function lo(sx,sy)
% lo(sx,sy) - play lights out
% sx,sy: board size
    L=zeros(sx,sy);

    % initialize
    init=rand(sx,sy)>=0.5;
    for x = 1:sx
       for y = 1:sy
           if init(x,y)
               L=ltoggle(L,x,y);
           end
       end
    end

    while any(any(L))
        % pintar
        lplot(L);

        % esperar clic
        [cx cy] = ginput(1);
        cx = floor(cx);
        cy = floor(cy);

        % ejecutar paso
        L=ltoggle(L, cx, cy);
    end
    lplot(L);
    text((sx+1)/2,(sy+1)/2,'YOU WIN','Color','green','FontSize',40,'HorizontalAlignment','center');
    disp('Enhorabuena');
end

function lplot(L)
    px = [0 0 1 1];
    py = [0 1 1 0];
    [sx sy] = size(L);
    clf;
    axis([1 sx+1 1 sy+1]);
    hold on;
    for x = 1:sx
       for y = 1:sy
           c = 'kb';
           fill(px+x, py+y, c(1+L(x,y)));
       end
    end
end

function L=ltoggle(L,cx,cy)
    [sx sy] = size(L);
    L(cx,cy) = ~L(cx,cy);

    if(cx-1 > 0); L(cx-1,cy) = ~L(cx-1,cy);
    else L(sx,cy) = ~L(sx,cy); end;

    if(cx+1 <= sx);L(cx+1,cy) = ~L(cx+1,cy);
    else L(1,cy) = ~L(1,cy); end;

    if(cy-1 > 0);L(cx,cy-1) = ~L(cx,cy-1);
    else L(cx,sy) = ~L(cx,sy); end;

    if(cy+1 <= sy);L(cx,cy+1) = ~L(cx,cy+1);
    else L(cx,1) = ~L(cx,1);end;
end