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project_euler.py
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project_euler.py
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import numpy as np
import matplotlib.pyplot as plt
import math
import operator
import itertools
import csv
import collections
import decimal
import sympy
import decimal
import fractions
import scipy
import euler_utils as utils
def problem_1():
return sum(xrange(3,1000,3)) + sum(xrange(5,1000,5)) - sum(xrange(15,1000,15))
def problem_2():
result_sum = 0
for num in utils.fibonnaci():
if num > 4000000:
return result_sum
if num %2 == 0:
result_sum += num
def problem_3():
return utils.prime_factorize(600851475143)[-1]
def problem_4():
vect_palindrome = np.vectorize(utils.is_palindrome)
domain = np.arange(1,1000)
all = np.outer(domain, domain)
usable = vect_palindrome(all)
return np.max(all[usable])
def problem_5(num = 20):
"""# 2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.
What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?
"""
primes = utils.get_primes_below(num)
factors = [pow(prime, int(math.log(num)/math.log(prime))) for prime in primes]
value = reduce(operator.mul, factors, 1)
return value
def problem_6():
return sum(np.arange(1, 101))**2 - sum(np.arange(1, 101)**2)
def problem_7():
"""By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
What is the 10 001st prime number?"""
primes = utils.get_primes_below(1000000)
return primes[10000]
def problem_8():
"""Find the greatest product of five consecutive digits in the 1000-digit number."""
num = '7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450'
window_length = 5
def get_prod(num, indx1, indx2):
prod = 1
for i in range(indx1, indx2):
prod *= int(num[i])
return prod
max_val = 0
for i in range(4, len(num)):
val = get_prod(num, i-window_length+1, i+1)
if val > max_val:
max_val = val
return max_val
# TODO, understand the better way to do this (non cheater)
def problem_9():
"""A Pythagorean triplet is a set of three natural numbers, a < b < c, for which,
a^2 + b^2 = c^2
For example, 3^2 + 4^2 = 9 + 16 = 25 = 5^2.
There exists exactly one Pythagorean triplet for which a + b + c = 1000.
Find the product abc."""
def sol_1(real):
b = -.5*real - .5*np.sqrt(real**2 + 2000*real - 1000000) + 500
a = 1000.*(real + np.sqrt(real**2 + 2000*real - 1000000))/(real + np.sqrt(real**2 + 2000*real - 1000000) + 1000)
c = real
return [a, b, c]
def sol_2(real):
b = -.5*real + .5*np.sqrt(real**2 + 2000*real - 1000000) + 500
a = 1000.*(real - np.sqrt(real**2 + 2000*real - 1000000))/(real - np.sqrt(real**2 + 2000*real - 1000000) + 1000)
c = real
return [a, b, c]
def condition(numbers):
worked = True
for n in numbers:
if n%1 != 0 or n < 1:
worked = False
return worked
answers = []
for real in xrange(1000):
option = sol_1(real)
if condition(option):
print option
return reduce(operator.mul, option)
def problem_10():
"""The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
Find the sum of all the primes below two million."""
return sum(utils.get_primes_below(2000000))
def problem_11():
"""find largest product of 4 numbers in given grid going up, down, lr, diag"""
grid = np.array([[8, 2, 22, 97, 38, 15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8],
[49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 4, 56, 62, 0],
[81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 3, 49, 13, 36, 65],
[52, 70, 95, 23, 4, 60, 11, 42, 69, 24, 68, 56, 1, 32, 56, 71, 37, 2, 36, 91],
[22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80],
[24, 47, 32, 60, 99, 03, 45, 2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50],
[32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70],
[67, 26, 20, 68, 2, 62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21],
[24, 55, 58, 5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
[21, 36, 23, 9, 75, 0, 76, 44, 20, 45, 35, 14, 0, 61, 33, 97, 34, 31, 33, 95],
[78, 17, 53, 28, 22, 75, 31, 67, 15, 94, 3, 80, 4, 62, 16, 14, 9, 53, 56, 92],
[16, 39, 5, 42, 96, 35, 31, 47, 55, 58, 88, 24, 0, 17, 54, 24, 36, 29, 85, 57],
[86, 56, 0, 48, 35, 71, 89, 7, 5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
[19, 80, 81, 68, 5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 4, 89, 55, 40],
[4, 52, 8, 83, 97, 35, 99, 16, 7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
[88, 36, 68, 87, 57, 62, 20, 72, 3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
[4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76, 36],
[20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 4, 36, 16],
[20, 73, 35, 29, 78, 31, 90, 1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 5, 54],
[1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 1, 89, 19, 67, 48]])
def largest_multiplication(grid, i, j):
# only do right, down, and down diag
best = 0
prod = 1
if i + 3 <= 19:
# down
for elem in grid[i:i+4, j]:
prod *= elem
if prod > best:
best = prod
prod = 1
if j + 3 <= 19:
# right
for elem in grid[i, j:j+4]:
prod *= elem
if prod > best:
best = prod
prod = 1
if i + 3 <= 19 and j + 3 <= 19:
# diag down right
for offset in range(4):
prod *= grid[i+offset, j+offset]
if prod > best:
best = prod
prod = 1
if i + 3 <= 19 and j - 3 >= 0:
# diag down left
for offset in range(4):
prod *= grid[i+offset, j-offset]
if prod > best:
best = prod
return best
bests = np.zeros(grid.shape)
for i in xrange(20):
for j in xrange(20):
cur = largest_multiplication(grid, i, j)
bests[i,j] = cur
return np.max(bests)
# TODO: this is brute force
def problem_12():
def get_natural_num_sum(n):
return (n**2 + n)/2
n = 1
while True:
val = len(utils.get_divizors(get_natural_num_sum(n)))
if val > 500:
return get_natural_num_sum(n)
n += 1
def problem_13():
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]
num_sum = reduce(operator.add, numbers)
return int(str(num_sum)[:10])
def problem_14():
def next(n):
if n%2 == 0:
return n/2
else:
return 3*n + 1
length_dict = {1:1}
def get_length(n):
if n in length_dict:
return length_dict[n]
length = 1 + get_length(next(n))
length_dict[n] = length
return length
longest_length = 0
for i in xrange(1, 1000000):
length = get_length(i)
if length > longest_length:
longest_length = length
longest_num = i
return longest_num
def problem_15():
return math.factorial(40)/(math.factorial(20)*math.factorial(20))
def problem_16():
num = str(2**1000)
fun = lambda x, y: int(x)+int(y)
return reduce(fun, num)
def find_max_triangle_path(triangle):
def get_parents(indx, row):
left = right = None
if indx - 1 >= 0:
left = indx - 1
if indx + 1 <= row:
right = indx
return (left, right)
for r_indx, row in enumerate(triangle[1:]):
for e_indx, elem in enumerate(row):
parents = get_parents(e_indx, r_indx + 1)
parents = [triangle[r_indx][p] for p in parents if p is not None]
row[e_indx] += max(parents)
return max(triangle[-1])
def problem_17():
below_20 = {0: 'zero', 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 = {1: 'ten', 2:'twenty', 3:'thirty', 4:'forty', 5:'fifty', 6:'sixty', 7:'seventy', 8:'eighty', 9:'ninety'}
hundred = 'hundred'
thousand = 'thousand'
def get_2_digit(n, is_suffix = False):
tens_digit = n/10
ones_digit = n%10
if is_suffix and n == 0:
return ''
if is_suffix:
name = ' and '
else:
name = ''
if n < 20:
return name + below_20[n]
if ones_digit == 0:
return name + tens[tens_digit]
else:
return name + tens[tens_digit] + ' ' + below_20[n%10]
def get_3_digit(n, is_suffix = False):
if n < 100:
return get_2_digit(n, is_suffix)
hundreds = n/100
tens = n%100
if is_suffix:
name = ' '
else:
name = ''
return name + below_20[hundreds] + ' ' + hundred + get_2_digit(n%100, True)
def get_6_digit(n):
if n < 1000:
return get_3_digit(n, False)
thousands = n/1000
hundreds = (n%1000)/100
# if hundreds == 0:
# return get_3_digit(thousands) + ' thousand ' + 'and ' + get_3_digit(n%1000, True)
# else:
return get_3_digit(thousands) + ' thousand' + get_3_digit(n%1000, True)
letter_sum = 0
for i in xrange(1, 1001):
letter_sum += len(get_6_digit(i).replace(' ', ''))
return letter_sum
def problem_18():
triangle = [[75],
[95, 64],
[17, 47, 82],
[18, 35, 87, 10],
[20, 04, 82, 47, 65],
[19, 01, 23, 75, 03, 34],
[88, 02, 77, 73, 07, 63, 67],
[99, 65, 04, 28, 06, 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, 04, 68, 89, 53, 67, 30, 73, 16, 69, 87, 40, 31],
[04, 62, 98, 27, 23, 9 , 70, 98, 73, 93, 38, 53, 60, 04, 23]]
return find_max_triangle_path(triangle)
def problem_19():
# 1 Jan 1900 was a Monday.
# How many Sundays fell on the first of the month during the twentieth century (1 Jan 1901 to 31 Dec 2000)?
def get_month_length_given_year(month_index, year):
# Thirty days has September,
# April, June and November.
# All the rest have thirty-one,
# Saving February alone,
# Which has twenty-eight, rain or shine.
# And on leap years, twenty-nine.
def is_leap_year(year):
# A leap year occurs on any year evenly divisible by 4, but not on a century unless it is divisible by 400.
# return year%4 == 0 and not (year% 100 == 0 and not year%400 == 0)
return year%4 == 0 and not (year% 100 == 0 and not year%400 == 0)
if month_index == 1:
# handle February case
if is_leap_year(year):
return 29
else:
return 28
month_lengths = [31, None, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
return month_lengths[month_index]
num_suns = 0
day_indx = 1 #since this is all starting on a monday, and I need to be zero indexed on sundays
for year in xrange(1901, 2001):
for month in xrange(12):
day_indx += get_month_length_given_year(month, year)
if (day_indx + 1)%7 == 0: #+1 is to check first of next month instead of last of this one
num_suns += 1
if (day_indx+1)%7 == 0:
num_suns -= 1 #un_count the first day of the 21st century if need be
return num_suns
def problem_20():
return reduce(operator.add, [int(x) for x in str(math.factorial(100))])
def problem_21():
start_num = 3
factors = [utils.get_divizors(x, True) for x in xrange(start_num, 10000)]
factor_sum = [reduce(operator.add, factor) for factor in factors]
# padd to make indexing easier
for i in range(start_num):
factor_sum.insert(0, 0)
amicables = set()
for indx in xrange(start_num, 10000):
if factor_sum[indx] > 9999 or factor_sum[indx] < 0:
continue
if indx == factor_sum[factor_sum[indx]] and indx != factor_sum[indx]:
amicables.update([indx, factor_sum[factor_sum[indx]]])
return reduce(operator.add, amicables)
def problem_22():
def convert_letter_to_alphabet_index(ch):
return ord(ch.upper()) - 64
def get_score_from_name(name, indx):
return indx * reduce(operator.add, [convert_letter_to_alphabet_index(ch) for ch in name])
with open('euler_resources/names.txt', 'rb') as f:
reader = csv.reader(f, delimiter = ',')
names_list = [row for row in reader]
names_list = names_list[0] #there is only 1 row
names_list.sort()
scores_list = [get_score_from_name(name, indx + 1) for indx, name in enumerate(names_list)] #they want index 1 indexed
return reduce(operator.add, scores_list)
def problem_23():
start_num = 3
factor_sums = [reduce(operator.add, utils.get_divizors(x, True)) for x in xrange(start_num, 28123)]
ab_set = set([i + start_num for i,f_sum in enumerate(factor_sums) if f_sum > i + 3])
ab_sums = set(reduce(operator.add, x) for x in itertools.combinations(ab_set, 2))
ab_sums = ab_sums.union(set([x*2 for x in ab_set]))
answers = set(xrange(28124)).difference(ab_sums)
return reduce(operator.add, answers)
def problem_24():
perms = itertools.permutations(range(10),10)
for indx, val in enumerate(perms):
if indx == 1000000 - 1:
return int(reduce(operator.add, [str(x) for x in val]))
def problem_25():
for i, fib in enumerate(utils.fibonnaci()):
if len(str(fib)) >= 1000:
return i
def count_decimal_digits_in_divizor(n):
decimal.getcontext().prec = 100
digits = str(decimal.Decimal(1)/decimal.Decimal(n))[2:]
count = collections.Counter(digits)
if len(digits) < 100:
return count, 1
else :
counts = np.array([count[x] for x in count])
max_val = max(counts)
return count, sum(counts >= max_val - 4)
def problem_26():
def get_n_decimal_digits(n, num, den):
decimal.getcontext().prec = n
digits = str(decimal.Decimal(num)/decimal.Decimal(den))[2:]
return digits
max_length = 0
decimal_count = 1000
for i in xrange(1,1000):
digits = get_n_decimal_digits(decimal_count, 1, i)
if len(digits) < decimal_count:
continue
worked = False
length_guess = 1
while(not worked):
for j in xrange(10, decimal_count-10 - length_guess):
if digits[j] != digits[j+length_guess]:
length_guess += 1
break
else:
worked = True
if length_guess > max_length:
max_length = length_guess
best_val = i
return best_val
def problem_27():
max_n_estimate = 200
primes = set(utils.get_primes_below(max_n_estimate**2 + max_n_estimate*1000 + 1000))
b_primes = utils.get_primes_below(1000)
best_count = 0
best_a = 0
best_b = 0
for a in xrange(-999,1000):
for b in b_primes:
n = 1
while(True):
if (n**2 + n*a + b) in primes:
n+=1
else:
break
if n > best_count:
best_count = n
best_a = a
best_b = b
return best_a * best_b
def problem_28():
results = np.array([[1,1,1,1]])
start = np.array([0,0,0,0])
for i, _ in enumerate(xrange(3, 1002, 2)):
increase = np.array([0,-2,-4,-6]) + 8*(i+1)
results = np.vstack([results, results[-1,:] + increase])
return np.sum(results[1:,:]) + 1
# def problem_29(): # Doesn't work
# base_max = 100
# exp_max = 100
# uesful_exp_list = []
# for i in xrange(2,base_max+1):
# exponents = range(2, exp_max+1)
# remove_exp1 = 2
# while i**remove_exp1 <= base_max:
# remove_exp2 = remove_exp1*2
# while remove_exp2 <= exp_max:
# if remove_exp2 in exponents:
# exponents.remove(remove_exp2)
# print "removed exp ", remove_exp2, " from ", i
# remove_exp2 += remove_exp1
# remove_exp1 += 1
# uesful_exp_list.append(exponents)
# # return sum([len(x) for x in uesfull_exp_list])
# huge_set = set()
# for indx, row in enumerate(uesful_exp_list):
# for elem in row:
# if (indx+2)**elem in huge_set:
# print "base = ", indx+2, " exp = ", elem
# huge_set.add((indx+2)**elem)
# return huge_set
def problem_29(): #brute, ouch
massive_set = set()
for b in xrange(2,101):
for e in xrange(2,101):
massive_set.add(b**e)
return len(massive_set)
def problem_30(): #brute
results = []
for i in xrange(2, 200000): #picked arbitrarily, got lucky
nums = [int(x)**5 for x in str(i)]
if sum(nums) == i:
results.append(i)
return sum(results)
def problem_31():
def make_change_options(currency_values, n, post_fix = []):
"""Makes change given an array of sorted currency values and an int"""
results = []
if len(currency_values) == 1:
return [n//currency_values[0]] + post_fix
for i in xrange(0, n//currency_values[-1] + 1):
post_fix_copy = post_fix[:]
results.extend(make_change_options(currency_values[:-1], n - i * currency_values[-1], [i] + post_fix_copy))
return results
currency = [1, 2, 5, 10, 20, 50, 100, 200]
amount = 200
return len(np.array(make_change_options(currency, amount)).reshape(-1, len(currency)))
def problem_32():
a = 1
b = 1
prod_set = set()
while(True):
# a incrementing logic
b = a
while(True):
# b incrementing logic
if utils.is_pandigital([a, b, a*b]):
prod_set.add(a*b)
b += 1
if len(str(a) + str(b) + str(a*b)) > 9:
break
a += 1
if len(str(a)*2 + str(a*a)) > 9:
break
return sum(prod_set)
def problem_33():
results = []
for num in xrange(10,99):
for den in xrange(num+1,100):
if num %10 == 0 and den %10 == 0:
continue
ns = collections.Counter(str(num))
ds = collections.Counter(str(den))
if len(ns - ds) == 1 and (ns-ds).values()[0] == 1:
n1 = int((ns-ds).keys()[0])
d1 = int((ds-ns).keys()[0])
if d1 == 0:
continue
if float(n1)/d1 == float(num)/den:
results.append([num, den])
# results now contains all the numerator and denominator pairs, just need to multiply and reduce
results = np.array(results)
final_frac = np.prod(results, 0)
return fractions.Fraction(*final_frac).denominator
def problem_34():
fact_dict = {}
for i in xrange(10):
fact_dict[i] = math.factorial(i)
num_sum = 0
for i in xrange(3, fact_dict[9]*6): #6*9! < 999999 need MUCH better upper bound, but this works
if sum(fact_dict[int(x)] for x in str(i)) == i:
num_sum += i
return num_sum
def problem_35():
def rotate_num(n):
if n < 10:
return n
chars = [c for c in str(n)]
chars.insert(0, chars.pop())
return int(reduce(operator.add, chars))
primes = set(utils.get_primes_below(1000000))
count = 0
for p in primes:
worked = True
for i in xrange(len(str(p))):
p = rotate_num(p)
if not p in primes:
worked = False
break
if worked:
count += 1
return count
def problem_36():
num_sum = 0
for i in xrange(1000000):
if utils.is_palindrome("{0}".format(i)) and utils.is_palindrome("{0:b}".format(i)):
num_sum += i
return num_sum
def problem_37():
def is_truncatable_both_directions(prime, primes):
str_prime = str(prime)
for i in xrange(len(str_prime)):
if not (int(str_prime[i:]) in primes and int(str_prime[:i+1]) in primes):
return False
return True
primes = set(utils.get_primes_below(1000000))
results = [prime for prime in primes if is_truncatable_both_directions(prime, primes)]
return sum(results[4:])
def problem_38():
base = 1
multipliers = range(1,10)
possibilities = []
finished = False
while not finished:
# for j in xrange(2):
for i in xrange(2,10):
parts = [str(base * m) for m in multipliers[:i]]
num = reduce(operator.add, parts)
if len(num) > 9:
if i == 2:
finished = True
continue
if utils.is_pandigital(num):
possibilities.append(int(num))
base += 1
return max(possibilities)
def problem_39():
count = collections.Counter()
quit_count = 0
triplets = utils.pythagorean_triplets(return_r = True)
r = 0
while r < 1000: #excessive but this is fast enough
triplet = triplets.next()
r = triplet[-1]
triplet = triplet[:3]
s = sum(triplet)
if s < 1000:
count.update([s])
else:
quit_count += 1
return max(count.iteritems(), key = operator.itemgetter(1))[0]
#it hurts to brute force this when it could be done so much smarter, but I have to catch up :)
def problem_40():
huge_number = ''
i = 1
while len(huge_number) < 1000000:
huge_number += str(i)
i += 1
return reduce(operator.mul, (int(huge_number[10**x - 1]) for x in xrange(6)))
# def problem_40(): #Doesn't work but would be so fast
# def get_index_values(indices):
# max_index = max(indices)
# lengths = [0, 9]
# length = 1
# max_calculated = 9
# while max_calculated < max_index:
# length += 1
# max_calculated += 9*10**(length-1)*length
# lengths.append(max_calculated)
# print lengths
# lengths = np.array(lengths)
# results = []
# for i in indices:
# if i == 0: #HACK
# results.append(1)
# continue
# length = np.searchsorted(lengths, i)
# num_indx = (i - lengths[length - 1]) //length
# num = lengths[length - 1] + num_indx + 1
# dig_indx = (i - lengths[length - 1])%length
# print i, length, num, num_indx, dig_indx, lengths
# results.append(int(str(num)[dig_indx]))
# return results
# one_indexed_values = np.array([1, 10, 100, 1000, 10000, 100000])
# # one_indexed_values = np.array([1, 10, 100, 1000])
# return get_index_values(one_indexed_values - 1)
# def problem_41():
# primes = utils.get_primes_below(1000000000)
# for prime in primes:
def problem_41():
for length in xrange(9, 1, -1):
options = utils.pandigitals(length)
for num in options:
if utils.is_prime(num):
return num
def problem_42():
count = 0
with open('euler_resources/words.txt', 'rb') as f:
reader = csv.reader(f, delimiter=',')
words = [row for row in reader][0]
triangle_nums = utils.triangle_numbers()
triangle_set = set([triangle_nums.next() for i in xrange(2000)]) #arbitrarily big
for word in words:
score = sum([ord(x.upper()) - 64 for x in word])
if score in triangle_set:
count += 1
return count
def problem_43():
def condition(num):
snum = str(num)
return (int(snum[1:4]) % 2 == 0 and \
int(snum[2:5]) % 3 == 0 and \
int(snum[3:6]) % 5 == 0 and \
int(snum[4:7]) % 7 == 0 and \
int(snum[5:8]) % 11 == 0 and \
int(snum[6:9]) % 13 == 0 and \
int(snum[7:10]) % 17 == 0)
num_sum = 0
for pandigital in utils.pandigitals(length = 9, include_0 = True):
if condition(pandigital):
num_sum += pandigital
return num_sum
def problem_44(): #TOO slow
starting_size = 10000
pentags = utils.pentagonals()
p = [pentags.next() for i in xrange(starting_size)]
p_set = set(p)
combs = itertools.combinations(p, 2)
diffs = []
for c in combs:
if c[0] + c[1] > p[-1]:
if utils.is_pentagonal(c[0] + c[1]) and utils.is_pentagonal(abs(c[1] - c[0])):
diffs.append(abs(c[0]-c[1]))
else:
if (c[0] + c[1]) in p_set and abs(c[1] - c[0]) in p_set:
diffs.append(abs(c[0] - c[1]))
return diffs
def problem_45():
tris = utils.triangulars()
desired_index = 2
current_index = 0
for num in tris:
if utils.is_hexagonal(num) and utils.is_pentagonal(num):
if current_index == desired_index:
return num
current_index += 1
def problem_46():
# try brute forcing it
primesl = utils.get_primes_below(10000)
primess = set(primesl)
num_primes = len(primesl)
for current_num in xrange(9, primesl[-1], 2):
if current_num in primess:
continue
found_solution = False
for prime in primesl:
if prime > current_num:
break
res = np.sqrt((current_num - prime)/2)
if res == int(res):
found_solution = True
break
if not found_solution:
return current_num
def problem_47():
set_list = []
set_list_len = 4
current_num = 5 #kind of arbitrary
while(True):
c = collections.Counter(utils.prime_factorize(current_num))
new_set = set()
for key, value in c.iteritems():
new_set.add(key**value)
set_list.append(new_set)
if len(set_list) > set_list_len:
set_list.pop(0)
lengths = [len(s) == set_list_len for s in set_list]
if len(set.intersection(*set_list)) == 0 and all(lengths):
return set_list, current_num - set_list_len + 1
current_num += 1
def problem_48():
num_sum = 0
for i in xrange(1, 1001):
num_sum += i**i
return int(str(num_sum)[-10:])
def problem_49():
primes = np.array(utils.get_primes_below(10000))
primes = primes[primes > 999]
primes_set = set(primes)
sets_of_3 = []
for i, primei in enumerate(primes[:-4]):
for j, primej in enumerate(primes[i + 1:]):
step = primej - primei
if (primej + step) in primes_set:
sets_of_3.append((primei, primej, primej + step))
answers = []
for s in sets_of_3:
sets = [set(str(x)) for x in s]
if all(e == sets[0] for e in sets):
answers.append(s)