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d403da53db
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9e2ea469db
5 changed files with 16 additions and 106 deletions
16
imp/math/numbers.py
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16
imp/math/numbers.py
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from imp.math.primefac import factors
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def divisors(n: int) -> int:
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'''
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Returns the proper divisors of an integer n.
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Also called the "aliquot parts" of n.
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'''
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pf = factors(n)
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for (prime, multiplicity) in pf:
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def aliquots(n: int) -> int:
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return proper_divisors(n)
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def amicable(n: int) -> int:
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sum(proper_divisors())
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'''
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Terminology:
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Although "divisor" and "factor" mean the same thing.
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When Celeste discusses "divisors of n" it is implied to
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mean "proper divisors of n + n itself", and "factors" are
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the "prime proper divisors of n".
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'''
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from imp.math.primefac import primefac
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def factors(n: int) -> int:
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pfactors: list[tuple[int, int]] = []
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# generate primes and progressively store them in pfactors
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pfgen = primefac(n)
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watching = next(pfgen)
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mult = 1
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# ASSUMPTION: prime generation is (non-strict) monotone increasing
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while True:
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p = next(pfgen, None)
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if p == watching:
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mult += 1
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else:
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pfactors.append((watching, mult))
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watching = p # reset
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mult = 1 # reset
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if p is None:
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break
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return pfactors
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def factors2divisors(pfactors: list[tuple[int, int]],
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sorted: bool = True) -> list[int]:
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'''
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Generates all divisors < n of an integer n given its prime factorisation.
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Input: prime factorisation of n (excluding 1 and n, and duplicates)
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in the typical form: list[(prime, multiplicity)]
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'''
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divisors = [1]
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for (prime, multiplicity) in pfactors:
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extension = []
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for i in range(1, multiplicity+1):
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term = prime**i
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extension.extend(list([divisor*term for divisor in divisors]))
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divisors.extend(extension)
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if sorted: divisors.sort()
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return divisors
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def factors2aliquots(pfactors: list[tuple[int, int]]) -> list[int]:
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return factors2divisors(pfactors)[:-1]
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# "aliquots(n)" is an alias for "divisors(n)"
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def aliquots(n: int) -> int:
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'''
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Returns all aliquot parts (proper divisors) of
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an integer n, that is all divisors 0 < d <= n.
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'''
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return factors2aliquots(factors(n))
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def divisors(n: int) -> int:
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'''
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Returns all divisors 0 < d < n of an integer n.
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'''
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return factors2divisors(factors(n))
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def aliquot_sum(n: int) -> int:
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return sum(aliquots(n))
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def littleomega(n: int) -> int:
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'''
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The Little Omega function counts the number of
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distinct prime factors of an integer n.
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Ref: https://en.wikipedia.org/wiki/Prime_omega_function
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'''
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return len(factors(n))
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def bigomega(n: int) -> int:
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'''
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The Big Omega function counts the total number of
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prime factors (including multiplicity) of an integer n.
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Ref: https://en.wikipedia.org/wiki/Prime_omega_function
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'''
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return sum(factor[1] for factor in factors(n))
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def factorial(n: int) -> int:
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if n == 0: return 1
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return n * factorial(n-1)
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def
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from math import gcd
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from math import gcd
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from imp.math.numbers import bigomega
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def coprime(n: int, m: int) -> bool:
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return gcd(n, m) == 1
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def almostprime(n: int, k: int) -> bool:
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'''
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A natural n is "k-almost prime" if it has exactly
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k prime factors (including multiplicity).
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'''
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return (bigomega(n) == k)
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def semiprime(n: int) -> bool:
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'''
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A semiprime number is one that is 2-almost prime.
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Ref: https://en.wikipedia.org/wiki/Semiprime
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'''
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return almostprime(n, 2)
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'''
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'''
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Euler's Totient (Phi) Function
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Euler's Totient (Phi) Function
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