Computer Science 180
|Live Archive Ref#:||3391|
Thursday, 8 March 2012, 10:00am
|Submission Deadline:||Friday, 9 March 2012, 11:59pm|
Use of a std::list and iterators.
The pre-lab requirement must be completed and submitted individually.
The remainder of the lab activity should be completed working in pairs. One person should submit the result, making sure that both partners' names are clearly identified in that submission.
Please make sure you adhere to the policies on academic integrity in this regard.
Read the complete problem description and then determine what the expected output should be if given the following input:
|Prelab input:||Prelab output:|
A 1 20
A 2 20
A 3 30
A 4 30
A 5 1
A 6 19
A 49 1
A 48 1
R 43 A 47 1
A 46 1
A 45 1
A 44 1
A 43 1
A 42 6
A 49 1
A 48 1
A 47 1
Agnes C. Mulligan is a fanatical bibliophile – she is constantly
buying new books, and trying to find space for those books. In
particular, she has a shelf for her “to be read” books, where she puts
her newest books. When she decides to read one of these books, she
removes it from the shelf, making space for more books. Sometimes,
however, she buys a new book and puts it on the shelf, but because of
limited space, this pushes one or more books off the shelf at the other
end. She always adds books on the left side of the shelf, making books
fall off the right side. Of course, she can remove a book from any
location on the shelf when she wants to read one.
Your task will be to write a simulator that will keep track of books
added and removed from a shelf. At the end of the simulation, display
the books remaining on the shelf, in order from left to right. Books in
each simulation will be identified by a unique, positive integer, 0
< I ≤ 100. There are three
events in the simulation:
Input: The input file will
contain data for one or more simulations. The end of the input is
signalled by a line containing -1. Each
simulation will begin with the integer width of the shelf, s, 5 ≤ s ≤ 100, followed by a series of add and remove events. An add event is a single line
with an upper case 'A'
followed by the book ID, followed by the integer width of the book, w, 0 < w ≤ s. A remove event is a single
line beginning with an upper case 'R'
followed by the the book ID. Finally, the end event is a line
containing only a single upper case 'E'. Each number in an event is
preceded by a single blank.
Output: For each simulation
case, print a single line containing a label (as shown in the output
sample), followed by the
list of IDs of books remaining on the shelf, in order
from left to right.
|Example input:||Example output:|
A 6 5
A 42 3
A 3 5
A 16 2
A 15 1
A 49 6
A 48 2
A 1 1
A 2 1
A 3 1
A 4 1
A 5 1
A 6 1
A 7 4
PROBLEM 1: 15 3
This was a more difficult programming contest problem than the ones we have seen in our earlier labs. By the end of a five-hour contest, less than 50% of the teams had successfully solved it, and the average solving time for those who finished it was over 3 hours into the contest. That said, it is a rather straightforward problem with proper use of data structures.
The basic simulation sounds most like a queue, with new books placed on one end of the shelf and old books falling off the other end of the shelf. However, the rules also allow Agnes to remove a book from an arbitrary position. So for this reason, we are going to use a list rather than a queue. We will store an iterator for each book that is inserted, marking its position to facilitate a later removal. For each trial of the simulation, we recommend that you declare the following variables:
Notes of warning: