The following is a checklist which provides a summary of the assignment. This is meant only as a supplement; please read the original assignment description.

[Michael 4/3] At one point in the original assignment, it states "Your driver program should not store the whole text string. Indeed, you only need to keep track of the most recent k characters in the string."
however...In one of my precepts I said that we will not be strictly checking this requirement, and you will notice that it has never appeared as a requirement anywhere in the checklist It is unclear in context whether this comment was talking about the warmup method or about your final sumbitted program (it appeared in the paragraph which started, "As a warmup...")
At the same time, I said that the reason for the comment is indeed that there is really no need to explicitly store the original string for most people's programs. For example, in the direct symbol table program, the flow of control is to walk through the original string and call Insert for each string you pass. In this case, there is never any other time you will need the original string, and so in this case, rather than take the space to store the whole thing, you can just do the insertions while you read in the input.
I think this is true of most of the more interesting methods too, however if you feel there is good reason to be storing the input string for your program, you are certainly free to do so. (As we said, just don't throw away space, and explain your method in the readme).

[Michael 3/30] Some performance bounds for my own implementation have been added to the bottom of this file.

[Michael 3/30] The original 'baby.txt' had some extended ascii values (accented versions of vowels with values>256), but these have now been replaced. At this point, all characters in the input files are standard ascii and thus have equivalent values between 0 and 127 inclusive.

[Michael 3/30] For this assignment, it is important to be able to generate different random trials, by changing the seed used for the random number generator.
For my program, I use random(), and thus have the following two lines at the top:

#include <sys/types.h>
#include <sys/timeb.h>

long seed=time(NULL);
srandom(seed);