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Buyer Summary:
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1
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5 posted 1 paid |
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Miami, OK, United States
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| Member Since: |
November 3, 2007 |
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Description
I. The Double-Ended List
The double-ended list, or Dlist, is a templated container. It
supports the following operational methods:
* isEmpty: a predicate that returns true if the list is empty,
false otherwise
* insertFront/insertBack: insert an object at the front/back of
the list, respectively
* removeFront/removeBack: remove an object from the front/back of
a non-empty list, respectively; throws
an exception if the list is empty.
Note that while this list is templated across the contained type, T,
it inserts and removes only pointers-to-T, not instances of T. This
ensures that the Dlist implementation knows that it owns inserted
objects, is responsible for copying them if the list is copied, and
destroying them if the list is destroyed.
The complete interface of the Dlist class is provided in dlist.h. The
code is replicated here for your convenience. You may not modify
dlist.h in any way.
The definition of "node", the private type for elements of the
container list, is given in the private section of class Dlist. This
is so that clients of the class cannot use the type.
In addition to the five operational methods, there are the usual four
maintenance methods: default constructor, copy constructor, assignment
operator, and destructor. Be sure that your copy constructor and
assignment operator do *full* deep copies---including making copies
of T's owned by the list.
Finally, the class defines three private utility methods in which to
place code common to two or more of the maintenance methods.
You are to provide an implementation for each Dlist method in a file
called dlist.cpp, to be handed in with this project. We will test
your Dlist implementation separately from the other components of this
project, so it must work independently of the two applications.
Note that dlist.h includes dlist.cpp; this is because of the way that
template types work in the GNU C++ compiler. To instantate a Dlist of
pointers-to-int, for example, you would declare the list:
Dlist il;
This instructs the compiler to instantiate a version of Dlist that
contains pointers-to-int, and the compiler *at that point* compiles a
version of the Dlist template that contains such pointers-to-int.
Note also that we use the "template " syntax rather than
the "template " syntax in dlist.h. The two are equivalent,
but we believe that typename makes a bit more sense to the reader.
To compile a program that uses Dlists, you need only inclsde
"dlist.h". You do not need to name dlist.cpp on the compiler command
line, because dlist.h includes it. As an example, consider the
following simple test program, called testl.cpp.
II. RPN Calculator
The first of these applications is a simple Reverse-Polish Notation
calculator. An RPN calculator is one in which the operators appear
*after* their respective operands, rather than in between them. So,
instead of computing the following:
(2 + 3) * 5
an RPN calculator would compute this equivalent expression:
2 3 + 5 *
RPN notation is convenient for several reasons. First, no parentheses
are necessary---the computation is always unambiguous. Second, such a
calculator is easy to implement given a stack. This is particularly
useful, because it is possible to use the DList as a stack.
The calculator is invoked with no arguments, and starts out with an
empty stack. It takes its input from the standard input stream, and
writes its output to the standard output stream. Here are the
commands your calculator must respond to:
a number has the form: one or more digits [0--9]
optionally followed by a decimal point and one or
more digits. For example, 3 4.56 and 0.12 are
all numbers, but -2, 1., and abc are not. A
number, when entered, is pushed on the stack.
Always valid.
+ pop the top two numbers from the stack, add them
together, and push the result. Requires a stack
with at least two operands.
- pop the top two numbers from the stack, subtract
the first popped number from the second, and push
the result. Requires a stack with at least two
operands.
* pop the top two numbers from the stack, multiply
them together, and push the result. Requires a
stack with at least two operands.
/ pop the top two numbers from the stack, divide
the second popped number by the first, and push
the result. Requires a stack with at least two
operands.
n negate: pop the top item, multiply it by -1, and
push the result on the stack. Requires a stack
with at least one operand.
d duplicate: pop the top item and push two copies
of it. Requires a stack with at least one
operand.
r reverse: pop the top two items, push the first
popped item, then the second. Requires a stack
with at least two operands.
p print: print the top item to standard output,
followed by a newline. Requires a stack
with at least one operand. Leaves the stack
unchanged.
c clear: pop all items from the stack. Always
valid.
a print-all: print all items from the stack in one
line, from top-most to bottom-most, each
separated by a single space, followed by a
newline. Always valid. Leaves the stack
unchanged.
q quit: exit the calculator. Always valid.
Each command is separated by whitespace.
You may not assume that user input is always correct. There are three
error messages to report.
1) If a user enters something other than one of the commands above,
leave the stack unchanged, advance to the next whitespace
character, and print the following message:
cout << "Bad input\n";
2) If a user enters a command that requires more operands than are
present, leave the stack unchanged, advance to the next
whitespace character, and print the following message:
cout << "Not enough operands\n";
3) If a user enters the divide command with a zero on the top of
the stack, leave the stack unchanged, advance to the next
whitespace character, and print the following message:
cout << "Divide by zero\n";
Note that the phrase "leave the stack unchanged" is not to be taken
literally. It is okay to pop the top two operands for division; if
the divisor is zero, be sure push them back before reading the next
command.
You may assume that the user will not type EOF before quitting. Here
is a short example:
[ 23 ] clip p5 -: ./calc
2
3
4
+
*
p
14
+
Not enough operands
d
+
p
28
q
Implement your calculator in a file called calc.cpp, to be handed in
when the project is due. It must work correctly with any valid
implementation of DList.
III. Call Center Simulation
The second application is a simple discrete-event simulator, modeling
the behavior of a single reservation agent at Northwest Airlines.
When a customer calls Northwest, they are asked to enter their
WorldPerks number. Calls are then answered in priority order:
customers who are Platinum Elite---those having flown 75,000 miles or
more in the current or previous calendar year---have their calls
answered first, followed by Gold (50,000), Silver (25,000), and
finally "regular" customers.
(Now you know why you can never reach a reservation agent on the
phone!)
A discrete-event simulator is so called because it considers time as a
discrete sequence of points, with zero or more events happening at
each point in time. In our simulator, time starts at "time 0", and
progresses in increments of one. Each increment is referred to as a
"tick".
A discrete-event simulator is usually driven by a script of
"independent events" plus a set of "causal rules".
In our simulator, the independent events are the set of customers that
place calls to the call center. These events are in a file. The
first line of the file has a single entry---the number of events (N)
contained in the next N lines. Each of those N lines has the
following format:
Each field is delimited by one or more whitespace characters. You may
assume that the lines are sorted by timestamp-order, from lowest to
highest. Timestamps need not be unique.
is an integer, zero or greater, that denotes the tick at
which this call comes in.
is a string; the name of the caller. This string has no
spaces.
is one of the following four strings:
"none" -- no special status
"silver" -- silver elite
"gold" -- gold elite
"platinum" -- platinum elite
is an integer, denoting the number of ticks required to
service this call.
You may assume that the input file is semantically and syntactically
correct. Your simulator must obtain this input file from the standard
input stream cin.
Your simulator will maintain four queues, one for each status level.
The simulation proceeds as follows (these are the causal rules):
* At the beginning of a "tick", announce it.
Starting tick #
* Any callers with timestamps equal to that tick number are
inserted into their appropriate queues. When a caller is
inserted, you should print a message that looks like this:
Call from Brian a silver member
(As it happens, Prof. Noble is a Silver Elite member this year.)
* After any new calls are inserted into the call queues, the
(single) agent is allowed to act.
If the agent is not busy, the agent checks each queue, in
priority order from Platinum to None. If the agent finds a call,
the agent answers the call, printing a message such as:
Answering call from Brian
This will keep the agent busy for ticks.
If the agent was already busy at the beginning of this tick, the
agent continues servicing the current client until the
appropriate number of ticks have expired.
If the agent is not busy, and there are no current calls, the
agent does nothing, and the clock advances. The program
terminates only when all listed calls have been placed, answered,
and completed.
Here is a sample input file:
---------------------------------------------
3
0 Andrew gold 2
0 Chris none 1
1 Brian silver 1
---------------------------------------------
And the output produced by running the simulator on it:
---------------------------------------------
[ 27 ] clip p5 -: ./call < sample
Starting tick #0
Call from Andrew a gold member
Call from Chris a regular member
Answering call from Andrew
Starting tick #1
Call from Brian a silver member
Starting tick #2
Answering call from Brian
Starting tick #3
Answering call from Chris
Starting tick #4
---------------------------------------------
Implement your simulator in a file called call.cpp, to be handed in
when the project is due.
IV. General Requirements
You must use the Dlist container to implement both your stack in the
calculator and your queue(s) in the call simulator. You may use any
type you see fit as the templated type in each application---however,
remember that you only insert and remove pointers-to-objects. You
must use the at-most-once invariant plus the Existence, Ownership, and
Conservation rules when using your Dlist. Therefore, you can only
insert dynamic objects.
You may not leak memory in any way. To help you see if you are
leaking memory, you may wish to #include and link against
altnew.cpp. This file replaces the new and delete operators (plain
and array versions) with an allocator that counts the number of bytes
allocated.
NOTE: this reports bytes allocated by *anything* in your program OR
anything your program *uses*. For example, if you print output to
cout, and it is buffered, the library that implements cout will
allocate memory via altnew, and those bytes will be recorded in the
total. Thus, it is perfectly acceptable for your program to exit with
non-zero allocated memory. But if, for example, altnew reports that
memory alloacted grows each time you insert an object and then remove
it, you probably have a leak.
As a side effect, this allocator will also complain about
double-frees, as well as freeing a block that was not allocated by new
or has been corrupted since then. These mechanisms are not foolproof,
but they will catch many mistakes. To the best of our knowledge,
altnew is portable, but we make no guarantees.
Please note that tools like purify or valgrind will be terribly
offended by the sleazy tricks played by the alternate allocator. If
you mix these tools, one or both will be very confused.
You must fully implement the Dlist ADT. Note that the obvious
implementations of the calculator and simulator do not exercise all of
a Dlist's functionality.
Your three files---dlist.cpp, calc.cpp, and call.cpp---will be tested
independently. Be sure that they can be compiled separately, with no
cross-file dependencies.
You may #include , , , and . No
other system header files may be included, and you may not make any
call to any function in any other library (even if your IDE allows you
to call the function without including the appropriate header file).
Input and/or output should only be done where it is specified.
You may not use goto, nor may you use any global variables that are not const.
V. Files
All files for this project live in Stacks and Queues and Lists.zip. The following are provided:
altnew.h: interface for the alternate allocator
altnew.cpp: its implementation
dlist.h: the Dlist class declaration
testl.cpp: a *very* simple list test case
sample: the sample simulator input
sample.out: the sample simulator output (use diff!)
In the end three files are need Dlist.cpp, Cal.cpp, and Call.cpp. This project needs to be complete by Monday 3:00 pm EST time and for no more than $45.
Reminder
You may not start working in this and any request before
your bid is accepted. Users who violate this policy
may have their accounts permanently suspended.
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Dhaka,
BD
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US$80
bid amount
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(206
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7 day(s)
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please check pmb
Bid Time: 11-29-2007 15:10
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Tuscaloosa,
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2 day(s)
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Please check PM.
thanks
Bid Time: 11-29-2007 07:28
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Moscow,
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US$45
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(36
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feedback |
3 day(s)
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hello. If we have weekend to work - your project would be done.
Bid Time: 11-30-2007 08:45
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Kiev,
UA
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US$40
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Consider it well-done.
Bid Time: 11-29-2007 21:05
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Herzeliya,
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US$70
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1 day(s)
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Please check PM.
Bid Time: 11-29-2007 09:38
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Wroclaw,
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US$90
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2 day(s)
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Hello, I'm sure you will be satisfied with my work. :)
Bid Time: 11-30-2007 08:45
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dhaka,
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US$50
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6 day(s)
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Please sir,
Let us have this project. We've experience on this type of work.
thanks.
Bid Time: 11-29-2007 13:14
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Lahore,
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Hello
Sir, I am the experienced programmer and designer and I am already developing the similar project and understand what you need.
Well I can negotiate on budget and time frame after your response:)
thanks,
RSC003
Bid Time: 11-29-2007 15:49
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Chittagong,
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US$75
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3 day(s)
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Please see Pm.
Bid Time: 11-30-2007 09:13
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