prims | 3D Geometry Primitives for WebGL | Graphics library

I am trying to convert the following procedure from NetLogo 5 to 6.

NL5 Procedure:

I guess I have a simple problem, but I'm not able to solve it: I want to create a vector, call FFI on this vector and return it.

I have some questions about Prim`s algorithm.

Prim algorithms can find MST. In general implementation, It needs initialize all Nodes as INF. but i don`t know why this initialize needs.

Here is my implementation

I'm learning OpenGL following this video. While it's based on C++, I attempt to use Kotlin instead with lwjgl. As I code and run this:

I'm trying to implement Prim's Algorithm in my maze generator as described here. I've got it working as intended, but with an extra catch in my code of which I'm not sure why it's needed.

In my algorithm, I keep track of a list of cells that make up the maze in maze. I then look at the potential frontier cells (neighbouring cells to those that make up the maze), and pick one randomly. Let's call this the frontier. I then determine the neighbours of the frontier, and check which of the neighbours connect to the already existing maze. I connect the frontier node and the adjacent already in-maze node, remove the frontier node from the list of possible frontiers, add it to the maze, and finally add the newly found maze node's neighbours to the frontier list.

During this process, I make sure to only add nodes to the frontiers list that are not already contained in maze. (see the if (neighbour.Cell != null && !maze.Contains(neighbour.Cell)) statements.

However, my Algorithm seems to mess up if I don't end up double checking each chosenFrontier to see if they're not already contained in the maze. If I do not do this, the algorithm will end up thinking there's still frontier cells even in places where every adjacent tile is already part of the maze.

Why is this? Why do I need the if { ... } else { ...} statement there for my algorithm to succeed? I'm dumbstruck as to why it would be neccessary, since everywhere I add cells to my frontier lists, I already check whether they are already contained in maze. If they are, they aren't added to my frontier list. Yet somehow if I have to doublecheck my frontier list for cells that are already contained in the maze (and remove them). Where did I go wrong?

Here's my code:

I was trying to implement Prim's algorithm(eager) which requires to keep a track of best incoming edge(least cost) to a vertex. For this I use stl map as:

so I have this function next_vertex (which i will use as a helper functionf or prims algorithm later) which takes in two arrays, in_tree and distance and will return the vertex which is not part of the tree (has false value in in_tree) and has the shortest value in distance array.

I have tried writing the following code but get an output of 0 instead of 3, I should be getting three because 3 is the index of the only False value in in_tree as well, and is the index of the false value's distance in the distance array but I get 0. I am not sure where I am going wrong, maybe with what I am returning?

I am implementing a Graph class comparing breadth-first search with Prim's algorithm, and I have my code:

When I want to print an empty array of the Boolean (reference type), the result is as output #1. But when I want to print a primitive boolean type empty array, output #2 is the result. I know that the toString() method in the Object class is running by default. The default implementation of this method is as follows: