Project Euler solutions

LIESMICH.md

I moved my solutions to a full-fledged repo, so that's where you should go looking for my latest kludges.

Problem_1.py

# http://projecteuler.net/problem=1
sum(filter(lambda n: False if n % 3 and n % 5 else True, range(0,1000)))

Problem_10.py

#https://projecteuler.net/problem=10
is_prime = lambda n: not len(filter(lambda x: not n % x, range(2,int(round(sqrt(n)))+1)))

sum(filter(is_prime, xrange(2,2000000))) # slow; use gist.github.com/jboynyc/6247226 instead

Problem_2.py

# http://projecteuler.net/problem=2
def fibb(max=4000000, l=[1,2]):
    n = l[-1] + l[-2]
    if n < max:
        l.append(n)
        fibb(max,l)
    else:
        return l

sum(filter(lambda x: False if x % 2 else True, fibb()))

Problem_3.py

# http://projecteuler.net/problem=3
def factors_of(n):
    return filter(lambda x: not n % x, range(1,int(n**.5)))

is_prime = lambda n: not len(filter(lambda x: not n % x, range(2,int(round(sqrt(n)))+1)))

max(filter(is_prime, factors_of(600851475143))) 

Problem_4.py

# http://projecteuler.net/problem=4
def is_palindrome(n):
    if str(n)[0] == str(n)[-1] and str(n)[1] == str(n)[-2] and str(n)[2] == str(n)[-3]:
        return True
    else: 
        return False

l = []
for i in range(100,1000):
    for j in range(100,1000):
        l.append(i*j)

max(filter(is_palindrome, l))

Problem_6.py

# https://projecteuler.net/problem=6

sum(range(1,101))**2 - sum(map(lambda n: n**2, range(1,101)))

Problem_7.py

# https://projecteuler.net/problem=7

is_prime = lambda n: not len(filter(lambda x: not n % x, range(2,int(round(sqrt(n)))+1)))

def nth_prime(n, c=1, p=2):
    if c==n: 
        return p
    else:
        if is_prime(p+1): return nth_prime(n, c+1, p+1)
        else: return nth_prime(n, c, p+1)
    
nth_prime(10001) # exceeds maximum recursion depth; use gist.github.com/jboynyc/6232278 instead

Problem_8.py

# https://projecteuler.net/problem=8
def qp(i):
    from operator import mul
    return reduce(mul, map(int, list(i)))

s = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450"
l = []
for i in range(0,len(s)-4): l.append(s[i:i+5])

p = map(qp, l)
l[p.index(max(p))]

Problem_9.py

# https://projecteuler.net/problem=9
def is_py_trip((a, b, c)):
    return True if (a*a + b*b == c*c) and (a < b < c) else False

import itertools
from operator import mul
r = filter(lambda t: True if sum(t)==1000 and is_py_trip(t) else False, itertools.combinations(xrange(1,998),3))
reduce(mul,r[0])