Pathfinding | Many pathfinding algorithm | Learning library

When I run my code it throws a segmentation fault and I have tried rewriting the code several times. Still to no avail, it won't even run. The segmentation fault happens as soon as my program is launched. What it's supposed to do is print a path on screen using the ncurses library in Linux, from the given coordinates. Here is the problematic snippet with the lines where gdb said the segmentation fault was, also it (snippet) reproduces the problem.

EDIT: This will help explain what I'm trying to do, but using dynamic arrays. Breadth First Search

EDIT 2: The variable frontier is supposed to keep track of the X and Y values at a specific index. The add_neighbors function is there to add all four neighbors (providing they aren't already added) to the frontier and came_from arrays.

frontier[index][0] is X value.
frontier[index][1] is Y value.

The before the first while loop I set the start position x1 and y1. During the first while loop, it increments getting the new coordinates from the frontier, then processing and adding to came_from array.

For example:
(x1,y1) (x1+1,y1)
(x1,y1+1) (x1+1,y1+1)
(x1,y2) (x2,y2)

I'm trying to get from (x1,y1) to (x2,y2). Sure hope that explains it better. What I'm trying to implement is a Breadth First Search (BFS) algorithm. Using two arrays, one is frontier (keeps track of visited positions) and came_from (keeps track of X and Y the path from x1,y1 to x2,y2). Updated the code to reflect the first answer. Plus added a comment to explain where the error might be, not really sure but I've been debugging it. It looks like the came_from array never gets set with x and y.

The Code:

I am new to C#/Unity and looking for a way to slow down onDrawGizmos. Currently everything works great.

In my code below, the value passed by the for loop is not in the list that is being iterated. I am coding a simple pathfinding function in which a start and an end point are passed, and the output is the pathway to get from the start point to the end point. The dictionary called connections has a key for all the points on the map, with the value being a list of all the other points it is connected to. You can only get from one point to another via the NODEs (think Nodes are like roads and the letters are houses).

In this case, I input a start point of 'A' and an end point of F. The expected output is:

I am trying to make a maze/horror game. I used an online template in the Roblox library as my enemy. I used pathfinder as you will see in the code below. It's finding me like it's supposed to, except it only goes for my LAST position. As you can see in the image below, it completely skipped me, went to my LAST position, then started chasing me. I don't know why it only goes for my last position, and not my current position.

I have an array such as def list = ["pathfinding", " Gameplay", "Community"] which I would like to iterate and eliminate the whitespace at the beginning of each element. So I though it would be easy using something like:

There is a TLDR at the bottom. I have a python class as follows which is used to make nodes for D* Pathfinding (Pathfinding process not included):

I was doing a pathfinding visualizer in pygame and I pretty much finished but there's still one thing that I do not like about the algorithm part of it and it's the fact that when you press the visualize algorithm button it shows you the shortest path in yellow and all of the nodes the algorithm has visited ever in light blue but it shows you instantaneously and I want it to color the nodes accordingly step by step to actually reach the effect of visualizing (like in here https://clementmihailescu.github.io/Pathfinding-Visualizer/#), I tried to write some code in the function that seemed like it would have worked as intended but it didn't, here is the code:

I'm trying to implement a pathfinding algorithm visualizer using a yield function on my algorithm that yields the list of visited nodes each time it visits one at the end of my function: