Project Euler #41

euler41.py

from itertools import chain
from math import sqrt

def comb(l):
    if len(l) == 0:
        yield []
    else:
        for i in range(len(l)):
            for cc in comb(l[:i] + l[i + 1:]):
                yield [l[i]] + cc
def combn(n):
    l = [c for c in str(n)]
    return [int(''.join(x)) for x in comb(l)]

def isprime(n):
    for x in range(2, int(sqrt(n)) + 1):
        if n % x == 0:
            return 0
    return 1

print max(x for x in
            (chain(*[combn(int('123456789'[:i]))
                for i in range(1, 8)])) if isprime(x))