C# - Generic Class To Create Node Tree From Array

Artem — Fri, 07 Aug 2020 00:19:54 +0000

Currently I find myself in the middle of a bunch of interview prep and am constantly running tests for Node Trees.

The Problem

If I test Breadth First Search (BFS), or Depth First Search (DFS), or reversing a Binary Search Tree (BST) I generally make a BST one line at a time...

IntNode root = new IntNode(1);
root.left = new IntNode(2);
root.right = new IntNode(3);
root.right.right = new IntNode(5);
root.right.left = new IntNode(4);

This method is painful and, seemingly, takes forever.
Especially when I just want to test a single algorithm.
Don't even get me started on doing multiple tests...

The Solution(?)

I wrote a neat little helper class to automate this process!

public abstract class Node<T, V> where T: struct where V: Node<T, V> { // in C# 8.0 you can use 'where T: notnull'
    public T val;
    public Node<T, V> left;
    public Node<T, V> right;

    protected Node(T val) {
        this.val = val;
    }

    public static V Instantiate(T val) {
        return (V)Activator.CreateInstance(typeof(V), val);
    }

    public static V FromArray(Nullable<T>[] array) {
        V GetFromArray(int index) {
            if(index >= array.Length || array[index] == null) return null;
            var node = Instantiate((T)array[index]);
            node.left = GetFromArray(index * 2 + 1);
            node.right = GetFromArray(index * 2 + 2);

            return node;
        }

        return GetFromArray(0);
    }

    public Nullable<T>[] ToArray() {
        Nullable<T>[] array = new Nullable<T>[10];

        int AddToArray(Node<T, V> node, int index) {
            if(index >= array.Length) Array.Resize(ref array, array.Length * 2);
            if(node is null) {
                array[index] = null;
                return -1;
            } else {
                int maxSize = index + 1;
                array[index] = node.val;
                maxSize = Math.Max(maxSize, AddToArray(node.left, index * 2 + 1));
                maxSize = Math.Max(maxSize, AddToArray(node.right, index * 2 + 2));

                return maxSize;
            }
        }

        int size = AddToArray(this, 0);
        Array.Resize(ref array, size);

        return array;
    }
}

All you do is have you class inherit from this base class and you can make as many Node Trees as you need!

public class IntNode: Node<int, IntNode> {
    public IntNode(int val): base(val) { }
}

Once you've made your class you can, simple, call the two (2) helper methods to either make a tree from an array or convert your tree to an array.

IntNode first = new IntNode(1);
first.left = new IntNode(2);
first.right = new IntNode(3);
first.right.left = new IntNode(4);
first.right.right = new IntNode(5);

IntNode second = IntNode.FromArray(new int?[]{ 0, 1, 2, 3, 4, 5, 6, 7 });

Console.WriteLine(String.Join(", ", first.ToArray())); // 1, 2, 3, , , 4, 5
Console.WriteLine(String.Join(", ", second.ToArray())); // 0, 1, 2, 3, 4, 5, 6, 7

Console.WriteLine(second.right.right.val); // 6
Console.WriteLine(IntNode.Instantiate(50).val); // 50

Hope this helps you with whatever Node Tree based activities you find yourself doing!

Using MVC With Unity

Artem — Sun, 21 Jun 2020 23:56:34 +0000

Quick warning- I tend to use framework and design pattern interchangeably.

Back in 2016 I remember seeing a lot of job openings seeking Unity developers with working knowledge of MVC framework. At the time it didn't make too much sense to me considering Unity primarily supports the Component framework. Thus I set out on a mission to create a project using the MVC framework exclusively.

TL;DR - it didn't end too well.
Here's what I learned along the way!

What actually is MVC?

MVC stands for Model-View-Controller.
Each of these are specific functionalities for working with data.
The model stores your data and manipulates it.
The view displays your data, generally you want to keep your view dumb (that is to day, it shouldn't store or manipulate any data).
The controller will fire off commands to your model to do stuff with your data.

Don't try to use one framework for your entire project

Much like how you'll often hear people telling you to not over use Singletons you shouldn't try to over use MVC. All frameworks have their specific functions and support specific features.

A good time to use MVC

I found that in instances of storing, manipulating, and displaying data (like keeping track of score, multiple choice answers, instructions, etc.) MVC is super useful.
I was able to decouple the logic behind multiple choice questions, which is super helpful when it's a last minute add from the UX team and nobody knows how it will look, or how the user will input the data, or what any of the questions or answers are.

A not so good time to use MVC

When you're trying to manipulate game elements like tiles in a match 3, or like 3D objects in a VR application, or storing state in your experience.
However, MVC is really good for manipulating chess or checker pieces on a game board.

Conclusion

MVC is a tool first and foremost, like all other frameworks and design patterns you should pick and choose which works best with what you are trying to do. If you find that using a specific style of coding is making your application harder to maintain, debug, and update then maybe consider not using it as much (or at all).

Are there any frameworks or design patterns you enjoy using?

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