function [M, piece] = adjacency(piece)
%Computes the upper triangular part of the adjacency matrix of a 2-d binary
%array, and numbers the squares.

warning off MATLAB:conversionToLogical
piece = int8(logical(piece));
warning on MATLAB:conversionToLogical

count = 0;
[l, w] = size(piece);

%Number the nodes
for i = 1:l
    for j = 1:w
        if piece(i, j)
            count = count + 1;
            piece(i, j) = count;
        end
    end
end

M = logical(zeros(count));

for i = 1:(l - 1)
    for j = 1:(w - 1)
        c = piece(i, j);
        if c
            d = piece(i + 1, j);
            if d
                M(c, d) = 1;
            end
            r = piece(i, j + 1);
            if r
                M(c, r) = 1;
            end
        end
    end
    c = piece(i, w);
    if c
        d = piece(i + 1, w);
        if d
            M(c, d) = 1;
        end
    end
end
for j = 1:(w - 1)
    c = piece(l, j);
    if c
        r = piece(l, j + 1);
        if r
            M(c, r) = 1;
        end
    end
end