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)))