Problem
1. By using a type def, we can write one version of the program that implements either a vector-based solution or a list-based one. Write and test this version of the program.
2. Look again at the driver functions you wrote in the previous exercise. Note that it is possible to write a driver that differs only in the declaration of the type for the data structure that holds the input file. If your vector and list test drivers differ in any other way, rewrite them so that they differ only in this declaration.