Week 5 Day 3: Lost in the Maze

Major Activities Activity of the Day:  We started the day with an assignment to write a MazeSolver class that takes in a string representing a maze and implements a breadth-first search (BFS) to find the best solution.  This was rather frustrating for me at first, since I'm used to depth-first searches (DFS), and I find the BFS algorithm to be simply unintuitive.  However, after a lot of work, I figured out how to make it happen, and it was awesome!  But why use it?  Simple - BFS is always guaranteed to find a path of the shortest possible length between two points!  That's why navigation technologies use it; DFS might take you down the block through several continents, but BFS will get you there ASAP, because it's finding the shortest possible route.

So it turned out that, though we were supposed to finish at 11, almost everyone was still working on it through lunch.  We kept at it for a bit, and then Avi took those who wanted to watch him implement a solution and ran through it.  Others kept plugging away.

At the end of all this, it was 4PM, and the day was nearly over.

OK, OK, I know you want to hear about how I did.  I finished at noon, and then spent the next few hours refactoring and making things prettier, OK?  Sorry, didn't want to brag, but you forced me to.

Actually, I had a lot of fun with it - instead of defining arrays with 3 elements (x-coordinate, y-coordinate, reference to another point), I created a Node class based on a Struct with elements x, y, and reference.

Huh? you ask.  What's a Struct?  Well, I'm glad you asked.  We did blogs in the late afternoon, and today I presented.  You can see my post at http://amcaplan.wordpress.com/2014/03/05/struct-rubys-quickie-class/.  Structs are awesome little class factories that create simple data storage classes and give you lots of extra methods to go with.

In lecture, we discussed the creation of a nested params hash in Sinatra to create objects from forms in a more organized way.  A properly constructed params hash makes construction of objects really simple.  Let's say I have a Person object with name, height, and weight attributes.  I could do this:

person = Person.new
person.name = params[:name]
person.height = params[:height]
person.weight = params[:weight]
person.save

But I can also do it more simply if I have everything nested inside params[:person]:

person = Person.create(params[:person])

Isn't that much nicer?

We were already overloaded with homework from yesterday, but we got some more today anyway, for whenever we finish that.  I just did as much as I could from yesterday's homework.

Skills developed: Breadth-first search, use of nested params for forms in Sinatra