First of all we only check numbers below or equal to 20! because we know for sure that this number will satisfy the criterium of the question, we just don’t know if there is a result below this number, we also know that the number must be at least 20. For this reason we check all numbers between 20 and 20! if all numbers between 1 and 20 is a divisor – if one of the numbers fail, we move on to the next candidate. As soon as a candidate proves to be correct, we exit and return the result.

As the previous three problems I have posted about, this is written to run on node.js.

Installing gitosis
Even though I use github privately, I opted for the selfhosted version for our work-repositories. The reasoning behind this was mostly that we host our own subversion repo’s today, then we could just as well host our own git repo’s. (This also made the change possible without needing the company to pay more for hosting than we allready do).

I will not go through the installation, but just link to this excellent guide I followed to get everything up and running.

Creating repositories
When all users, roles and repositories have been saved in the file gitosis.conf – you are able to create local repositories for your projects and push the to the server. (This works just as with github, btw). Again instead of showing you an example I recommend the guide I used.

Exporting from subversion
The easiest part was exporting from subversion and commiting in git. Only downside was that the repository history was lost. But I still have the subversion repos as a backup, if I need them in the future.

Final thoughts
We are running Redmine and Hudson on our dev-server. Both were setup to use the git repository instead of the svn repo in just under 30 minutes. (And that included 5 projects). Apart from some splitting up of projects into minor parts this was pretty straightforward.

This time I have decided to explain the code a bit more, through comments – since this problem is a bit more tricky than the previous two problems.

Once again, you will need node.js to run the code.

The problem is “Find the sum of all the even-valued terms in the [fibonacci] sequence which do not exceed four million.”

My take on the solution was to run through all fibonacci numbers below 4.000.000 and adding them to the total, if they were equal. The next fibonacci number is calculated by always saving the last two numbers found.

You will need node.js to run this code.

The first problem on the list is very simple. “Find the sum of all the multiples of 3 or 5 below 1000″. The solution, then, must be to find all numbers that are multiples of 3 and 5, and then adding those…

This solution is pretty simple. You (probably) need nodejs to run the code.

One of the books which are still in my wishlist is “Patterns of Enterprise Application Architecture”. It is a phenomenal book, or rather catalog, of design patterns specifically for enterprise software, but most of them are universally usable. I first heard about this book when the FLOW3 project started, and now having read the book I find it easier to understand some of the architectural decisions made by the FLOW3 team. Furthermore the FLOW3 framework made it a lot easier to understand a lot of the patterns from the book. since many of them has a implementation in the framework.

The author, Martin Fowler, has published a short overview of each of the patterns at http://www.martinfowler.com/eaaCatalog/.

It is hard to go into detail about the book, since it would involve discussing a lot of the patterns – but I would just recommend it for any developer, you will learn something!

The two scripts are almost identical. Actually the only difference is the action the shell script should call (add or remove). The rest of the scripts are completely the same.

I call this file addhost.

using terms from application "Quicksilver"
	on process text txt
		set the_password to "YOURPASSWORD"
		repeat with delimiter_position from 1 to (length of txt)
			if character delimiter_position of txt = " " then exit repeat
		end repeat
		if delimiter_position = (length of txt) then
			set hostname to txt as string
			set ipaddress to ""
		else
			set hostname to characters 1 thru (delimiter_position - 1) of txt as string
			set ipaddress to characters (delimiter_position + 1) thru (length of txt) of txt as string

		end if

		do shell script "sudo hosts.sh add " & hostname & " " & ipaddress password the_password with administrator privileges

		return nothing
	end process text
end using terms from

I call this file removehost.

using terms from application "Quicksilver"
	on process text txt
		set the_password to "YOURPASSWORD"
		repeat with delimiter_position from 1 to (length of txt)
			if character delimiter_position of txt = " " then exit repeat
		end repeat
		if delimiter_position = (length of txt) then
			set hostname to txt as string
			set ipaddress to ""
		else
			set hostname to characters 1 thru (delimiter_position - 1) of txt as string
			set ipaddress to characters (delimiter_position + 1) thru (length of txt) of txt as string

		end if

		do shell script "sudo hosts.sh remove " & hostname & " " & ipaddress password the_password with administrator privileges

		return nothing
	end process text
end using terms from

Now I am able to create a local domain by opening Quicksilver (double-control in my case) press period, write the domain name, press tab, and select the addhost action (ad is enough in my case). Removing is just as easy – the last step is just to select the removehost action (re is enough in my case).

#! /bin/bash
DEFAULT_IP=127.0.0.1
IP=${3:-$DEFAULT_IP}

case "$1" in
  add)
        echo "$IP $2"  >> /etc/hosts
        ;;
  remove)
        sed -ie "\|^$IP $2\$|d" /etc/hosts
        ;;

  *)
        echo "Usage: "
		echo "hosts.sh [add|remove] [hostname] [ip]"
		echo
		echo "Ip defaults to 127.0.0.1"
		echo "Examples:"
		echo "hosts.sh add testing.com"
		echo "hosts.sh remove testing.com 192.168.1.1"
        exit 1
        ;;
esac

exit 0

As you can see the script defaults the ip to 127.0.0.1 for easy creation of local domains. Next step is to create a quicksilver (and a gnome do) plugin for easy creation without ever touching the terminal. (Even though we all love the terminal, right?)

I had an import script for importing demo files (in mp3 format) to a database used at Voicearchive. Only problem the import script depended on the files being named precisely according to a specific rule. But for some reason some times it was named with uppercase letters, and sometimes with lowercase letters. I decided to rename all files to lowercase, and change the importscript accordingly.

find . -maxdepth 1 -type f -execdir rename 'y/A-Z/a-z/' '{}' \;