 From: lisa 20040716 11:58 am (UTC)
 (Link)

i know you just asked evan for the answer
 From: brad 20040716 12:05 pm (UTC)
 (Link)

Nuhuh. I gots the ugly Perl to prove it!
what was the problem? did you see a picture of their billboard? that's a fun problem too.
 From: brad 20040716 02:13 pm (UTC)
 (Link)

Just solved the billboard: "Congratulations. You've made it to level 2. Go to XXXXXXXXXX.org and enter XXXXXXXXXXXXX as the login and the answer to this equation as the password.
f(1)= xxxxxx f(2)= xxxxxx f(3)= xxxxxx f(4)= xxxxxx f(5)= __________"
thats been solved too, and ironically the answer can be found with google :D
 From: brad 20040716 02:37 pm (UTC)
 (Link)

Just posted the answer below, well with the answer xxxxx'ed out.
That's annoying people posted it on google. Kinda kills the point. (Deleted comment)
From: (Anonymous) 20040716 05:04 pm (UTC)
 (Link)

Are you aware that you just posted the solution to part 1? ;)
(Posted anonymously so it'll be screened)
 From: brad 20040717 05:00 pm (UTC)
 (Link)

Whoops. Thanks! Now blotted out: Part 2:
bradfitz@bini:~/proj/googleprime$ ./part2.pl  head 10
0 1 2 1: 718xxxxxxx
4 5 6 2: 8182845904
22 23 24 3: 8747135266
98 99 100 4: 7427466391
126 127 128 5: xxxxxxxxxx
 From: mart 20040716 02:50 pm (UTC)
 (Link)

Just out of interest (although the answers are all over the web) I decided to see how hard it would be to bruteforce this. My dumb script just tries all possible sets of ten after a bit of sanity checking, and then uses LWP to try the request with a short timeout. After 20 attempts it found it. It would have been less effective if people owned some of the other answers!
The second part is harder to brute force, but I imagine a few people still tried it anyway. I kinda wonder whether Google are more interested in people who were able to figure out the nature of the sequence or people who find creative ways (completely dumb brute force doesn't count) to solve the problem without figuring out the pattern separately first…
 From: brad 20040716 02:57 pm (UTC)
 (Link)

Hah. It was only at position 20? My script didn't output the position for round 1.
Nice problem solving, sir.
 From: mart 20040716 03:05 pm (UTC)
 (Link)

Not quite. I did some quick checks on the numbers before doing the requests. For example, if it starts with zero it is out (less than ten digits) and also a quick loop to test dividing between everything between 1 and some constant (I forget what it was now, and I've destroyed the program to solve the second problem!) to see if any of them give a whole number. Only then does it make the HTTP request.
I think it was somewhere above the 30th position although I can't remember exactly where it was and I'm too lazy to write the one line of code it'd take to find out, too.
 From: brad 20040716 03:34 pm (UTC)
 (Link)

Primes can only end in 1, 3, 7, or 9, so that helps filter it a bit, if you're doing some really slow HTTP check. :)
 From: mart 20040716 03:48 pm (UTC)
 (Link)

Aha… I knew there was some other prime rule I was forgetting. It's been a while since I did anything particularly mathematical. I should “practice” more.
I think they're also looking for people with the motivation to actually solve the problem. I bet most people (me included) just look at it and say, yeah that's trivial, but never really solve it.
 From: erik 20040716 01:05 pm (UTC)
 (Link)

Remember when we 0wn3d (or, rather, you 0wn3d) that floor word competition in Terry by writing some Perl? It was something about finding all of the words in the dictionary that have at least 3 pairs of letters, or how many other words could be formed from some word.
What was the nature of this question, anyway?
It must have been a pretty tricky puzzle if you had to use more than one line of Perl to solve it.
 From: brad 20040716 06:47 pm (UTC)
 (Link)

Thanks! 