Suppose the add of the Unique program is replaced by add First and the program is run on (for example) the first chapter of Mark Twain’s Tom Sawyer. Why does the modified program run as much as 25...

Suppose the add of the Unique program is replaced by add First and the program is run on (for example) the first chapter of Mark Twain’s Tom Sawyer. Why does the modified program run as much as 25 percent slower than the program using the add (i.e., add Last) method?

Even though we don’t need to have the special cases in, for example, the indexed version of add, it is desirable to handle one or more cases in a special way. What are the cases, and why is it desirable?