def circular_primes(maximum):
# Immediately Filter out all prime numbers greater than 2 that contain an
# even digit, since at least one of their rotations won't be prime
primes = filter(lambda p: p == 2 or non_even(p),
takewhile(lambda p: p < maximum, common.primes()))
return [p for p in primes if all(n in primes for n in rotations(p))]
def sum_of_primes_below(n: int) -> int:
"""
Returns the sum of all of the prime integers that are less than n.
>>> sum_of_primes_below(10)
17
"""
return sum(itertools.takewhile(lambda x: x < n, primes()))
def concise_factors(factors):
result = []
for p in common.primes():
assert p <= factors[0]
result.append(0)
while factors and factors[0] == p:
result[-1] += 1
factors.pop(0)
if not factors: return tuple(result)
def nth_prime(n: int) -> int:
"""
Returns the nth prime integer.
>>> nth_prime(1)
2
>>> nth_prime(6)
13
"""
return next(itertools.islice(primes(), n - 1, None))
def factorize(n):
factors = []
if n > 1:
for p in common.primes():
while n % p == 0:
factors.append(p)
n = n / p
if n == 1:
break
return factors
def solution():
# Note: same method as problem 108
threshold = 4*10**6
# Get the maximum number of primes that would be required to find the least
# value of `n` (using the same reasoning as that of the distinct()
# function)
factors = list(islice(primes(), 0, log(threshold, 2) + 1))
# Order the prime factors, and add terms with multiplicities greater than
# 1 that are smaller than the largest retrieved prime
factors = sorted([(p**i, p, i)
for p in factors
for i in takewhile(lambda n: p**n <= max(factors),
count(1))])
# Prime factorization mapping for potential results, producing strictly
# increasing values (before minimization)
least = {}
results = []
for idx, (_, p, i) in enumerate(factors):
# Increase the multiplicity of p
least[p] = i
if distinct(least) > threshold:
# Make a new copy of the factorization dictionary before the
# minimization process
result = dict(least.items())
# Keep track of prime factors whose multiplicity has been finalized
checked = set()
for _, prime, _ in reversed(factors[:idx]):
if prime in checked:
continue
# Attempt reducing the multiplicity of `prime`...
result[prime] -= 1
# ... and backtrack if necessary
if distinct(result) <= threshold:
result[prime] += 1
# Finalize `prime`'s multiplicity
checked.add(prime)
results.append(product(b**e for b, e in result.items()))
return min(results)
def solution():
pgroups = {}
for p in takewhile(lambda p: p < 10000,
dropwhile(lambda p: p < 1000, primes())):
pgroups.setdefault(''.join(sorted(str(p))), []).append(p)
for plist in pgroups.values():
if len(plist) >= 3:
for pcombo in combinations(plist, 3):
a, b, c = pcombo
if a - b == b - c:
return ''.join(map(str, pcombo))
def solution():
iprimes = primes()
for n in count(5):
pgroups = {}
# Check all n-digit primes
for p in takewhile(lambda p: p < 10**n,
dropwhile(lambda p: p < 10**(n-1), iprimes)):
for k in keys(p):
pgroups.setdefault(k, []).append(p)
for key, plist in sorted(pgroups.items()):
if len(plist) == 8:
return (key, min(plist))[1]
def admissible(limit):
def partial(n, maxfactor, ps):
if n >= limit:
return
yield n
ps0, ps1 = tee(ps)
res0 = partial(n*maxfactor, maxfactor, ps0)
nextp = next(ps1)
res1 = partial(n*nextp, nextp, ps1)
for a in coalesce(res0, res1):
yield a
ps = primes()
first = next(ps)
return partial(first, first, ps)
def solution():
base = 1000
# Keep the same iterator throughout to pull more prime values whenever
# necessary
iprimes = primes()
# Use a set for quick prime lookups
pset = set()
for i in count():
limit = base*(10**i)
pset.update(takewhile(lambda p: p < limit, iprimes))
tuples = set((p,) for p in pset)
for j in range(2, 6):
new_tuples = set()
for ts in combinations(tuples, 2):
t = tuple(sorted(set([e for t in ts for e in t])))
if len(t) != j:
continue
for a, b in permutations(t, 2):
n = int(str(a) + str(b))
if n < limit:
if n not in pset:
break
elif not is_prime(n):
break
else:
new_tuples.add(t)
tuples = new_tuples
if tuples:
return min((sum(t), t) for t in tuples)
def solution():
# Initial number of primes to fetch
fetch = 1000
# Keep the same iterator throughout to pull more prime values whenever
# necessary
iprimes = primes()
# Use a set for quick prime lookups
pset = set()
# Skip the given examples
start = 647
# Number of consecutive numbers to have 4 distinct prime factors
consecutive4 = 0
while True:
pset.update(islice(iprimes, 0, fetch))
stop = max(pset) + 1
for n in range(start, stop):
if n not in pset:
if len([1 for d in divisors(n) if d in pset]) == 4:
consecutive4 += 1
if consecutive4 == 4:
return n - 3
continue
consecutive4 = 0
start = stop
# Triple the number of available primes
fetch *= 2
def solution():
pset = set(takewhile(lambda p: p < 1e6, primes()))
# Minimum number of consecutive primes summing to a prime < 1e6, using the
# provided examples
minc = 21
# Plausible upper bound on the primes that will be part of the sum
max_prime = 10**6 / (minc - 1)
psubset = sorted([p for p in pset if p < max_prime])
# Using the smallest (first) primes, compute an upper bound on the number
# of consecutive primes that can sum up to < 1e6
maxc, _ = deque(takewhile(lambda t: t[1] < 1e6,
((i, sum(psubset[:i]))
for i in range(1, len(psubset) + 1))),
maxlen=1).pop()
for length in range(maxc, minc, -1):
for i in range(len(psubset) - length):
s = sum(psubset[i:i+length])
if s in pset:
return s
def solution():
return sum(takewhile(lambda n: n < 2e6, common.primes()))
# 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? from common import primes, take print(list(take(10001, primes()))[-1])
(i) each of the three terms are prime, and,
(ii) each of the 4-digit numbers are permutations of one another.
There are no arithmetic sequences made up of three 1-, 2-, or 3-digit primes,
exhibiting this property, but there is one other 4-digit increasing sequence.
What 12-digit number do you form by concatenating the three terms in this
sequence?
'''
import common
import itertools
useful_primes = set(
p for p in itertools.takewhile(lambda x: x < 10**4,
itertools.dropwhile(lambda x: x < 10**3,
common.primes())))
def euler049():
for i in useful_primes:
if i == 1487: continue # skip known solution
for j in useful_primes:
if i >= j: continue
if sorted(str(i)) != sorted(str(j)): continue
k = j + (j - i)
if k not in useful_primes: continue
if sorted(str(i)) != sorted(str(k)): continue
return int('%d%d%d' % (i,j,k))
common.submit(euler049(), expected=296962999629)
from common import primes print sum(primes(2000000))
def sum_primes_below(n):
return sum(itertools.takewhile(lambda x: x < n, common.primes()))
(i) each of the three terms are prime, and,
(ii) each of the 4-digit numbers are permutations of one another.
There are no arithmetic sequences made up of three 1-, 2-, or 3-digit primes,
exhibiting this property, but there is one other 4-digit increasing sequence.
What 12-digit number do you form by concatenating the three terms in this
sequence?
'''
import common
import itertools
useful_primes = set(p for p in itertools.takewhile(
lambda x: x < 10**4,
itertools.dropwhile(lambda x: x < 10**3, common.primes())))
def euler049():
for i in useful_primes:
if i == 1487: continue # skip known solution
for j in useful_primes:
if i >= j: continue
if sorted(str(i)) != sorted(str(j)): continue
k = j + (j - i)
if k not in useful_primes: continue
if sorted(str(i)) != sorted(str(k)): continue
return int('%d%d%d' % (i, j, k))
common.submit(euler049(), expected=296962999629)
#!/usr/bin/env python
from common import is_prime, primes
MAX = 1000000
pnums = set(primes(MAX))
def rotations(num):
s = str(num)
return [int(s[i:] + s[:i]) for i in range(len(s))]
def is_cicrular(num):
return all([a in pnums for a in rotations(num)])
circulars = len(list(filter(is_cicrular, pnums)))
print(circulars)
i = 3
while i < n:
if not is_prime(i):
yield i
i += 2
def squares(n=10000000):
""" Find squares below n """
i = 1
while True:
sq = i**2
if sq > n:
break
yield sq
i += 1
for oc in odd_composites():
for p in primes(oc - 1):
diff = oc - p
sq = list(squares((diff) // 2))
if (diff // 2) in sq:
break
else:
print("not found when odd is {}".format(oc))
break
def value(n): # assert isinstance(n, tuple) return common.product(p**c for p,c in zip(common.primes(), n))
def candidate_bs():
"""
Returns all possible values for the coefficient b, using the fact that b
must be prime for there to be a consecutive sequence of generated primes
"""
return takewhile(lambda p: p < MAX_MODULUS, common.primes())
def solution():
return next(islice(primes(), 10000, None))
def sum_primes_below(n):
return sum(itertools.takewhile(lambda x: x < n,
common.primes()))
#!/usr/bin/env python from itertools import count from common import primes MAX = 2000000 s = sum(a for a in primes(MAX)) print(s)
#!/usr/bin/env python
from common import primes
MAX = 1000000
pnums = set(p for p in primes(MAX))
def get_combinations(n):
o = set()
s = str(n)
for a in range(len(s) - 1):
o.add(int(s[a + 1:]))
o.add(int(s[:a + 1]))
return (o)
def are_combs_prime(n):
return all([a in pnums for a in get_combinations(n)])
truncatable_primes = filter(are_combs_prime, (p for p in pnums if p > 9))
print(sum(truncatable_primes))
# set of divisors # start with 2520, count up # or, start with 2520 and multiply by all the remaining divisors? # 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 # list of odd numbers, also 2? from common import primes full_set = range(1, 21) test = [] temp= [] divisors = [] answer = 1 for x in full_set: test = primes(x) temp = divisors[:] for y in test: if y in temp: temp.remove(y) else: divisors.append(y) print x, divisors for x in divisors: answer *= x print answer # def check_divisors(number): # divisors = xrange(1, 11)