Graph Representation Using an Adjacency List Summary The graph abstract data type is very useful for identifying relationships between entities. Graphs can be used to represent navigation on a map, with the entities being the way-points and the connections between the way-points being the named routes, with additional attributes of distance and travel time. Graphs can also be used to represent states and state transitions for finite state diagrams. Both maps and finite state diagrams benefit from a directed graph, where relationships are directional. There are also undirected graphs, which can be used to model such things as molecular structures, where the atoms are the entities and the connections between them are the chemical bonds. The following example shows an implementation of an undirected graph with a fixed number of entities. A fixed length graph is an efficient representation when the number of entities you are modeling will not grow, such as when you are modeling the...