I did that, but it's still taking too long because of how large the numbers are. I've been stuck with this all day.

You could try storing primes in a global/static variable. That way you only calculate them once during the first function call.

I know this feeling! I've been recently learning haskell and when i see other people's solution i'm like wow!, i'm still super bad at this. haha

Can somebody give me a hint for a python solution? I have optimized the prime number searching function using sieve of Eratosthenes algorithm but the main function is taking very long time.

I am stuck with python. I have used very fast method for searching prime_numbers, but still timeout. Don't know where I am messing up.

This solution is actually fast. I ran double(30, 20000) for the above solution and my solution without the "if b > 0.00000000001" part. my solution took 565ms wheras above solution took 165ms.same code but way faster.

This was one hell of a good kata. Spend whole day and just got it done with python. Now watching other people's solution and I just realised I know nothing. People are just way smarter. Bookmarking this. Will come back later and practice other people's solution.

Damn! you and I followed exactly the same way. i have wrote the exact same for loop and thus excution time ran out but after someday I wrote the following code and it worked.