def fits(a, b): return is_prime(cat(a, b)) and is_prime(cat(b, a)) # Build a tree. # 1 + 2 - 3 # | # + - 3 # # 2 - 3 # # 3 primes = sorted(gen_primes(10**7))
def go():
checked = set()
for prime in primes(10 ** 6):
prime_str = str(prime)
for prime_char in set(prime_str):
wild_str = prime_str.replace(prime_char, '*')
if wild_str in checked: continue
checked.add(wild_str)
# Replace each wildcard with a digit.
matches = []
for new_digit in range(10):
new_str = wild_str.replace('*', str(new_digit))
if new_str[0] == '0': continue
if is_prime(int(new_str)):
matches.append(int(new_str))
if len(matches) == 8:
return matches