Need help debugging this code in Matlab

Question

I have the following code

B=[1 2 3; 10 20 30 ; 100 200 300 ; 500 600 800];
A=[100; 500; 300 ; 425];
SA = sum(A);
V={}; % number of rows for cell V = num of combinations -- column = 1                
n = 1;
 arr =  zeros(1,length(B))
for k = 1:length(B)                    
    for idx = nchoosek(1:numel(B), k)'  
       rows = mod(idx, length(B))
       if ~isequal(rows, unique(rows)) %if rows not equal to unique(rows)
           continue  %combination possibility valid      
       end %Ignore the combination if there are two elements from the same row 
       B_subset = B(idx)
       if (SA + sum(B_subset) <= 3000) %if sum of A + (combination) < 3000
           rows( rows==0 )=4
           arr(rows) = B_subset(:)
           V(n,1) = {arr}
           n = n + 1
            arr =  zeros(1,length(B))
        end
    end
end

The combinations are supposed to be valid if the sum of A and some values of B are less than 3000.

Problem with my code is, the last value of B, B(3,3) , is only accounted for once in the code.

If you run the code, you will notice one cell of V containing [0;0;0;800] at row 12. But there are other combinations possible as well such as [1;0;0;800] . Where SA + (1 + 800) < 3000 , however the code does not print this possibility.

I cannot figure out why, can someone please help me debug this and find out why some combinations are skipped ? especially B(3,3) ?

Answer 1

I suspect that this line is not doing exactly what you intended:

if ~isequal(rows, unique(rows))

Instead, try this:

if ~isequal(length(rows), length(unique(rows)))