In [1]:
import notebook_importer
from shared_functions import fib_gen, factorization, primesfrom2to
from gmpy2 import is_prime
import itertools
import numpy as np
import os
In [2]:
sum(i for i in range(1000) if i%3 == 0 or i%5 == 0)
Out[2]:
Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:
1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.
In [17]:
sum(i for i in fib_gen(4000000) if i%2 == 0)
Out[17]:
In [4]:
def find_large_prime_factor(n):
for i in itertools.count(start=2):
if n % i == 0 and is_prime(n // i):
return n // i
find_large_prime_factor(600851475143)
Out[4]:
In [5]:
def is_palindrome_num(a):
return str(a) == str(a)[::-1]
def find_large_palindrome_prod():
max_r = 0
for a in reversed(range(100, 999)):
for b in reversed(range(100, a+1)):
r = a*b
if is_palindrome_num(r) and r > max_r:
max_r = r
return max_r
find_large_palindrome_prod()
Out[5]:
In [6]:
def find_smallest_evenly_divisible(n):
result = []
for i in range(2,n+1):
new_r = list(result)
for f in factorization(i):
try:
del new_r[new_r.index(f)]
except ValueError:
result.append(f)
return np.prod(result)
find_smallest_evenly_divisible(20)
Out[6]:
The sum of the squares of the first ten natural numbers is, $1^2 + 2^2 + ... + 10^2 = 385$
The square of the sum of the first ten natural numbers is, $(1 + 2 + ... + 10)^2 = 552 = 3025$
Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 − 385 = 2640.
Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum
In [7]:
in_arr = np.arange(1,101)
sum_of_squares = np.power(np.sum(in_arr),2)
square_of_sum = np.sum(np.apply_along_axis(np.power, 0, in_arr, 2))
sum_of_squares - square_of_sum
Out[7]:
In [8]:
for i,p in enumerate(primesfrom2to(1000000), start=1):
if i == 10001:
break
p
Out[8]:
The four adjacent digits in the 1000-digit number that have the greatest product are 9 × 9 × 8 × 9 = 5832.
73167176531330624919225119674426574742355349194934 96983520312774506326239578318016984801869478851843 85861560789112949495459501737958331952853208805511 12540698747158523863050715693290963295227443043557 66896648950445244523161731856403098711121722383113 62229893423380308135336276614282806444486645238749 30358907296290491560440772390713810515859307960866 70172427121883998797908792274921901699720888093776 65727333001053367881220235421809751254540594752243 52584907711670556013604839586446706324415722155397 53697817977846174064955149290862569321978468622482 83972241375657056057490261407972968652414535100474 82166370484403199890008895243450658541227588666881 16427171479924442928230863465674813919123162824586 17866458359124566529476545682848912883142607690042 24219022671055626321111109370544217506941658960408 07198403850962455444362981230987879927244284909188 84580156166097919133875499200524063689912560717606 05886116467109405077541002256983155200055935729725 71636269561882670428252483600823257530420752963450
Find the thirteen adjacent digits in the 1000-digit number that have the greatest product. What is the value of this product?
In [9]:
num_in = """73167176531330624919225119674426574742355349194934
96983520312774506326239578318016984801869478851843
85861560789112949495459501737958331952853208805511
12540698747158523863050715693290963295227443043557
66896648950445244523161731856403098711121722383113
62229893423380308135336276614282806444486645238749
30358907296290491560440772390713810515859307960866
70172427121883998797908792274921901699720888093776
65727333001053367881220235421809751254540594752243
52584907711670556013604839586446706324415722155397
53697817977846174064955149290862569321978468622482
83972241375657056057490261407972968652414535100474
82166370484403199890008895243450658541227588666881
16427171479924442928230863465674813919123162824586
17866458359124566529476545682848912883142607690042
24219022671055626321111109370544217506941658960408
07198403850962455444362981230987879927244284909188
84580156166097919133875499200524063689912560717606
05886116467109405077541002256983155200055935729725
7163626956188267042825248360082325753042075296345"""
length = 13
num_in = num_in.replace(os.linesep,"")
max_prod = 0
max_seg = ""
for i in range(len(num_in)-length):
prod = np.prod(list(map(int,num_in[i:i+13])))
if prod > max_prod:
max_prod = prod
max_seg = num_in[i:i+13]
max_prod
Out[9]:
In [10]:
perfect_squares = np.apply_along_axis(np.power,0,np.arange(1,1000),2)
for a in perfect_squares:
b_indx = np.searchsorted(perfect_squares, a)
for b in perfect_squares[b_indx:]:
c = a + b
if c in perfect_squares and np.sqrt(a)+np.sqrt(b)+np.sqrt(c) == 1000:
result = int(np.sqrt(a)*np.sqrt(b)*np.sqrt(c))
break
result
Out[10]:
In [11]:
np.sum(primesfrom2to(2000000))
Out[11]: