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61 lines
1.6 KiB
Python
61 lines
1.6 KiB
Python
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from math import ceil , sqrt
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from __future__ import annotations
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def primeproduct(n : int, x : list = []):
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'''
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>>> primeproduct(868)
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[2, 2, 7, 31]
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>>> primeproduct(9039423423423743)
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[2, 2, 7, 31, 719, 12572216166097]
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>>> primeproduct(0.02)
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[]
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'''
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if n < 1:
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return []
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if n > 1:
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if len(x)>=1 and x[-1] % n == 0: # check in already factorised
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x.append(x[-1])
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n = n // x[-1]
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else:
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sq = ceil(sqrt(n))
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flag = 0
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if x != []:
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for i in range(x[-1] , sq+1, 2):
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if n % i == 0:
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n = n // i
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x.append(i)
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flag = 1
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break
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else:
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# Handle factor 2 separately
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while n % 2 ==0: # only 2 is even prime
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n = n // 2
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x.append(2)
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# Start loop from 3 and increment by 2
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for i in range(3 , sq+1, 2): # skip even numbers
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if n % i == 0:
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n = n // i
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x.append(i)
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flag = 1
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break
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if not flag:
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x.append(n)
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n = 1
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return primeproduct(n,x)
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return x
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# faster than https://github.com/sourabhkv/Python/blob/master/maths/prime_factors.py approx 2x
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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