In [1]:

    

!factor 600851475143 | rev | awk '{print $1}' | rev


    

    




6857

In [2]:

    

!factor 600851475143 | awk '{print $NF}'


    

    




6857

In [3]:

    

import math

def get_factors(x):
    '''Returns of prime factors of x in ascending order.'''
    factors = []
    factor = 2
    while factor <= math.sqrt(x):
        while x % factor == 0:
            factors.append(factor)
            x /= factor
        factor += 1
    if x != 1:
        factors.append(x)
    return factors


    

In [4]:

    

n = 600851475143


    

In [5]:

    

get_factors(n)


    

    
Out[5]:





[71, 839, 1471, 6857L]

In [6]:

    

def foo(x):
    return get_factors(x)[-1]


    

In [7]:

    

%timeit foo(n)
foo(n)


    

    




1000 loops, best of 3: 1.34 ms per loop






    
Out[7]:





6857L

In [8]:

    

def get_factors(x):
    '''Returns of prime factors of x in ascending order.'''
    factors = []
    factor = 2
    while factor * factor <= x:
        while x % factor == 0:
            factors.append(factor)
            x /= factor
        factor += 1
    if x != 1:
        factors.append(x)
    return factors


    

In [9]:

    

%timeit foo(n)
foo(n)


    

    




1000 loops, best of 3: 973 us per loop






    
Out[9]:





6857L

In [10]:

    

get_factors(1000)


    

    
Out[10]:





[2, 2, 2, 5, 5, 5]

In [11]:

    

get_factors(600851475143)


    

    
Out[11]:





[71, 839, 1471, 6857L]

In [12]:

    

get_factors(600851475143)[-1]


    

    
Out[12]:





6857L

In [13]:

    

def get_factors(x):
    '''Returns of prime factors of x in ascending order.'''
    factors = []
    factor = 2
    while factor * factor <= x:
        while x % factor == 0:
            factors.append(factor)
            x /= factor
        factor += 1
    if x != 1:
        factors.append(x)
    return factors


    

In [14]:

    

from euler import get_factors2
get_factors = get_factors2


    

In [15]:

    

%timeit foo(n)
foo(n)


    

    




10000 loops, best of 3: 188 us per loop






    
Out[15]:





6857L

In [16]:

    

from euler import get_factors3
get_factors = get_factors3


    

In [17]:

    

%timeit foo(n)
foo(n)


    

    




1000 loops, best of 3: 229 us per loop






    
Out[17]:





6857L

In [18]:

    

from euler import get_factors4
get_factors = get_factors4


    

In [19]:

    

%timeit foo(n)
foo(n)


    

    




1000000 loops, best of 3: 661 ns per loop






    
Out[19]:





6857L

In [20]:

    

from euler import get_factors


    

In [21]:

    

%timeit foo(n)
foo(n)


    

    




1000000 loops, best of 3: 661 ns per loop






    
Out[21]:





6857L

In [22]:

    

from euler import get_factors5
get_factors = get_factors5


    

In [23]:

    

%timeit foo(n)
foo(n)


    

    




1000000 loops, best of 3: 661 ns per loop






    
Out[23]:





6857L

In [24]:

    

from euler import canonical_decomposition2
foo = canonical_decomposition2
%timeit foo(n)
foo(n)


    

    




10000 loops, best of 3: 197 us per loop






    
Out[24]:





{71: 1, 839: 1, 1471: 1, 6857L: 1}

In [25]:

    

from euler import canonical_decomposition3
foo = canonical_decomposition3
%timeit foo(n)
foo(n)


    

    




10000 loops, best of 3: 192 us per loop






    
Out[25]:





{71: 1, 839: 1, 1471: 1, 6857L: 1}

In [26]:

    

from euler import canonical_decomposition4
foo = canonical_decomposition4
%timeit foo(n)
foo(n)


    

    




10000 loops, best of 3: 197 us per loop






    
Out[26]:





Counter({6857L: 1, 839: 1, 1471: 1, 71: 1})

In [27]:

    

from euler import canonical_decomposition5
foo = canonical_decomposition5
%timeit foo(n)
foo(n)


    

    




1000 loops, best of 3: 235 us per loop






    
Out[27]:





Counter({6857L: 1, 839: 1, 1471: 1, 71: 1})

In [28]:

    

from euler import canonical_decomposition
foo = canonical_decomposition
%timeit foo(n)
foo(n)


    

    




1000 loops, best of 3: 230 us per loop






    
Out[28]:





{71: 1, 839: 1, 1471: 1, 6857L: 1}