Algorithms in C, Part 5: Graph Algorithms, Third Edition

Chapter Eighteen Graph Search

WE OFTEN LEARN properties of a graph by systematically examining each of its vertices and each of its edges. Determining some simple graph properties—for example, computing the degrees of all the vertices—is easy if we just examine each edge (in any order whatever). Many other graph properties are related to paths, so a natural way to learn them is to move from vertex to vertex along the graph’s edges. Nearly all the graph-processing algorithms that we consider use this basic abstract model. In this chapter, we consider the fundamental graph-search algorithms that we use to move through graphs, learning their structural properties as we go.

Graph searching in this way is equivalent to exploring a maze. Specifically, ...