doetheman / nodes-graph

Nodes-Graph

Please complete the following questions. For 1 and 2, please use Java. For 3, you can use any language you prefer. Compilable/runnable code is required, runnable code with tests that I can easily run to verify your submission is always preferred.

Please publish to Github and email me the link or create a .tar.gz file.

1. Imagine we have an interface "GNode" that looks like this:

   public interface GNode { public String getName(); public GNode[] getChildren(); }

   ** Observe that this GNode can be thought of as defining a graph. ** In implementing the functions below, you can assume that any graph defined by a GNode is acyclic (no cycles). ** Assume that when a GNode has no children, getChildren() returns a array of size 0, and not null. ** You can also assume that all children returned by getChildren() are not null.

   Implement a function with the following signature:

   public ArrayList walkGraph(GNode);
   

   which should return a ArrayList containing every GNode in the graph. Each node should appear in the ArrayList exactly once (i.e. no duplicates).

2. Implement a function with the following signature:

    public ArrayList paths(GNode node);
   

   which should return a ArrayList of ArrayLists, representing all possible paths through the graph starting at 'node'. The ArrayList returned can be thought of as a ArrayList of paths, where each path is represented as an ArrayList of GNodes.

   Example: Assume the following graph:

   A B E F C G H I D J

   paths(A) = ( (A B E) (A B F) (A C G) (A C H) (A C I) (A D J) )

3. Write a quick and dirty program (Shell, Python, Perl, Java, Lisp, C++, APL, or whatever) to produce a count of all the different "words" in a text file. Use any definition of word that makes logical sense or makes your job easy. The output might look like this:

   17 a 14 the 9 of 9 in 8 com 7 you 7 that 7 energy 6 to ...

   For this input file, the word "a" occured 17 times, "the" 14 times, etc.