Recitation 5 — Graphs and StSeqs

Suppose you’re given an undirected graph G = (V, E), where V is a set of vertices (also known as nodes) and E ⊆ V 2 is a set of edges. Notice that in this definition, an edge e = {x , y} is a set of size two representing the endpoints. Thus, the edge {x , y} represents the same edge as {y, x}. Following this, we can think of representing a graph simply as an edge set. But the edge set representation doesn’t provide an efficient means to access the neighbors of a vertex. That’s why in class we looked at a different representation which we call an adjacency table. In the following, we’ll look at a simple problem that will illustrate the differences in complexity between these two common representations.