Algorithms and OOD (CSC 207 2014F) : Labs
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Summary: In this laboratory, you will have an opportunity to ground your understanding of priority queues, particularly of the array-based implementation of queues. Along the way, you may think more about object-oriented design, such as the design of adapter classes.
Required Code Files:https://github.com/Grinnell-CSC207/linear
a. Add up the number of vowels in the first names of all of your group members. Make a note as to whether that number is even or odd.
b. Review the reading on linear structures.
c. Review the reading on priority queues.
a. Read through our interface for priority queues,
PriorityQueue.java
.
b. Read through the documentation on the standard Java implementation of priority queues, available at http://docs.oracle.com/javase/8/docs/api/java/util/PriorityQueue.html.
c. Discuss with your partner how you would write an adapter class to make the built in priority queues match the desired behavior of our priority queue interface.
d. Look at BuiltinPriorityQueue.java
to see how our
implementation matches your design.
Look at PriorityQueueExpt
. Summarize what the queue
should look like at each step of the first series of procedure calls.
You may also want to revisit the ReportingLinearStructure
class.
Run PriorityBasedQueueExpt
and see if you get the output that
you expect.
a. Revise PriorityQueueExpt
so that the queue gives highest
priority to the longest strings. That is, get
should
return the longest remaining string.
b. Revise PriorityQueueExpt
so that the queue gives
highest priority to the alphabetically first string.
a. Read through ArrayBasedPriorityQueue.java
. You will note
that the iterator is not yet implemented and that prioritization is not
yet implemented.
b. Make some notes to yourself as to how you might finish implementing
the put
and get
methods.
As the reading noted, there are two basic strategies for implementing priority queues in arrays.
put
method must ensure that
the elements in the array are stored in order. (You can probably
use a variant of the insert
method from insertion sort to
achieve that goal.)
get
or
peek
. (You can probably use a variant of the
indexOfSmallest
method from selection sort to
achieve that goal.)
If you came up with an odd number in the preparation, use the first of the two approaches. If you came up with an even number, use the second of the two approaches.
If you are fortunate enough to have extra time, do some of the following:
get
. The easy approach is to simply pick a random
position each time. However, that approach does not guarantee
that peek
returns the same value as the subsequent
get
. Start with the easy approach, and then see if you
can get peek
and get
to work in synchrony.