Dijkstra, first look

Initially the program is a little daunting, but I think I have a clear grasp on what Dijkstra's Algorithm is supposed to be doing....it will just be another story to convert it into code.

I decided that the best data structure I can think of to simply implement for this assignment is an array of arrays, or in this case a list of lists. I chose to make my own type of data container/node to hold all the information that was required for the grid. I found this a little easier since I'm not entirely familiar with the interface of the provided data structures. I was initially confused as to what some of these functions were for, especially in regards to the costFrom() function. But after talking to Dr. Wallace, it turns out that most of the hard work is done for us, this is simply a getter method for printing. I was also confused at first as to what the coordinates of the destination point were, I didn't find it very clear that the first argument of the destinations was the clear and definite choice. (Thanks Soren!)

I spent a fair bit of time exploring the methods provided for retrieving specific attributes from the GridCoordinate object and how I could use those to complete this assignment. I have to say, my Java skills have jumped quite a bit since I started this assignment, I really had to learn a lot to understand how each object knew how to access what. Our class has had very little Java experience, so all of this helps a great deal.

The custom container will store d, pi and a reference to the node it represents. This will make all my information readily available.

To create the grid, I need to know the size of the world we're dealing with. The only way I know of, and it's a hideous one...is to just iterate through the entire list of nodes and take the largest value of both x and y to determine the size. It is terribly inefficient but it does work for the time being until I find a more efficent method.

I decided to create my list of unvisited nodes at the same time as creating the grid to increase efficiency and reduce the chance of a bug implementing it later on another way.

http://renaud.waldura.com/doc/java/dijkstra/ Is a nifty little website I found with a nice rundown of the algorithm with a few examples, ones that I'm sure I'll be using to debug this beast when I get to it.