wolffd@0: function order = topological_sort(A)
wolffd@0: % TOPOLOGICAL_SORT Return the nodes in topological order (parents before children).
wolffd@0: % order = topological_sort(adj_mat)
wolffd@0: 
wolffd@0: n = length(A);
wolffd@0: indeg = zeros(1,n);
wolffd@0: zero_indeg = []; % a stack of nodes with no parents
wolffd@0: for i=1:n
wolffd@0:   indeg(i) = length(parents(A,i));
wolffd@0:   if indeg(i)==0
wolffd@0:     zero_indeg = [i zero_indeg];
wolffd@0:   end
wolffd@0: end
wolffd@0: 
wolffd@0: t=1;
wolffd@0: order = zeros(1,n);
wolffd@0: while ~isempty(zero_indeg)
wolffd@0:   v = zero_indeg(1); % pop v
wolffd@0:   zero_indeg = zero_indeg(2:end);
wolffd@0:   order(t) = v;
wolffd@0:   t = t + 1;
wolffd@0:   cs = children(A, v);
wolffd@0:   for j=1:length(cs)
wolffd@0:     c = cs(j);
wolffd@0:     indeg(c) = indeg(c) - 1;
wolffd@0:     if indeg(c) == 0
wolffd@0:       zero_indeg = [c zero_indeg]; % push c 
wolffd@0:     end
wolffd@0:   end
wolffd@0: end