Can you solve it? The Greplin programming challenge

Post by leif » Sat, Oct 09, 2010, 5:43 AM UTC

dasil003 wrote: post #126

leif wrote: post #118

Earlier quoted context omitted.

I can't read ruby, but here's something a little smarter than brute force in C (on its way to DP, but I couldn't be arsed to work out the recurrence so I just iterated until it stabilized): http://gist.github.com/617854

It looks similar to mine, but you got lucky (or unlucky depending on how you look at it) that the longest palindrome had an odd character count. The confusing bits in the Ruby are actually just the definition of an even and odd palindrome finder, which are the same except for two seed values for where the first comparison is conducted and it's length.

Post by Tichy » Sat, Oct 09, 2010, 7:49 AM UTC

lisper wrote: post #85

Too easy to solve by brute force. I'd suggest looking at Project Euler for inspiration.

Post by zmitri » Sat, Oct 09, 2010, 8:52 AM UTC

tbrownaw wrote: post #110

zmitri wrote: post #24

The last question isn't that difficult if you brute force it and have loads of memory. I tried to do it in python using itertools on my work thinclient and got a memoryerror. If you however break up your combinations.. you're good to go! Fun, made my day. Good idea greplin dudes!

Not sure what you'd need the loads of memory for? int[] nums = {...} for i = 1 to (2^length(nums) - 1) int[] possibility = { nums[x] where (2^x bitand i) > 0 } test possibility and perhaps increment hit counter

Post by manveru » Sat, Oct 09, 2010, 10:36 AM UTC

dantle wrote: post #123

staunch wrote: post #100

Earlier quoted context omitted.

Easy job for a regex: while ($string =~ /((\w+)\w?(??{reverse $2}))/g) { print "$1\n"; }

fuckin nice. now I feel like a doofus for using ruby, when I thought it was straightforward.

    text.scan(/(.)(.)(.)(.)(\3)(\2)(\1)/)

Post by aristidb » Sat, Oct 09, 2010, 12:42 PM UTC

1amzave wrote: post #23

So what languages did everyone use? I decided to try a different one on each level, so I used Python, bash (letting GNU coreutils 'factor' do the hard work), and Haskell, respectively.