Traversal

One of the useful operations performed on a graph is its traversal, that is, visiting all of the nodes in some particular order. Of course, the afore mentioned problem can be solved in various ways, such as using depth-first search (DFS) or breadth-first search (BFS) approaches. It is worth mentioning that the traversal topic is strictly connected with the task of searching for a given node in a graph.

Depth-first search

The first graph traversal algorithm described in this chapter is named DFS. Its steps, in the context of the example graph, are as follows:

Of course, it can be a bit difficult to understand how the DFS algorithm operates just by looking at the preceding diagram. For this reason, let's try to analyze its stages.

In the first step, you see the graph with eight nodes. The node 1 is marked with a gray background (indicating that the node has been already visited), as well as with a red border (indicating that it is the node that is currently being visited). Moreover,...