CSc 352代写、c++代写代做、代写linked lists、代做C++程序语言

日期：2019-04-27 11:07

CSc 352 (Spring 2019): Assignment 11

Due Date: 11:59PM Wed, May 1

The purpose of this assignment is to work with linked lists, memory allocation, command line

arguments, reading from a file, using free(), representing graphs, and doing more complicated

manipulation of pointers.

General Requirements

1. Your C code should adhere to the coding standards for this class as listed in the

Documents section on the Resources tab for Piazza. This includes protecting against

buffer overflows whenever you read strings.

2. Your programs should indicate if they executed without any problems via their exit

status, i.e., the value returned by the program when it terminates:

Execution Exit Status

Normal, no problems 0

Error or problem encountered 1

3. Under bash you can check the exit status of a command or program cmd by typing the

command "echo $?" immediately after the execution of cmd. A program can exit with

status n by executing "exit(n)" anywhere in the program, or by having main() execute

the statement "return(n)".

4. Remember your code will be graded on lectura using a grading script. You should test

your code on lectura using the diff command to compare your output to that of the

example executable.

5. Your code must show no errors when run with valgind.

6. You must free all your allocated memory before your program exits.

Testing

Example executables of the programs will be made available. You should copy and run these

programs on lectura to test your program’s output and to answer questions you might have about

how the program is supposed to operate. Our class has a home directory on lectura which is:

/home/cs352/spring19

You all have access to this directory. The example programs will always be in the appropriate

assignments/assg#/prob# subdirectory of this directory. They will have the same name as the

assigned program with “ex” added to the start and the capitalization changed to maintain

camelback. So, for example, if the assigned program is theBigProgram, then the example

executable will be named exTheBigProgram. You should use the appropriate UNIX

commands to copy these executables to your own directory.

Your programs will be graded by a script. This will include a timeout for all test cases. There

must be a timeout or programs that don’t terminate will cause the grading script to never finish.

This time out will never be less than 10 times the time it takes the example executable to

complete with that test input and will usually be much longer than that. If your program takes an

exceedingly long time to complete compared to the example code, you may want to think about

how to clean up your implementation.

Makefiles

You will be required to include a Makefile with each program. Running the command:

make progName

should create the executable file progName, where progName is the program name listed for the

problem. The gcc commands in your Makefile that create the object files must include the -Wall

flag. Other than that, the command may have any flags you desire.

Submission Instructions

Your solutions are to be turned in on the host lectura.cs.arizona.edu. Since the assignment will

be graded by a script, it is important you have the directory structure and the names of the files

exact. Remember that UNIX is case sensitive, so make sure the capitalization is also correct. For

all our assignments the directory structure should be as follows: The root directory will be named

assg#, where # is the number of the current assignment. Inside that directory should be a

subdirectory for each problem. These directories will be named prob# where # is the number of

the problem within the assignment. Inside these directories should be any files required by the

problem descriptions.

To submit your solutions, go to the directory containing your assg11 directory and use the

following command:

turnin cs352s19-assg11 assg11

Problems

prob1: bacon

Write a program called bacon which calculates the Bacon score

(https://en.wikipedia.org/wiki/Six_Degrees_of_Kevin_Bacon ) of various actors based on the

information given in an input file. Kevin Bacon is a movie actor and the Bacon score for any

movie actor is the number of movies it takes to connect Kevin Bacon with that actor. The

definition is as follows:

Kevin Bacon has a Bacon score of 0

Any actor who was in a movie with Kevin Bacon has a Bacon score of 1

For any actor X, if the lowest possible Bacon score of any actor X has been in a movie

with is N, the X's Bacon score is N + 1

It may be hard to follow the outline above, but the concept is not that deep. Read through the

wiki page linked to above if you are confused.

Basically, this is a graph problem. The actors are the vertices. The edges connecting the actors

are movies. There is an edge between the vertices representing actors A and B if and only if A

and B appeared in a movie together. An actor's Bacon score is then the smallest number of edges

connecting the actor to Kevin Bacon.

Invocation: Your program will be invoked with a required argument giving the file name

of a text file containing movie names and cast lists and an optional flag to tell the

program whether to print out just the Bacon score or to print out the score together with

the path that generated it. The invocation will look like:

bacon [-l] inFile

where inFile is the name of a file which contains the movie list from which you will

build your graph and –l (that's a lowercase L) is an optional flag. To make our program

"UNIX like" we will allow the arguments to appear in any order and the option flag may

be specified multiple times. Here are some examples of legal invocations:

bacon myFile –l

bacon –l –l myFile

bacon myFile

The following would be illegal invocations:

bacon –l //has no file specified

bacon fileName fileName //too many arguments

bacon –ll myFile //not a legal option

If the invocation is illegal, you should print an error message to stderr indicating how the

program is used, and exit with a status of 1. If you are confused about what is legal and

what is not, experiment with the example executable.

Movie File: The movie file whose name is given as a command line argument will

contain a list of movies and their cast lists. The format of the file is as follows:

Move: <name of movie>

<actor 1>

<actor 2>

<actor n>

Movie: <name of movie>

<actor 1>

. . .

where the actors listed (one per line) after the movie name are the actors in that movie.

An example input file is in the subdirectory for this project of the class home directory on

lectura. The file may contain blank lines (lines containing only white space) and these

should be ignored. A single space will follow the keyword "Movie:". The name of the

movie is considered to be the string starting at the character beyond that space and

continuing until the end of the line but NOT including the '\n'. The actor's name is

everything on the line except for the possible newline ('\n') at the end. To simplify the

program, do not worry about trimming white space from the ends of the lines (other than

the '\n') or capitalization. In other words the actor's "John Wayne", "John Wayne ", "john

wayne", and " John Wayne" can all be considered to be different by your program.

Behavior: After reading the file of cast lists and creating your graph, your program will

do the following:

1. read in a line from stdin containing an actor's name

2. compute the Bacon score for that actor (using a breadth first search)

3. print the Bacon score (and the connecting actors and movies if –l option invoked)

to stdout according to the format specified below.

until no further input can be read.

? Assumptions: You can assume the following:

o The movie file, if it exists, is in correct format. In other words you may assume

the first nonblank line contains a movie name. You may also assume that if a line

starts with "Movie: ", then the line continues with some name. Note that since

blank lines are legal, and empty file is in fact a legal movie file.

Output: Output should be printed to stdout. To print out the score, use the format

printf("Score: %d\n", score)

where score is the calculated Bacon score. If there is no path between the actor and Kevin

Bacon, your program should print "Score: No Bacon!" on a single line.

If the actor queried is not in the graph, print a message to stderr and continue reading

queries. As always, whenever you print to stderr, when your program finally exits it

should exit with a status of 1.

The –l option

If the –l option is specified when the program is invoked, your program should print the

list of movies and actors connecting the queried actor to Kevin Bacon. The format for this

output should be

<Queried Actor>

was in <Movie Name> with

<Actor>

was in <Movie Name> with

<Actor>

. . .

was in <Movie Name> with

Kevin Bacon

Keeping track of this list is more difficult and only 10% of the test cases will involve this

option and they will be for extra credit. In other words you can still get 90/90 (100%) on

the assignment even if you fail to implement the –l option (you must still recognize an

invocation with the –l option as legal though), or 100/90 if you correctly implement the –l

option. Also note that while the Bacon score is unique, the list printed out may not be.

This means that if you are testing this option you may end up with a different output than

the example executable and still be correct. Don't worry about getting the same list as the

example as long as your list is correct. When I test this part of the program I will use test

cases that have only one path to generate the Bacon score. You may want to create such

test cases yourself. (The example movie file should do.)

? Data Structures:

Once again you will use linked lists to represent the graph. The vertices of the graph will

be the actors. The edges will be the movies. If you are implementing the –l option the

edges will need to contain the movie name.

There are certainly variations on this. I used a linked list of actors. Each actor contains a

linked list of movies (nodes which point to a movie). Each movie contains a linked list of

actors (nodes pointing to an actor).

The Algorithm:

A depth first search will not work here. A depth first search finds if there is a path

between two vertices. We want to find the shortest path between two vertices. To

accomplish this, we will use a breadth first search. A depth first search recursively

searches all the children of each vertex. A breadth first search puts all the children on a

queue. This way all the children are search before the grandchildren, etc. Here is the

algorithm for a breadth first search:

BFS(Start, Target)

mark Start as queued

set level of Start to 0

add Start to the queue

while queue is not empty do

Take A from top of queue

For all children C of A do

if C == Target

return level of A + 1 //found, score A.level + 1

if C not queued

mark C as queued

set level of C to level of A + 1

add C to queue

return Target not found //If you get through loop without

//finding Target, there is no

//path from Start to Target

Note that in C you will have to implement this queue with a linked list. Don't forget to

free it again after you're done using it.

Here's a hint for implementing the –l option. It requires you be able to trace the path from

Start to Target. If some actor A is put on the queue when looking at the children of some

actor B, the path to A comes from B. If your structure for nodes of the queue contains a

link to this "parent" node, then you can following these links from the queue node for the

Target back to the queue node for the Start. (i.e. It records your path.)

Error Conditions:

o Fatal errors: Bad invocation of program; input file cannot be opened for reading.

o Non-fatal errors: Queried actor is not in the graph.