CODEWITHSUNDEEP
python-3.x
Александр Мельчаков
Александр Мельчаков

Reputation: 11

Code is right, but calculate isn't finished

I'm trying to solve Problem 3 from this site https://projecteuler.net/problem=3 and it is call like this: ''The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number 600851475143 ? '' Why , when I trying run my code with large numbers (more, than 1000000) - it is print on screen nothng ? How can I solve this problem and solve this task?

I have some correct working code, that is work with small input argument ( like 13195. But, when I trying to take the answer with large argument, like 600851475143 and run this code, it is print nothng.

def is_it_prime(x): # function check: is it number a prime or not and return True or False?
    if x != 1: 
        i = int(x/2)
    else:
        i = 1 # x == 1 It is a simple case, where is argument - it is a prime number
    while i != 1:
        if x % i == 0: # This number isn't prime
            return False
        i -= 1
    return True # Done! We find largest prime number

def largest_prime(x): # function check argument on whole divide availible
    i = int(x/2)
    while True:
        if x % i == 0: # argument have whole divide
            if is_it_prime(i) == True:
                break
        i -=1
    return i # It is the largest prime factor


print(largest_prime(600851475143))
--------------------------------------------------------

>>>

Upvotes: 0

Views: 28

Answers (1)

user11891566
user11891566

Reputation:

**How to determine if a number is prime

A computer can be used to test extremely large numbers to see if they are prime. But, because there is no limit to how large a natural number can be, there is always a point where testing in this manner becomes too great a task even for the most powerful supercomputers.**

https://whatis.techtarget.com/definition/prime-number

Upvotes: 1

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