30-seconds-of-code/snippets/python/s/prime-factors.md

title, type, language, tags, cover, dateModified

title	type	language	tags	cover	dateModified
Prime factors of number	snippet	python	math algorithm	river-flow	2023-05-24T05:00:00+02:00

Finds and returns the list of prime factors of a number.

• Use a while loop to iterate over all possible prime factors, starting with 2.
• If the current factor exactly divides num, add factor to the factors list and divide num by factor. Otherwise, increment factor by one.

def prime_factors(num):
  factors = []
  factor = 2
  while (num >= 2):
    if (num % factor == 0):
      factors.append(factor)
      num = num / factor
    else:
      factor += 1
  return factors

prime_factors(12) # [2,2,3]
prime_factors(42) # [2,3,7]