Question Help with A*

I'm trying to implement an A* algorythm and i've run into 2 problems:
1.how do I generate the nodes? I've managed to do it for stuff like a cube, but idk how to do it for smth more complex (irly dont wanna use mesh colliders if i can)
2.should i put all the connections between nodes in a matrix or should i put in every node a list of the adjacent nodes? when the scene begins i wanna delete the nodes with no conections to others; also im thinking to add the start and end position as temporary nodes and calculate the path that way

 

I recommend watching a series of videos by Sebastian Lague about A* Pathfinding. The link to the introductory video is here.

Both of your questions are answered, including a lot more. I believe it is probably the best A* Pathfinding series on Youtube.

 

how would i do the node creation in 3d? making a 3d grid seems rather ineficient

 

You can make a graph of 3D nodes, that might save you a lot of memory compared to a grid.

 

Octree