project-euler-100

[RADIOACTIVE] solutions to the first 100 challenges of project euler
git clone git://git.figbert.com/project-euler-100.git
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problem003.py (656B)

      1 # problemName = "Largest prime factor"
      2 # problemNum = 3
      3 # solutionBy = "FIGBERT"
      4 # language = "Python"
      5 # dateCompleted = "21/01/2020"
      6 import math
      7 
      8 def prime_factors(num):
      9     primes = []
     10     factor_limit = int(math.sqrt(num)) + 1
     11     while num % 2 == 0: 
     12         primes.append(2)
     13         num = num / 2
     14     for i in range(3, factor_limit, 2):
     15         while num % i == 0: 
     16             primes.append(i)
     17             num = num / i
     18     if num > 2: 
     19         primes.append(num)
     20     return primes
     21 
     22 if __name__ == "__main__":
     23     answer = max(prime_factors(600851475143))
     24     print(
     25         "The largest prime factor of the number 600851475143 is %s" % answer
     26     )