NQueens | N-Queens Counting Algorithms in Javascript | Learning library

I'm trying to do this nQueens problem and my code looks like this:

I am new to Optaplanner. I thought I had understood what planning entities are, as well as planning variables, genuine or some inverse-kind shadow ones. I have started studying the documentation, the examples and old StackOverflow's questions, but some doubts remain.

When trying to make incremental my score calculator, I have found some unexpected methods in the IncrementalScoreCalculator interface. Together with beforeVariableChanged and afterVariableChanged, I find *EntityAdded and *EntityRemoved, which make me suspect that entity objects may be added and removed. Moreover, these methods are implemented in the NQueens documented example, but in the kind of examples I looking at, examples of distributing shifts, resources, time slots, etc., I find that the domain is designed in such a way that planning entities are expected to be modified, but not added or removed.

I don't know if the addition/removal of entity objects is something used somewhere, as in route planning problems which I haven't dove into, and if these additions and removals are explicit or implicit. So, might planning entities be added or removed by Optaplanner without being asked to?

So I am solving the N queens problem, where you have to find the number of possible solutions to have a number N queens on an NxN chess board without them being able to attack each other. I am doing it using recursive backtracking. I have implemented my solution in code already, but for some reason I am not getting the correct number of solutions, and I can't figure out why.

Here is my code:

I am quite new to tkinter(8.6) and have some experience in python(3.7.9).

I am making a program to solve the NQueens problem, the base code works and changes the values in the matrix, however when I try to configure the label when calling the method from the solver.py file, I get the error in the title. But if I call the method when testing the error does not appear.

Any ideas for a solution?

eightQueens.py

I have this error when executing my code. I looked around on other posts about this, but all these posts mention the use of () or [] where they should not be used. However, in my case I do not see that being the issue as the only thing I am trying to do is overwrite the value of an index of one list with another item of another list. This is the code I am trying to call it in:

I think I understand the point of the NQueens algorithm - you check each row for available spaces and if they exist, put a queen there, and recursively call the algorithm to the next row. Here is my algorithm (with N size 3)

There are so many questions regarding Nqueens problem here. However, my implementation is different. My code checks with the board if queen placement is possible, instead of checking with the position of the previous queen.

It goes like this:

I am trying to implement a nqueens solver with OpenMP, my serial code works fine but when I try to do task parallelism on that, I get segmentation fault or empty rows/cols.

Here is my implementation: