates)
def largest_prime_factor(n, candidates, minimum):
for candidate in candidates:
if candidate <= minimum:
next
if n % candidate == 0:
return n / candidate
return None
def primes_alt(n):
candidates = set(xrange(2, n))
for num in list(candidates)[:len(candidates)/2+1]: #[:len(candidates)/2]:
if num not in candidates:
next
for j in xrange(2,n/num+1):
if j*num in candidates:
#print "num,j"
#print num
#print j
candidates.remove(j*num)
return list(candidates)