RosettaCodeData/Task/Prime-decomposition/Python/prime-decomposition-3.py

22 lines
506 B
Python

def fac(n):
step = lambda x: 1 + x*4 - (x/2)*2
maxq = long(math.floor(math.sqrt(n)))
d = 1
q = n % 2 == 0 and 2 or 3
while q <= maxq and n % q != 0:
q = step(d)
d += 1
res = []
if q <= maxq:
res.extend(fac(n//q))
res.extend(fac(q))
else: res=[n]
return res
if __name__ == '__main__':
import time
start = time.time()
tocalc = 2**59-1
print "%s = %s" % (tocalc, fac(tocalc))
print "Needed %ss" % (time.time() - start)