function W = solver1(B)

% for connecting purposes ignore pins with only one occurrence

% if sum of l1 distances to center is greater than sum of pins, ignore
% pins = unique(B(B>0));
% ignPin = zeros(size(pins));
% for idx = 1:numel(pins)
%     k = find(B == pins(idx));
%     [i,j] = ind2sub(size(B),k);
%     ci = mean(i);
%     cj = mean(j);
%     dc = sum(abs(ci-i) + abs(cj-j));
%     pB = sum(B(k));
%     ignPin(idx) = dc - pB;
% end

pinNbr = sort(unique(B(B>0)), 'descend');
[br, bc] = size(B);
neighbIdx = [ -1 br 1 -br ]; % [ ^ > v < ]
W = zeros(0,4);
for n = pinNbr'
    pinIdx = find(B == n);
    for p = pinIdx'
        neighb = p + neighbIdx;
        for k = 1:4
            N = neighb(k);
            if N > 0 && N <= br*bc && (B(N) == 0 || B(N) == n)
                p2 = N;
                neighbIdx2 = setdiff(neighbIdx, -neighbIdx(k)); % remove previous direction
                neighb2 = p2 + neighbIdx2;
                isGood = B(N) == n;
                for k2 = 1:3
                    N2 = neighb2(k2);
                    if N2 > 0 && N2 <= br*bc && B(N2) == n
                        [p2i, p2j] = ind2sub([br bc],p2);
                        [N2i, N2j] = ind2sub([br bc],N2);
                        W = [ W ; p2i p2j N2i N2j ];
                        isGood = true;
                    end
                end
                if isGood
                    [pi, pj] = ind2sub([br bc],p);
                    [Ni, Nj] = ind2sub([br bc],N);
                    W = [ W ; pi pj Ni Nj ];
                end
            end
        end
    end
end