Python Data Structures and Algorithms

Adjacency list

A simple list can be used to present a graph. The indices of the list will represent the nodes or vertices in the graph. At each index, the adjacent nodes to that vertex can be stored:

The numbers in the box represent the vertices. Index 0 represents vertex A, with its adjacent nodes being B and C.

Using a list for the representation is quite restrictive because we lack the ability to directly use the vertex labels. A dictionary is therefore more suited. To represent the graph in the diagram, we can use the following statements:

    graph = dict()     graph['A'] = ['B', 'C']     graph['B'] = ['E','A']  graph['C'] = ['A', 'B', 'E','F'] ...