I need help fixing backtracking function on code for puzzle solver.

Can't find what I'm missing in the code for this backtracking function to run correctly.

% Define the missing functions
function [imax, jmax, MaxScore] = findNextCell(P, HashRow, HashCol, HashBlock)
% Find the next cell with the least number of possible values
imax = 0; jmax = 0; MaxScore = -1;
for i = 1:16
    for j = 1:16
        if P(i,j) == -1
            score = sum(HashRow(i,:)) + sum(HashCol(j,:)) + sum(sum(HashBlock(ceil(i/4),ceil(j/4),:)));
            if score > MaxScore
                MaxScore = score;
                imax = i;
                jmax = j;
            else
                
            end
        end
    end
end
end

[Dyuman Joshi]

What is the objective here? What is the function suppossed to be doing?

What inputs are provided to it? And what are the corresponding expected outputs?

Answer 1

[Sanju]

Hi Adrian,

The code you provided seems to be missing the main function that calls the findNextCell function. Without the main function, it is difficult to determine the exact issue you are facing. However, based on the provided code, I can see that the else statement inside the inner loop is empty. This might cause unexpected behavior in your code. You should either remove the else statement or add the necessary code inside it.

Here is an example of how you can call the findNextCell function from a main function,

function mainFunction()
    % Define your input variables
    P = ... % your input matrix
    HashRow = ... % your input matrix
    HashCol = ... % your input matrix
    HashBlock = ... % your input matrix

    % Call the findNextCell function
    [imax, jmax, MaxScore] = findNextCell(P, HashRow, HashCol, HashBlock);

    % Display the results
     .......
end

Please provide more details or the complete code if you need further assistance.

Hope this helps!

Answer 2

[John]

it seems like you're trying to implement a function findNextCell that selects the next empty cell with the least number of possible values in a 16x16 grid for a puzzle solver using backtracking.

function [imax, jmax, MaxScore] = findNextCell(P, HashRow, HashCol, HashBlock)
% Find the next cell with the least number of possible values
imax = 0; 
jmax = 0; 
MaxScore = Inf;  % Initialize MaxScore to a large value
for i = 1:16
    for j = 1:16
        if P(i,j) == -1
            score = sum(HashRow(i,:)) + sum(HashCol(j,:)) + sum(HashBlock(ceil(i/4),ceil(j/4),:), 'all');
            if score < MaxScore
                MaxScore = score;
                imax = i;
                jmax = j;
            end
        end
    end
end
end

effectiveness of this function depends on how the HashRow, HashCol, and HashBlock matrices are constructed and what they represent in your puzzle solver. Ensure that these matrices are properly initialized and updated to reflect the current state of the puzzle grid.