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Google treasure hunt: last puzzle

Few days back google announced about last leg of google treasure hunt journey. This time they provided unix epoch time 1212448500, time when puzzle was supposed to get released.
You can use http://www.epochconverter.com/ to convert it to human readable format. This side also provides list of available methods to get epoch time, convert it to human readable format and vice-versa.

PHP date(output format, epoch); Output format example: ‘r’ = RFC 2822 date
Python import time first, then time.gmtime(epoch)
MySQL from_unixtime(epoch, optional output format)

So the puzzle was supposed to release at
Mon, 02 Jun 2008 23:15:00 GMT, for India: Tuesday, June 03, 2008 4:45:00 AM (middle of the night).

Forth Puzzle is available here. Its a bit tricky, but i wrote a c program to calculate the number using brute force method…and it worked.(Share how you did it or is there some shortcut which works without any programming). Problem is to find a prime number which in turn can be expressed as sum of of n consecutive prime numbers. Your answer should satisfy 4 such list of prime numbers of given length.

So its over for now and soon they are going to contest winners and rewards. Hope i could have been one :) . But I have submitted this puzzle after long delay.(Was sleeping when it was released)

June 4, 2008 | Filed Under programming 
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Comments

4 Responses to “Google treasure hunt: last puzzle”

  1. Bryce on June 5th, 2008 5:09 am

    This one was pretty fun. I couldn’t find a good mathematical approach (Problems related to sums of primes seem to be hard. See the Goldbach conjecture), so I wrote a Haskell program that used a tower of lazy immutable Arrays, each built by referencing an arrays of shorter consecutive prime sums. I then marched linearly through the array for the longest consecutive sum, until I found a prime and then used a binary search to check if that number was found in each of the other arrays. Since each of the arrays can be defined in terms of each other, this solution represents a sort of dynamic programming solution, and since Haskell is lazy the binary search doesn’t have to compute the entire array that we’re performing binary search on. It still took about 9 seconds to find the answer on my laptop though. I’m interested to see more elegant solutions.

  2. Abhishek Ojha on June 5th, 2008 7:00 am

    good Luck !

  3. Puzzle puzzle every where : Burad’s Blog on June 7th, 2008 7:33 pm

    […] « Google treasure hunt: last puzzle […]

  4. Ya, I Am A Dastard on June 24th, 2008 8:57 am

    when brute works, nothing can be better :)

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