euler3.py

from random import randint


def is_prime(n):
    return False if n <= 1 else not any(n % x == 0 for x in range(2, int(n ** 0.5) + 1))


def biggest_prime_factor(n):
    '''
    intentionally not using recursion
    '''

    while n % 2 == 0:
        if n == 2:
            return 2
        n /= 2

    if is_prime(n):
        return n

    p = 3
    while True:
        if n % p == 0 and is_prime(p):
            n /= p

            if is_prime(n):
                return n
        else:
            p += 2


for num in (randint(3, 600851475143) for _ in xrange(10)):
    print num,
    print '\t',
    print biggest_prime_factor(num)