The.Algorithm.Design.Manual.Springer-Verlag.1998

Breadth-First Search
``discovered''
for each do
process edge (u,v) as desired
if state[v] = ``undiscovered'' then
state[u] = ``completely-explored''
state[v] =
p[v] = u
enqueue[Q,v]
The graph edges that do not appear in the breadth-first search tree also have special properties. For undirected graphs, nontree
edges can point only to vertices on the same level as the parent vertex or to vertices on the level directly below the
parent. These properties follow easily from the fact that each path in the tree must be the shortest path in the graph. For a
directed graph, a back-pointing edge can exist whenever v lies closer to the root than u does.
The breadth-first search algorithm above includes places to optionally process each vertex and edge, say to copy them, print
them, or count them. Each vertex and directed edge is encountered exactly once, and each undirected edge is encountered
exactly twice.
Next: Depth-First Search Up: Traversing a Graph Previous: Traversing a Graph
Algorithms
Mon Jun 2 23:33:50 EDT 1997
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