CS360 -- Lab 1

  • Jian Huang
  • CS360
  • Url: http://www.cs.utk.edu/~huangj/cs360/360/labs/lab1/lab.html
    This is a lab that makes sure that you have red-black trees, dllists and fields down. If you are not yet familiar with Dr. Plank's fdr library (or need to brush up on it!), read Dr. Plank's lecture notes about libfdr.

    Your job in this lab is to write the program famtree. Famtree takes a description of people and their relationships to one another on standard input. These descriptions must be in a special format, which will be described below. An example is in the file fam1, which represents a family composed of Bob and Nancy, and their three chidren Frank, Lester and Diana.

    Famtree takes such a description, and prints out complete information on all of the people in the file. This consist of, for each person, their sex (if known), their father, mother and children. Therefore fam1output contains valid output of famtree on fam1.

    The format of the input file is as follows. Lines must either be blank, or have one of following first words:

    Famtree has two other features. First, it prints out the people in a structured order. That is, no person can be printed out until both of their parents have been printed out. If this is impossible (as, for example, in cyclefam), then famtree identifies this fact.

    The second feature of famtree is that it allows for redundancy, but it infers as much as it can. For example, redundant has a few lines that are redundant. For example, line 3 is redundant because Fred must be male by virtue of being Joe's father. Moreover, line 7 is redundant because line 2 already specified Fred as Joe's father. The file nonredundant is the minimal file specifying the same family.

    Working example

    The class directory of lab1 is ~cosc360/lab1/. Get everything you need from that directory. There is also a working example of famtree. Try it out on the input files in this directory. Other input files are: You should make your output work exactly like famtree's.

    Help

    I'm going to give rather detailed help here. In fact, I basically "give away" how to do the lab. This is so that you understand the correct structure of the program. If you think you can do this without any help, and don't want the answer given away, please don't read this, and have fun! I'd recommend that you at least think about how you'd do it with no help before you read further. However, if you want some help, read on.

    You will have a struct for a person (mine is called a Person). That struct will have the following fields:

    Your program will work in three phases:

    1. Reading the information into the structs. You should have a red-black tree (mine is called people) that contains all the people. It is keyed on each person's name, and the val fields are the persons' Person structs. You use an IS to read standard input.

      Each time you read a line that has a name (i.e. PERSON, FATHER, MOTHER, FATHER_OF and MOTHER_OF) you test to see if the person with that name is in the people tree. If not, you create the struct and insert it.

      Whenever you process a line that needs to create some links (i.e. FATHER, MOTHER, FATHER_OF and MOTHER_OF), you first check to see if the link exists and is correct. If incorrect, you flag an error. If correct, you do nothing. If the link doesn't exist, you should create it in both the parent and the child.

      When you're done with this phase, you'll have a red-black tree with all people in it, and all the people will have the correct links to their parents and children.

    2. Testing the graph for cycles. The graph is messed up if there is a cycle in it. In other words, if a person can be his/her own ancestor or descendant, than there is a problem. Testing for cycles is a simple depth-first search, which you should have learned in CS302. To test if a person is his/her own descendant, the following pseudocode will work: 
           /* assume that there is an integer field called "visited" 
        in the Person struct, and that this field is initialized 
        to zero for all people */

     is_descendant(Person *p)
     {
       if (p->visited == 1) return 0;  /* I.e. we've processed this 
                                               person before and he/she's ok */
       if (p->visited == 2) return 1;  /* I.e. the graph is messed up */
       p->visited = 2;
       for all children of p do {
         if is_descendant(child) return 1;
       }
       p->visited = 1;
       return 0;
     }
    3. Printing out the graph. If you want to forego the final 20% of the lab, just traverse the people tree and print out each person. Otherwise, this is a kind of breadth-first search. What you do is create a queue (which will be a Dllist called toprint. You can initially put all people into toprint, or you can just put all people who have no parents.

      Then you execute a loop that does the following: 

      /* assume that there is an integer field called "printed" 
   in the Person struct, and that this field is initialized 
   to zero for all people */
 
while toprint is not empty
  take p off the head of toprint
  if p has not been printed, then 
    if p doesn't have parents, or if p's parents have been printed then
      print p
      for all of p's children, put the child at the end of doprint
    end if
  end if
end while
    Enjoy!