Graph

A graph consists of a set of nodes (or Vertices ) and a set of arc (or edge ). Each arc in a graph is specified by a pair of nodes. A node n is incident to an arc x if n is one of the two nodes in the ordered pair of nodes that constitute x. The degree of a node is the number of arcs incident to it. The indegree of a node n is the number of arcs that have n as the head, and the outdegree of n is the number of arcs that have n as the tail.

The graph is the nonlinear data structure. The graph shown in the figure represents 7 vertices and 12 edges. The Vertices are { 1, 2, 3, 4, 5, 6, 7} and the arcs are {(1,2), (1,3), (1,4), (2,4), (2,5), (3,4), (3,6), (4,5), (4,6), (4,7), (5,7), (6,7) }. Node (4) in figure has indegree 3, outdegree 3 and degree 6.