FormationControlSimulation/SOURCE/networks-toolbox/BFS.m

43 lines
1.1 KiB
Matlab
Raw Normal View History

2019-06-17 14:31:50 +07:00
% Simple implementation of breadth-first-search of a graph.
% Returns a breadth-first-search tree.
%
% INPUTs: adjacency list (nxn), "adjL"
% start node index, "s"
% end node index, "t"
% OUTPUTs: BFS tree, in adjacency list {} format (directed)
% (This is the tree that the algorithm walks in
% search of the target. If the target is not found,
% this tree is effectively a spanning tree of the
% entire graph.
%
% GB: last updated, Nov 8 2014
function T=BFS(adjL,s,t)
discovered=[s]; % mark visited
q=[s]; % add to queue
T=cell(1,length(adjL)); % initialize search path/tree
if s==t
printf('BFS(): The start and the end node are the same.\n')
return
end
while not(isempty(q))
j=q(1); q=q(2:length(q)); % pop the front
neigh=adjL{j};
for nn=1:length(neigh)
if isempty(find(discovered==neigh(nn)))
T{j}=[T{j}, neigh(nn)];
if neigh(nn)==t
return
end
discovered=[discovered, neigh(nn)];
q=[q, neigh(nn)];
end
end
end
printf('BFS(): Target node not found.\n')