+1 vote
252 views

The following algorithm (written in pseudo-pascal) work on an undirected graph G

program Explore (G)
procedure Visit (u)
begin
if Adj (u) is not empty
{comment:Adj (u) is the list of edges incident to u}
then
begin
Select an edge from Adj (u);
Let edge be e=(u, v)
Visit (v);
end
else
mark u as a finished vertex and remove u from LIST
{Comment: LIST is the set of vertices in the graph}
end;
begin
While LIST is not empty
do
begin
Let v ∊ LIST;
Visit (v);
end
end.

Note: Initially Adj(u) is the list of all edges incident to u and LIST is the set of all vertices in the graph. They are globally accessible.

(a) What kind of subgraphs are obtained when this algorithm traverses the graphs $G_{1}$ and $G_{2}$ shown in Fig.(6) and Fig.(7) respectively?  (b) What is the commonly Known traversal of graphs that can be obtained from the subgraphs generated by Program Explore?

(c) Show that the time complexity of the procedure is $O (v + e)$ for a graph with $v$ vertices and $e$ edges, given that each vertex can be accessed and removed from LIST in constant time. Also show that all edges of the graph are traversed.

edited | 252 views
+1
  While LIST is empty
do
begin
Let v ∊ LIST;
Visit (v);

Is it possible that there is a typo here  and it is actually

  While LIST is NOT empty
0
yes