In [7]:
import numpy as np
import math
import timeit
from collections import defaultdict, Counter
from functools import reduce, lru_cache
from multiprocessing import Pool
import itertools
import tqdm
import matplotlib.pyplot as plt
import datetime
import string
from math import sqrt
%matplotlib inline
In [2]:
def is_prime(number):
if number > 1:
if number == 2:
return True
if number % 2 == 0:
return False
for current in range(3, int(math.sqrt(number) + 1), 2):
if number % current == 0:
return False
return True
else:
return False
In [70]:
num = 600851475143
sqr = math.ceil(math.sqrt(num))
if sqr % 2 == 0:
sqr -= 1
for i in range(sqr, 3, -2):
if num % i == 0 and is_prime(i):
print(i)
break
In [31]:
def prime_list(n):
if n > 2:
list_of_primes = [2]
else:
return []
for i in range(3, n, 2):
if is_prime(i):
list_of_primes.append(i)
return list_of_primes
In [16]:
def prime_generator(n):
if n % 2 == 0:
i = n-1
else:
i = n
while i > 1:
if is_prime(i):
yield i
i -= 2
if n > 1:
yield 2
In [13]:
pg = prime_generator(13)
In [6]:
prime_list(10)
Out[6]:
In [69]:
test_number = 600851475143
for prime in prime_generator(math.ceil(math.sqrt(test_number))):
if test_number % prime == 0:
print(prime)
break
else:
print("Something went wrong")
In [11]:
8*9*5*7
Out[11]:
In [26]:
def prime_factorization(n):
factor = 2
factors = defaultdict(int)
while n > 1:
if n % factor == 0:
n /= factor
factors[factor] += 1
else:
break
factor = 3
while n > 1:
if n % factor == 0:
n /= factor
factors[factor] += 1
else:
factor += 2
return factors
In [51]:
most_prime_factors = defaultdict(int) # defaults to 0
for divisor in range(2, 21):
for prime_factor, occurances in prime_factorization(divisor).items():
if occurances > most_prime_factors[prime_factor]:
most_prime_factors[prime_factor] = occurances
In [52]:
total = 1
for prime_factor, occurance in most_prime_factors.items():
total *= prime_factor**occurance
print(total)
In [56]:
reduce(lambda x, y: x*y, [prime_factor**occurances for prime_factor, occurances in most_prime_factors.items()])
Out[56]:
In [43]:
pool = Pool()
In [34]:
def is_prime(number, list_of_primes):
for old_prime in list_of_primes:
if old_prime**2 > number: # if we have gotten past the point of no return
return True
if number % old_prime == 0:
return False
raise RuntimeError("Should not have gotten here")
In [35]:
def is_prime2(number, list_of_primes, number_of_primes):
#print(list_of_primes, number_of_primes)
for old_prime in list_of_primes[:number_of_primes]:
if old_prime**2 > number: # if we have gotten past the point of no return
return True
if number % old_prime == 0:
return False
raise RuntimeError("Should not have gotten here")
In [47]:
def tester(args):
old_prime = args[0]
number = args[1]
if old_prime**2 > number: # if we have gotten past the point of no return
return True
if number % old_prime == 0:
return False
return True
def is_prime3(number, list_of_primes):
new_list = [(prime, number) for prime in list_of_primes]
list_of_bools = pool.map(tester, new_list)
return all(list_of_bools)
#for old_prime in list_of_primes:
#raise RuntimeError("Should not have gotten here")
In [38]:
n = 10001
prime_count = 1
list_of_primes = [2] # make a list of length n
number = 3
while(prime_count < n):
if is_prime(number, list_of_primes): # if number is prime
#list_of_primes[prime_count] = number
prime_count += 1
list_of_primes.append(number)
number += 1
print(list_of_primes[-1])
In [ ]:
n = 10001
prime_count = 1
list_of_primes = [2] # make a list of length n
number = 3
while(prime_count < n):
if is_prime3(number, list_of_primes): # if number is prime
#list_of_primes[prime_count] = number
prime_count += 1
list_of_primes.append(number)
number += 1
print(list_of_primes[-1])
In [4]:
in_string = """
73167176531330624919225119674426574742355349194934
96983520312774506326239578318016984801869478851843
85861560789112949495459501737958331952853208805511
12540698747158523863050715693290963295227443043557
66896648950445244523161731856403098711121722383113
62229893423380308135336276614282806444486645238749
30358907296290491560440772390713810515859307960866
70172427121883998797908792274921901699720888093776
65727333001053367881220235421809751254540594752243
52584907711670556013604839586446706324415722155397
53697817977846174064955149290862569321978468622482
83972241375657056057490261407972968652414535100474
82166370484403199890008895243450658541227588666881
16427171479924442928230863465674813919123162824586
17866458359124566529476545682848912883142607690042
24219022671055626321111109370544217506941658960408
07198403850962455444362981230987879927244284909188
84580156166097919133875499200524063689912560717606
05886116467109405077541002256983155200055935729725
71636269561882670428252483600823257530420752963450
""".replace('\n', '')
In [24]:
in_list = np.array(list(in_string), dtype=int)
In [95]:
%time
def mult(letters):
accum = 1
for letter in letters:
accum *= int(letter)
return accum
ln = len(in_list)
N = 13
biggest = 0
biggest_i = -1
for i in range(ln-N+1):
product = mult(in_list[i:i+N])
if product > biggest:
biggest_i = i
biggest = product
print(mult(in_list[biggest_i:biggest_i+N]), in_list[biggest_i:biggest_i+N])
In [94]:
%time
N = 13
biggest = 0
biggest_i = -1
i = 0
while i < ln - N:
sub_number = in_list[i:i+N]
for j, sub_sub in enumerate(sub_number):
if sub_sub == 0:
#print("Found 0 at index {:d}".format(i+j))
i += j + 1
break
#if ('0' in sub_number):
else: # no zeros
product = mult(sub_number)
if product > biggest:
biggest_i = i
biggest = product
i = i + 1
#print("Current index: {:d}".format(i))
print(mult(in_list[biggest_i:biggest_i+N]), in_list[biggest_i:biggest_i+N])
In [102]:
%time
N = 13
biggest = 0
biggest_i = -1
product = None #mult(in_list[:N])
i = 0
while i < ln - N:
new_number = in_list[i+N-1]
if new_number == 0:
i = i + N
product = None
else: # not zero
if product is None:
product = mult(in_list[i:i+N])
else:
product /= in_list[i-1]
product *= new_number
if product > biggest:
biggest_i = i
biggest = product
i = i + 1
#print("Current index: {:d}".format(i))
print(mult(in_list[biggest_i:biggest_i+N]), in_list[biggest_i:biggest_i+N])
In [ ]:
for i, letter in enumerate(['a', 'b', 'c']):
print(i, letter)
In [53]:
%time
N = 13
def test_key(ind_letter):
index = ind_letter[0]
letter = ind_letter[1]
return mult(in_string[index:index+N])
biggest_i, _ = max(enumerate(in_string), key=test_key)
print(in_string[biggest_i:biggest_i+N])
In [9]:
target = 10000
for a in range(1, target):
for b in range(a+1, (target - a)//2+1):
c = target - b - a
if a**2 + b**2 == c**2:
print(a, b, c, a*b*c)
In [16]:
# m(m+n) == 5000
# m > n
target = 500
for n in range(1, target):
for m in range(n+1, target):
if m*(m + n) == target:
print(m, n)
print("a = {:d} b = {:d} c = {:d}".format(2*m*n, (m**2 - n**2), (m**2 + n**2)))
In [26]:
def is_prime(number):
if number > 1:
if number == 2:
return True
if number % 2 == 0:
return False
for current in range(3, int(math.sqrt(number) + 1), 2):
if number % current == 0:
return False
return True
else:
return False
def prime_generator(n):
if n % 2 == 0:
i = n-1
else:
i = n
while i > 1:
if is_prime(i):
yield i
i -= 2
if n > 1:
yield 2
In [27]:
sum(prime_generator(2000000))
Out[27]:
In [ ]:
"""
To find all the prime numbers less than or equal to a given integer n by Eratosthenes' method:
Create a list of consecutive integers from 2 through n: (2, 3, 4, ..., n).
Initially, let p equal 2, the smallest prime number.
Enumerate the multiples of p by counting to n from 2p in increments of p, and mark them in the list (these will be 2p, 3p, 4p, ...; the p itself should not be marked).
Find the first number greater than p in the list that is not marked. If there was no such number, stop. Otherwise, let p now equal this new number (which is the next prime), and repeat from step 3.
When the algorithm terminates, the numbers remaining not marked in the list are all the primes below n.
"""
In [22]:
def sieve(N):
list_of_numbers = [False, False, True] + [True]*(N-3)
p = 2
while p*p < N:
for i in range(p+p, N, p):
list_of_numbers[i] = False
# set p to next prime
p += 1
while not list_of_numbers[p]:
p += 1
return np.nonzero(list_of_numbers)[0]
In [28]:
sum(sieve(2000000))
Out[28]:
In [22]:
number_array = np.loadtxt('Data/pe_problem11.txt', dtype='int')
window_size = (4, 4)
row_size, column_size = number_array.shape
In [63]:
largest_product = 0
for r in range(row_size-window_size[0]+1):
for c in range(column_size-window_size[1]+1):
# select subset
subset = number_array[r:r+window_size[0],
c:c+window_size[1]]
horizontal = subset[0]
vertical = subset[:, 0]
diagonal = subset.diagonal()
cross_diagonal = subset.ravel()[3:13:3]
largest_product = max((largest_product,
np.prod(horizontal),
np.prod(vertical),
np.prod(diagonal),
np.prod(cross_diagonal)))
print(largest_product)
In [ ]:
In [26]:
def prime_factorization(n):
factor = 2
factors = defaultdict(int)
while n > 1:
if n % factor == 0:
n /= factor
factors[factor] += 1
else:
break
factor = 3
while n > 1:
if n % factor == 0:
n /= factor
factors[factor] += 1
else:
factor += 2
return factors
In [32]:
def get_num_factors(n):
prime_factors = prime_factorization(n)
return np.prod(np.array(list(prime_factors.values()))+1)
In [31]:
num_factors(28)
Out[31]:
In [36]:
triangle = 0
i = 1
num_factors = 0
while num_factors < 500:
triangle += i
i += 1
num_factors = get_num_factors(triangle)
print(i-1, triangle, num_factors)
In [41]:
numbers = """37107287533902102798797998220837590246510135740250
46376937677490009712648124896970078050417018260538
74324986199524741059474233309513058123726617309629
91942213363574161572522430563301811072406154908250
23067588207539346171171980310421047513778063246676
89261670696623633820136378418383684178734361726757
28112879812849979408065481931592621691275889832738
44274228917432520321923589422876796487670272189318
47451445736001306439091167216856844588711603153276
70386486105843025439939619828917593665686757934951
62176457141856560629502157223196586755079324193331
64906352462741904929101432445813822663347944758178
92575867718337217661963751590579239728245598838407
58203565325359399008402633568948830189458628227828
80181199384826282014278194139940567587151170094390
35398664372827112653829987240784473053190104293586
86515506006295864861532075273371959191420517255829
71693888707715466499115593487603532921714970056938
54370070576826684624621495650076471787294438377604
53282654108756828443191190634694037855217779295145
36123272525000296071075082563815656710885258350721
45876576172410976447339110607218265236877223636045
17423706905851860660448207621209813287860733969412
81142660418086830619328460811191061556940512689692
51934325451728388641918047049293215058642563049483
62467221648435076201727918039944693004732956340691
15732444386908125794514089057706229429197107928209
55037687525678773091862540744969844508330393682126
18336384825330154686196124348767681297534375946515
80386287592878490201521685554828717201219257766954
78182833757993103614740356856449095527097864797581
16726320100436897842553539920931837441497806860984
48403098129077791799088218795327364475675590848030
87086987551392711854517078544161852424320693150332
59959406895756536782107074926966537676326235447210
69793950679652694742597709739166693763042633987085
41052684708299085211399427365734116182760315001271
65378607361501080857009149939512557028198746004375
35829035317434717326932123578154982629742552737307
94953759765105305946966067683156574377167401875275
88902802571733229619176668713819931811048770190271
25267680276078003013678680992525463401061632866526
36270218540497705585629946580636237993140746255962
24074486908231174977792365466257246923322810917141
91430288197103288597806669760892938638285025333403
34413065578016127815921815005561868836468420090470
23053081172816430487623791969842487255036638784583
11487696932154902810424020138335124462181441773470
63783299490636259666498587618221225225512486764533
67720186971698544312419572409913959008952310058822
95548255300263520781532296796249481641953868218774
76085327132285723110424803456124867697064507995236
37774242535411291684276865538926205024910326572967
23701913275725675285653248258265463092207058596522
29798860272258331913126375147341994889534765745501
18495701454879288984856827726077713721403798879715
38298203783031473527721580348144513491373226651381
34829543829199918180278916522431027392251122869539
40957953066405232632538044100059654939159879593635
29746152185502371307642255121183693803580388584903
41698116222072977186158236678424689157993532961922
62467957194401269043877107275048102390895523597457
23189706772547915061505504953922979530901129967519
86188088225875314529584099251203829009407770775672
11306739708304724483816533873502340845647058077308
82959174767140363198008187129011875491310547126581
97623331044818386269515456334926366572897563400500
42846280183517070527831839425882145521227251250327
55121603546981200581762165212827652751691296897789
32238195734329339946437501907836945765883352399886
75506164965184775180738168837861091527357929701337
62177842752192623401942399639168044983993173312731
32924185707147349566916674687634660915035914677504
99518671430235219628894890102423325116913619626622
73267460800591547471830798392868535206946944540724
76841822524674417161514036427982273348055556214818
97142617910342598647204516893989422179826088076852
87783646182799346313767754307809363333018982642090
10848802521674670883215120185883543223812876952786
71329612474782464538636993009049310363619763878039
62184073572399794223406235393808339651327408011116
66627891981488087797941876876144230030984490851411
60661826293682836764744779239180335110989069790714
85786944089552990653640447425576083659976645795096
66024396409905389607120198219976047599490197230297
64913982680032973156037120041377903785566085089252
16730939319872750275468906903707539413042652315011
94809377245048795150954100921645863754710598436791
78639167021187492431995700641917969777599028300699
15368713711936614952811305876380278410754449733078
40789923115535562561142322423255033685442488917353
44889911501440648020369068063960672322193204149535
41503128880339536053299340368006977710650566631954
81234880673210146739058568557934581403627822703280
82616570773948327592232845941706525094512325230608
22918802058777319719839450180888072429661980811197
77158542502016545090413245809786882778948721859617
72107838435069186155435662884062257473692284509516
20849603980134001723930671666823555245252804609722
53503534226472524250874054075591789781264330331690"""
In [45]:
sum([int(n) for n in numbers.split('\n')])
Out[45]:
In [ ]:
'5537376230'
In [51]:
sum([int(n[:12]) for n in numbers.split('\n')])
Out[51]:
In [2]:
@lru_cache(maxsize=None)
def collatz_chain(N):
#print(N)
if N <= 1:
return 1
elif (N % 2 == 0):
return 1 + collatz_chain(N//2)
else:
return 1 + collatz_chain(3*N + 1)
In [3]:
max_chain = 0
max_index = 0
for N in range(1, 1000000):
if collatz_chain(N) > max_chain:
max_chain = collatz_chain(N)
max_index = N
#max_chain = max(max_chain, collatz_chain(N))
In [27]:
print(max_chain, max_index)
In [30]:
tuple1 = (0, 2)
tuple2 = (1, 0)
def second_value(t):
return t[1]
def first_value(t):
return t[0]
sorted([tuple1, tuple2], key=lambda t: t[0])
Out[30]:
In [10]:
second_value(tuple1)
Out[10]:
In [26]:
max_chain = (0, 0)
for N in range(1, 1000000):
max_chain = max(max_chain, (collatz_chain(N), N), key=lambda t: t[0])
In [1]:
['r']*3+['d']*3
Out[1]:
In [4]:
for N in range(2, 6):
print(len(set(itertools.permutations(['r']*N+['d']*N))))
In [9]:
for N in [20]:
print(math.factorial(2*N)/(math.factorial(N)*
math.factorial(N)))
In [16]:
big_num = 2 << 999
In [20]:
def sum_digits(n):
r = 0
while n:
r, n = r + n % 10, n // 10
return r
In [21]:
sum_digits(big_num)
Out[21]:
In [528]:
below_20 = {0: '', 1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five', 6: 'six', 7: 'seven', 8: 'eight', 9: 'nine',
10: 'ten', 11: 'eleven', 12: 'twelve', 13: 'thirteen', 14: 'fourteen', 15: 'fifteen', 16: 'sixteen',
17: 'seventeen', 18: 'eighteen', 19: 'nineteen'}
tens = {2: 'twenty', 3: 'thirty', 4: 'forty', 5: 'fifty', 6: 'sixty', 7: 'seventy', 8: 'eighty', 9: 'ninety'}
total_length = 0
for number in range(1, 1001):
#for number in [342, 115]:
if number == 1000:
hundreds_string = 'one thousand'
tens_string = ''
separator_string = ''
ones_string = ''
else:
tens_place = (number % 100)//10
hundreds_place = (number)//100
if hundreds_place > 0:
hundreds_string = below_20[hundreds_place] + ' hundred'
separator_string = ' and '
else:
hundreds_string = ''
separator_string = ''
if tens_place > 1:
ones_place = number % 10
tens_string = tens[tens_place]
ones_string = below_20[ones_place]
elif tens_place == 1:
ones_place = number % 100
tens_string = ''
ones_string = below_20[ones_place]
elif tens_place == 0:
tens_string = ''
ones_place = number % 10
if ones_place == 0:
separator_string = ''
ones_string = below_20[ones_place]
full_string = "{:s}{:s}{:s} {:s}".format(hundreds_string, separator_string, tens_string, ones_string)
print(full_string, len(full_string.replace(' ', '') ))
total_length += len(full_string.replace(' ', ''))
In [514]:
len("ten hundred".replace(" ", ""))
Out[514]:
In [510]:
len("onethousand")
Out[510]:
In [529]:
total_length
Out[529]:
In [43]:
A = np.array(((3, 0, 0, 0), (7, 4, 0, 0), (2, 4, 6, 0), (8, 5, 9, 3)))
In [44]:
A
Out[44]:
In [52]:
num_rows, num_columns = A.shape
In [60]:
path_sum = A[-1].copy()
In [61]:
for r in range(num_rows - 1, 0, -1): # from num_rows -1 to 1 inclusive
for c in range(0, r): # to r-1 inclusive
path_sum[c] = max(path_sum[c] + A[r - 1, c],
path_sum[c + 1] + A[r - 1, c])
print(path_sum[0])
In [67]:
import pandas as pd
In [78]:
A = pd.read_table('pe_prob18_triangle.txt', delimiter=' ',
names=[str(i) for i in range(15)]).values
In [79]:
num_rows, num_columns = A.shape
path_sum = A[-1].copy()
In [80]:
for r in range(num_rows - 1, 0, -1): # from num_rows -1 to 1 inclusive
for c in range(0, r): # to r-1 inclusive
path_sum[c] = max(path_sum[c] + A[r - 1, c],
path_sum[c + 1] + A[r - 1, c])
print(path_sum[0])
In [17]:
triangle = [
[3],
[7, 4],
[2, 4, 6],
[8, 5, 9, 3]
]
while len(triangle) > 1:
for i in range(len(triangle[-2])):
entry = triangle[-2][i]
triangle[-2][i] = max(entry+triangle[-1][i],
entry+triangle[-1][i+1])
triangle = triangle[:-1]
print(triangle[0])
In [19]:
triangle = [
[75],
[95,64],
[17,47,82],
[18,35,87,10],
[20,4,82,47,65],
[19,1,23,75,3,34],
[88,2,77,73,7,63,67],
[99,65,4,28,6,16,70,92],
[41,41,26,56,83,40,80,70,33],
[41,48,72,33,47,32,37,16,94,29],
[53,71,44,65,25,43,91,52,97,51,14],
[70,11,33,28,77,73,17,78,39,68,17,57],
[91,71,52,38,17,14,91,43,58,50,27,29,48],
[63,66,4,68,89,53,67,30,73,16,69,87,40,31],
[4,62,98,27,23,9,70,98,73,93,38,53,60,4,23]]
while len(triangle) > 1:
for i in range(len(triangle[-2])):
entry = triangle[-2][i]
triangle[-2][i] = max(entry+triangle[-1][i],
entry+triangle[-1][i+1])
triangle = triangle[:-1]
print(triangle)
In [18]:
days_in_months = [31, 28, 31, 30, 31, 30, 31, 30, 31, 30, 31]
Out[18]:
In [10]:
def is_sunday(datetime):
return datetime.weekday() == 6
In [11]:
num_first_sundays = 0
for year in range(1901, 2001):
for month in range(1, 13):
num_first_sundays += is_sunday(datetime.datetime(year=year, month=month, day=1))
print(num_first_sundays)
In [22]:
def factorial1(N): # restricted to positive
if N == 0:
return 1
if N < 0:
raise ValueError("Cannot use negatives")
return N*factorial1(N-1)
def factorial2(N):
holder = 1
for i in range(1, N+1):
holder *= i
return holder
In [25]:
total = 0
for digit in str(factorial1(100)):
total += int(digit)
print(total)
In [ ]:
In [24]:
def prime_factorization(n):
factor = 2
factors = []
while n > 1:
if n % factor == 0:
n /= factor
factors.append(factor)
else:
break
factor = 3
while n > 1:
if n % factor == 0:
n /= factor
factors.append(factor)
else:
factor += 2
return factors
In [25]:
def mul_reduce(l):
tot = 1
for i in l:
tot *= i
return tot
In [31]:
def sum_of_proper_divisors(N):
primes = prime_factorization(N)
primes.append(1)
Nprimes = len(primes)
proper_divisors = set()
for n in range(1, Nprimes+1):
for combo in itertools.combinations(primes, n):
proper_divisors.add(mul_reduce(combo))
d = sum(proper_divisors) - N
return d
In [49]:
N = 10000
pairs = []
for number in range(2, N):
if number in pairs:
continue
d = sum_of_proper_divisors(number)
if number == sum_of_proper_divisors(d) and d != number:
pairs.extend([number, d])
In [50]:
pairs
Out[50]:
In [51]:
sum(pairs)
Out[51]:
In [ ]:
In [530]:
def get_proper_divisors(n):
proper_divisors = []
for i in range(n//2, 0, -1):
if n%i == 0:
proper_divisors.append(i)
return proper_divisors
def get_next_number(N, checked):
for i, c in enumerate(checked[N:]):
if c is False:
return i+N
break
else: # no break
return len(checked)
In [53]:
N = 10000
In [54]:
i = 2
checking = i
checked = [False]*N
checked[0] = True
checked[1] = True
amicable_numbers = []
while checking < N:
sum_of_pds1 = sum(get_proper_divisors(checking))
checked[checking] = True
if (sum_of_pds1 < N) and (not checked[sum_of_pds1]):
sum_of_pds2 = sum(get_proper_divisors(sum_of_pds1))
if checking == sum_of_pds2:
amicable_numbers += [checking, sum_of_pds1] # append
checked[sum_of_pds1] = True
checking = get_next_number(i, checked)
else:
checking = sum_of_pds1
else:
checking = get_next_number(i, checked)
In [56]:
sum(amicable_numbers)
Out[56]:
In [29]:
alphadict = {k: i for i, k in enumerate(string.ascii_uppercase)}
In [16]:
with open('./p022_names.txt') as name_file:
names = name_file.read().replace('"', '').split(',')
In [30]:
name = names[0]
In [36]:
STARTNUM = ord('A')-1 # want 'A' to give 1
In [38]:
Out[38]:
In [48]:
sum(map(lambda arg: sum(map(lambda l: ord(l)-(ord('A')-1), arg[1]))*(arg[0]+1),
enumerate(sorted(open('./p022_names.txt').read().replace('"', '').split(',')))))
Out[48]:
In [85]:
STARTNUM = ord('A')-1 # want 'A' to give 1
total_score = 0
with open('./p022_names.txt') as name_file:
names= name_file.read().replace('"', '').split(',')
for i, name in enumerate(sorted(names)):
name_score = sum(ord(letter)-STARTNUM for letter in name)
total_name_score = name_score*(i+1) # 1 based indexing
total_score += total_name_score
In [86]:
total_score
Out[86]:
In [554]:
def is_abundant(num):
return sum(proper_divs(num)) > num
In [2]:
MUL = int.__mul__
def prime_factors(n):
'Map prime factors to their multiplicity for n'
d = _divs(n)
d = [] if d == [n] else (d[:-1] if d[-1] == d else d)
pf = Counter(d)
return dict(pf)
@lru_cache(maxsize=None)
def _divs(n):
'Memoized recursive function returning prime factors of n as a list'
for i in range(2, int(sqrt(n)+1)):
d, m = divmod(n, i)
if not m:
return [i] + _divs(d)
return [n]
In [3]:
def proper_divs(n):
'''Return the set of proper divisors of n.'''
pf = prime_factors(n)
pfactors, occurrences = pf.keys(), pf.values()
multiplicities = itertools.product(*(range(oc + 1) for oc in occurrences))
divs = {reduce(MUL, (pf**m for pf, m in zip(pfactors, multis)), 1)
for multis in multiplicities}
try:
divs.remove(n)
except KeyError:
pass
return divs or ({1} if n != 1 else set())
In [4]:
proper_divs(28)
Out[4]:
In [576]:
upper_bound = 28123
abundant_numbers = []
for i in range(1, upper_bound):
if is_abundant(i):
abundant_numbers.append(i)
In [584]:
can_be_made = np.zeros(28124, dtype=bool)
In [585]:
for combination in itertools.combinations_with_replacement(abundant_numbers, 2):
try:
can_be_made[int(sum(combination))] = True
except IndexError:
pass
In [586]:
can_be_made[24]
Out[586]:
In [587]:
sum_cannot_be_made = 0
for i, b in enumerate(can_be_made):
if not b:
sum_cannot_be_made += i
print(sum_cannot_be_made)
In [401]:
for i, permutation in enumerate(itertools.permutations(list(range(10)), 10)):
if i == 999999:
print(permutation)
break
In [130]:
def fibonacci(N):
"""
Return fibonacci number, where N must be > 2
"""
f1, f2 = 1, 1
yield 1
yield 1
i = 2
while i < N:
f2, f1 = f1 + f2, f2
yield f2
i += 1
In [134]:
for i, fib in enumerate(fibonacci(10000)):
if len(str(fib)) >= 1000:
print(i+1, fib)
break
else:
print("Not found")
In [24]:
def make_quadratic(a, b):
def _quadratic(n):
return n**2 + a*n + b
return _quadratic
quadratic = make_quadratic(1, 41)
In [28]:
def prime_chain(a, b):
quadratic = make_quadratic(a, b)
N = 0
while is_prime(quadratic(N)):
N += 1
return N
In [35]:
max_chain = (0, 0, 0)
for a in range(-999, 1000):
for b in range(-1000, 1001):
max_chain = max(max_chain, (prime_chain(a, b), a, b), key=lambda x: x[0])
print(max_chain)
In [36]:
-61*971
Out[36]:
In [53]:
unique_numbers = set()
for a in range(2, 101):
for b in range(2, 101):
unique_numbers.add(a**b)
print(len(unique_numbers))
In [369]:
power = 5
accum = 0
for i in range(2, 1000000):
str_num = str(i)
sum_ = sum([int(digit)**power for digit in str_num])
if sum_ == i:
accum += i
In [370]:
print(accum)
In [79]:
def is_pandigital(number):
return Counter(number) == Counter(['1', '2', '3', '4', '5', '6', '7', '8', '9'])
In [90]:
pandigital_products = set()
for multiplicand in range(10000):
for multiplier in range(100):
product = multiplicand * multiplier
if is_pandigital(list(str(multiplicand)) +
list(str(multiplier)) +
list(str(product))):
pandigital_products.add(product)
print(sum(pandigital_products))
In [91]:
pandigital_products
Out[91]:
In [5]:
MUL = int.__mul__
def prime_factors(n):
'Map prime factors to their multiplicity for n'
d = _divs(n)
d = [] if d == [n] else (d[:-1] if d[-1] == d else d)
pf = Counter(d)
return dict(pf)
@lru_cache(maxsize=None)
def _divs(n):
'Memoized recursive function returning prime factors of n as a list'
for i in range(2, int(sqrt(n)+1)):
d, m = divmod(n, i)
if not m:
return [i] + _divs(d)
return [n]
In [6]:
def proper_divs(n):
'''Return the set of proper divisors of n.'''
pf = prime_factors(n)
pfactors, occurrences = pf.keys(), pf.values()
multiplicities = itertools.product(*(range(oc + 1) for oc in occurrences))
divs = {reduce(MUL, (pf**m for pf, m in zip(pfactors, multis)), 1)
for multis in multiplicities}
try:
divs.remove(n)
except KeyError:
pass
return divs or ({1} if n != 1 else set())
In [15]:
numerator = 49
denomenator = 98
largest_common = max(proper_divs(numerator).intersection(proper_divs(denomenator)))
numerator/largest_common, denomenator/largest_common
Out[15]:
In [17]:
49/98
Out[17]:
In [371]:
def factorial(n):
accum = 1
for i in range(1, n+1):
accum *= i
return accum
In [391]:
factorials = [factorial(i) for i in range(10)]
In [392]:
factorials
Out[392]:
In [393]:
for num in range(3, 1000000):
str_num = str(num)
sum_ = sum([factorials[int(digit)] for digit in str_num])
if sum_ == num:
print(num)
In [394]:
145+40585
Out[394]:
In [ ]:
def is_prime(number, list_of_primes):
if number > 1:
for old_prime in list_of_primes:
if old_prime**2 > number: # if we have gotten past the point of no return
return True
if number % old_prime == 0:
return False
raise RuntimeError("Should not have gotten here")
else:
return False
In [64]:
n = 11
prime_count = 0
truncatable_primes = []
list_of_primes = [2, 3, 5, 7] # make a list of length n
number = 11
while(prime_count < n):
if is_prime(number, list_of_primes): # if number is prime
list_of_primes.append(number)
# left -> right
num_str = str(number)
for i in range(len(num_str)):
if not is_prime(int(num_str[i:]), list_of_primes):
break
else: # no break must be truncatable from left-> right
# Check right -> left
for i in range(len(num_str)):
if not is_prime(int(num_str[:len(num_str)-i]), list_of_primes):
break
else: # no break
truncatable_primes.append(number)
prime_count += 1
number += 2
In [66]:
sum(truncatable_primes)
Out[66]:
In [38]:
pandigitals = [i for i in itertools.permutations('123456789')]
In [109]:
N = 500
Ns = np.arange(1, 2001)
ints = np.arange(1, 11)
numbers = Ns[:, None]*ints[None, :]
In [91]:
def is_pandigital(s):
return Counter(s) == Counter('123456789')
In [110]:
largest_pandigital = (0, 0, 0)
for i, number_list in enumerate(map(lambda a: ["".join(a.astype('str')[:i])
for i in range(1, len(a.astype('str')))],
numbers)):
for j, number in enumerate(number_list):
if is_pandigital(number):
largest_pandigital = max(largest_pandigital, (int(number), i, j),
key=lambda t: t[0])
In [114]:
9786*2
Out[114]:
In [111]:
largest_pandigital
Out[111]:
In [ ]:
978654312
In [28]:
# Empty to start
digits = {1: 0, 10: 0, 100: 0, 1000: 0, 10000: 0, 100000: 0, 1000000: 0}
num = 0
i = 0
while i < 1000000:
num += 1
for digit in str(num):
i += 1
if i in digits:
digits[i] = int(digit)
In [30]:
reduce(int.__mul__, digits.values(), 1)
Out[30]:
In [7]:
def is_prime(number):
if number > 1:
if number == 2:
return True
if number % 2 == 0:
return False
for current in range(3, int(math.sqrt(number) + 1), 2):
if number % current == 0:
return False
return True
return False
In [2]:
sum(range(1, 10)) # a 9 digit pandigital is never prime
Out[2]:
In [3]:
sum(range(1, 9)) # neither is a 8 digit
Out[3]:
In [6]:
for N in range(2, 10):
print(N, sum(range(1, N)), sum(range(1, N)) % 3 == 0)
In [18]:
reduce(str.__add__, ('1', '2', '3'))
Out[18]:
In [8]:
#digits 1-7 give a possibly prime pandigital
largest_pandigital = 7654321
In [23]:
for i in itertools.permutations(str(largest_pandigital)):
i = int(reduce(str.__add__, i))
if is_prime(i):
print(i)
break
else:
print('None found')
In [19]:
str(sum(i**i for i in range(1, 1001)))[-10:]
Out[19]:
In [2]:
def is_prime(number):
if number > 1:
if number == 2:
return True
if number % 2 == 0:
return False
for current in range(3, int(math.sqrt(number) + 1), 2):
if number % current == 0:
return False
return True
return False
In [3]:
def prime_generator(n):
if n % 2 == 0:
i = n-1
else:
i = n
while i > 1:
if is_prime(i):
yield i
i -= 2
if n > 1:
yield 2
In [4]:
prime_list = np.array([prime for prime in prime_generator(10000) if prime > 999])
In [17]:
class Found(Exception): pass
try:
for incr in range(2, 10000, 2):
for prime in prime_list:
if (prime + incr) in prime_list:
if (prime + 2*incr) in prime_list:
if Counter(str(prime)) == Counter(str(prime + incr)) and\
Counter(str(prime)) == Counter(str(prime + incr*2)):
raise Found
except Found:
print(prime, prime + incr, prime + incr*2)
In [16]:
(Counter(str(1487)) == Counter(str(1487 + 3330))) and (Counter(str(1487)) == Counter(str(1487 + 3330*2)))
Out[16]:
In [177]:
# need to also include the number 1
number_of_powerful_digits = 1 # 1^1 = 1
for power in range(1, 50):
number = str(2**power)
if len(number) == power:
number_of_powerful_digits += 1
#print("{number} = {num}^{power}".format(number=number,
# num=2,
# power=power))
elif len(number) > power:
break # out of outer loop - will never get smaller
for num in range(3, 20): # don't include 1 so that we can check if we have gone too far
number = str(num**power)
if len(number) == power:
#print("{number} = {num}^{power}".format(number=number,
# num=num,
# power=power))
number_of_powerful_digits += 1
elif len(number) > power:
break # out of inner loop - will never get smaller
print(number_of_powerful_digits)
In [118]:
triangle = []
with open('p067_triangle.txt', 'r') as f:
for line in f.readlines():
triangle.append([int(n) for n in line.replace('\n', '').split(' ')])
In [119]:
while len(triangle) > 1:
for i in range(len(triangle[-2])):
entry = triangle[-2][i]
triangle[-2][i] = max(entry+triangle[-1][i],
entry+triangle[-1][i+1])
triangle = triangle[:-1]
print(triangle[0])
In [39]:
sums = defaultdict(int)
for n in range(1, 2000):
for m in range(n+1, 2000):
a, b, c = m**2 - n**2, 2*m*n, m**2 + n**2
sums[a+b+c] += 1
In [36]:
count = 0
for _sum, val in sums.items():
if _sum <= 1500000 and val == 1:
count += 1
print(count)
In [49]:
sums = defaultdict(list)
for n in range(1, 1000):
for m in range(n+1, 1000):
for k in range(1, 100):
a, b, c = k*(m**2 - n**2), k*(2*m*n), k*(m**2 + n**2)
if set((a, b, c)) not in sums[a+b+c]:
sums[a+b+c].append(set((a, b, c)))
In [51]:
count = 0
for _sum, val in sums.items():
if _sum <= 1500000 and len(val) == 1:
count += 1
print(count)
In [59]:
sums[120]
Out[59]:
In [6]:
sums = defaultdict(list)
for combination in itertools.combinations(range(1, 30), 2):
m, n = combination
if n > m:
m, n = n, m
for k in range(1, 20):
a, b, c = k*(m**2 - n**2), k*(2*m*n), k*(m**2 + n**2)
sums[a+b+c].append((a, b, c))
In [7]:
sums[120]
Out[7]:
In [2]:
@lru_cache(maxsize=None)
def square_digits(num):
return sum([int(d)**2 for d in str(num)])
In [7]:
get_to_89 = 0
for num in range(1, 10000000):
while (num != 1) and (num != 89):
num = square_digits(num)
if num == 89:
get_to_89 += 1
In [8]:
get_to_89
Out[8]:
In [5]:
last_ten = (2**7830457)%(10**10)
last_ten *= 28433
last_ten %= (10**10)
last_ten += 1
print(last_ten)
In [191]:
word_list = []
with open('p098_words.txt') as words:
for word in words.readline().split(','):
word_list.append(word.replace('"', ''))
In [213]:
def is_anagram(word1, word2):
return Counter(word1) == Counter(word2)
In [250]:
word_length = defaultdict(list)
for word in word_list:
word_length[len(word)].append(word)
In [268]:
plt.bar([i for i in word_length.keys()], [len(val) for val in word_length.values()])
Out[268]:
In [273]:
anagrams = []
for words in word_length.values():
checked = [False]*len(words)
for i, word in enumerate(words):
if checked[i]:
continue # already checked this word
anagram_list = []
for j, other_word in enumerate(words):
if not checked[j] and is_anagram(word, other_word) and other_word != word:
anagram_list.append(other_word)
checked[j] = True
if len(anagram_list) > 0:
anagram_list.append(word)
anagrams.append(anagram_list)
checked[i] = True
In [286]:
anagrams_by_length = defaultdict(list)
for words in anagrams:
word_length = len(words[0])
anagrams_by_length[word_length].append(words)
In [291]:
def get_letter_values(word, number):
letter_values = {}
for letter, num in zip(word, number):
if letter in letter_values:
if num != letter_values[letter]:
return None
else:
letter_values[letter] = num
return letter_values
In [307]:
largest_square = int(math.sqrt(10**(max(anagrams_by_length.keys())+1)))
square_numbers = [i*i for i in range(largest_square)]
In [312]:
found_square_numbers = []
for square_number in square_numbers:
square_str = str(square_number)
number_length = len(square_str)
try:
anagram_list = anagrams_by_length[number_length]
except KeyError:
continue
for words in anagram_list: # get the words that are anagrams with each other
word = words[0]
other_word = words[1]
if len(set(word)) != len(set(square_str)):
break
letter_values = get_letter_values(word, square_str)
if letter_values is None:
break # break out of this loop -- there is not a match between this permutation and letters
number = 0
for i, letter in enumerate(reversed(word)):
number += int(letter_values[letter])*(10**i)
sqrt = np.sqrt(number)
if sqrt - np.floor(sqrt) != 0:
break
other_number = 0
for i, letter in enumerate(reversed(other_word)):
other_number += int(letter_values[letter])*(10**i)
other_sqrt = np.sqrt(other_number)
if other_sqrt - np.floor(other_sqrt) == 0: # both numbers are perfect squares
found_square_numbers.append(number)
found_square_numbers.append(other_number)
print(word, number, sqrt, other_word, other_number, other_sqrt)
In [474]:
def is_pandigital(number):
return all([str(i) in number for i in range(1, 10)])
def is_pandigital2(number):
return set(number) == set(['1', '2', '3', '4', '5', '6', '7', '8', '9'])
In [479]:
def fibonacci_closed(N):
return ((1 + math.sqrt(5))**N - (1 - math.sqrt(5))**N )/(2**N * math.sqrt(5))
In [485]:
fibonacci_closed(100)
Out[485]:
In [478]:
for i, number in tqdm.tqdm(enumerate(fibonacci(1000000))):
str_number = str(number)
if len(str_number) > 8:
if is_pandigital2(str_number[:9]) and is_pandigital2(str_number[-9:]):
print(i+1, number)
break
In [464]:
%time str(12343243)[-9:]
Out[464]:
In [470]:
def func1():
return str(number)[-9:]
def func2():
return str(number % (10**9))
In [472]:
%timeit func2
In [473]:
%timeit func1
In [154]:
def is_bouncing(str_num):
increasing = True
decreasing = True
bouncing = False
for digit, next_digit in zip(str_num[:-1], str_num[1:]):
if digit > next_digit:
increasing = False
elif digit != next_digit:
decreasing = False
if (not increasing) and (not decreasing):
bouncing = True
break
return bouncing
In [169]:
target = 0.99 # percentage of bouncing numbers
num_bouncing = 0
i = 0
percentage = 0
while percentage < target:
i += 1
if is_bouncing(str(i)):
num_bouncing += 1
percentage = num_bouncing/i
print(percentage, i)
In [96]:
def is_prime(number):
if number > 1:
if number == 2:
return True
if number % 2 == 0:
return False
for current in range(3, int(math.sqrt(number) + 1), 2):
if number % current == 0:
return False
return True
return False
def prime_generator(n):
if n % 2 == 0:
i = n-1
else:
i = n
while i > 1:
if is_prime(i):
yield i
i -= 2
if n > 1:
yield 2
In [113]:
digits = list(range(1, 10))
for combo in itertools.combinations(digits, 8):
if sum(combo) % 3 != 0:
missing = [i for i in digits if i not in combo]
print(combo, missing)
In [110]:
12456789 % 3
Out[110]:
In [98]:
def odds_n_evens(n):
if n < 10:
even = n % 2 == 0
return (int(not even), int(even))
n = str(n)
ln = len(n)
odds = 0
evens = 0
for digit1, digit2 in zip(n[:ln//2], n[ln//2:]):
even = int(digit1) % 2 == 0
evens += even
odds += (not even)
even = int(digit2) % 2 == 0
evens += even
odds += (not even)
return (odds, evens)
In [8]:
def odds_n_evens_ends(n):
n = str(n)
return (int(n[0]) % 2 == 0) != (int(n[-1]) % 2 == 0)
In [2]:
def reverse_number(n):
return int(str(n)[::-1])
def all_odd(n):
for digit in str(n):
if int(digit) % 2 == 0:
return False
return True
def is_reversable(n):
if n % 10 == 0:
return False
return all_odd(n+reverse_number(n))
In [122]:
%%timeit
is_reversable(8452354)
In [123]:
%%timeit
odds_n_evens_ends(8452354)
In [15]:
def func1(N):
num_reversable = 0
for n in range(10, N):
num_reversable += is_reversable(n)
print(num_reversable)
def func2(N):
reversable = {}
for n in range(10, N):
if n not in reversable:
if n % 10 != 0:
rev = reverse_number(n)
result_all_odd = all_odd(n + rev)
reversable[n] = result_all_odd
reversable[rev] = result_all_odd
else:
reversable[n] = False
print(sum(reversable.values()))
In [40]:
def func3(N):
reversable = {}
#num_reversable = 0
for n in range(10, N, 10):
base = (10**math.floor(math.log10(n)))
rev_base = reverse_number(n)
for i in range(1, 10):
if n+i not in reversable:
rev = rev_base + base*i
result_all_odd = all_odd(n+i + rev)
#num_reversable += result_all_odd
reversable[n+i] = result_all_odd
reversable[rev] = result_all_odd
#else:
#num_reversable += reversable[n+i]
print(sum(reversable.values()))
In [14]:
for N in [1000, 10000, 100000]:
%time func1(N)
In [44]:
for N in [1000, 10000, 100000]:
%time func2(N)
In [45]:
for N in [1000, 10000, 100000]:
%time func3(N)
In [10]:
pandigitals = np.array([1023456789, 1023456798, 1023456879, 1023456897, 1023456978, 1023456987, 1023457689,
1023457698, 1023457869, 1023457896, 1023457968, 1023457986, 1023458679, 1023458697,
1023458769, 1023458796, 1023458967, 1023458976, 1023459678, 1023459687])
In [171]:
def change_base(number, orig_base, new_base):
ln = len(number) - 1
new_num = number_to_base(number[0]*(orig_base**(ln-0)), new_base)
for i, digit in enumerate(number[1:]):
new_num_ = number_to_base(digit*(orig_base**(ln-(i+1))), new_base)
next_digit = 0
for i, (digit_1, digit_2) in enumerate(zip(reversed(new_num), reversed(new_num_))):
_next_digit, cur_digit = divmod(digit_1 + digit_2, new_base)
new_num[-(i+1)] = cur_digit + next_digit
next_digit = _next_digit
return new_num
In [176]:
%time change_base([1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1], 2, 4)
Out[176]:
In [175]:
%time number_to_base(to_base_10([1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 0, 0, 1, 1], 2), 4)
Out[175]:
In [173]:
print(number_to_base(235235, 2))
print(number_to_base(235235, 4))
In [31]:
def number_to_base(n, b):
if n == 0:
return [0]
digits = []
while n:
digits.append(int(n % b))
n //= b
return digits[::-1]
In [32]:
def to_base_10(num, base):
output = 0
for i, digit in enumerate(reversed(num)):
output += digit * (base**i)
return output
In [33]:
def is_pandigital(num, base):
for i in range(base):
if i not in num:
return False
return True
In [35]:
base = 12
starting = base**(base - 1) + sum([d*base**(base - 1 - d) for d in range(2, base)])
In [207]:
%%time
base = 10
super_pandigital = []
starting = base**(base - 1) + sum([d*base**(base - 1 - d) for d in range(2, base)])
starting = number_to_base(starting, base)
for i, num in enumerate(itertools.permutations(starting, base)):
if (len(super_pandigital) > 9):
break
for b in range(base, 1, -1):
_num = number_to_base(to_base_10(num, base), b)
#print(_num, is_pandigital(_num, b))
if not is_pandigital(_num, b):
break
else: # no break
super_pandigital.append(num)
In [36]:
number_to_base(to_base_10(starting, 10), 12)
In [202]:
super_pandigital
Out[202]:
In [203]:
i
Out[203]:
In [191]:
reduce(int.__mul__, range(1, base+1), 1)
Out[191]:
In [180]:
sum(to_base_10(num, 10) for num in super_pandigital)
Out[180]:
In [88]:
len(super_pandigital)
Out[88]:
In [195]:
np.cumsum(range(13))
Out[195]:
In [ ]: