43 lines
1.1 KiB
Matlab
43 lines
1.1 KiB
Matlab
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% Simple implementation of breadth-first-search of a graph.
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% Returns a breadth-first-search tree.
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%
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% INPUTs: adjacency list (nxn), "adjL"
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% start node index, "s"
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% end node index, "t"
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% OUTPUTs: BFS tree, in adjacency list {} format (directed)
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% (This is the tree that the algorithm walks in
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% search of the target. If the target is not found,
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% this tree is effectively a spanning tree of the
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% entire graph.
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%
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% GB: last updated, Nov 8 2014
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function T=BFS(adjL,s,t)
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discovered=[s]; % mark visited
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q=[s]; % add to queue
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T=cell(1,length(adjL)); % initialize search path/tree
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if s==t
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printf('BFS(): The start and the end node are the same.\n')
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return
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end
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while not(isempty(q))
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j=q(1); q=q(2:length(q)); % pop the front
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neigh=adjL{j};
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for nn=1:length(neigh)
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if isempty(find(discovered==neigh(nn)))
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T{j}=[T{j}, neigh(nn)];
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if neigh(nn)==t
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return
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end
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discovered=[discovered, neigh(nn)];
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q=[q, neigh(nn)];
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end
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end
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end
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printf('BFS(): Target node not found.\n')
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