As mentioned in the text, an alternative way to compute Kevin Bacon numbers is to build a graph where there is a vertex for each performer (but not for each movie), and where two performers are adjacent if they appear in a movie together (see Program 4.5.6). Calculate Kevin Bacon numbers by running breadth-first search on the performer-performer graph. Compare the running time with the running time on movies.txt. Explain why this approach is so much slower. Also explain what you would need to do to include the movies along the path, as happens automatically with our implementation.