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# C++代写 | CPE-593 Data Structures and Algorithms

### C++代写 | CPE-593 Data Structures and Algorithms

Homework assignment 4 CPE-593 Data Structures and Algorithms
Spring 2020 Ins: Dr. Aftab Ahmad Due by 4 PM on 4/06/2020
Implement an OS scheduler to compare average waiting times for priority queue versus non-priority
queue.
Note: see the grading rubric at the end on the next page.
1. Imagine n jobs in an Operating System queue as an array A of integers, each element being a random
number between 1 and 100. A[i] is the size of job i in microseconds.
2. Copy the array A into an array B. Sort B using quicksort. Measure the time in microseconds that it
takes to sort the array B. Divide this time by n. This is the sorting time per job.
3. Reverse-copy B into a third array C. In other words, C[i] = B[n-1 – i] for i = {0..n-1}. Now you have
three arrays A, B and C. Array A has the jobs listed in the order of arrival, B listed in sorted order of the
job size and C in reverse-sorted order.
4. The waiting time for job i is the sum of the sizes of all jobs A through A[i-1]. The queueing time
of job i is the waiting time plus the job size A[i]. The average queueing time is the sum of queueing
times of all the n jobs divided by n. Calculate the average queueing times for all the three cases; nonpriority, priority (which is same as max-priority), and reverse-priority (which is same as min-priority).
For priority and reverse-priority queues (B and C) add the sorting time per job to the calculated average
waiting/queueing time. We are assuming that reverse-copying time is negligible.
5. Find the average queueing times for the three cases for n = 10 through 1010 with a step of 100. Print
the actual (not average) waiting times (not queueing times) of three jobs for all the three cases for
element numbers n/3, 2n/3 and n. Print the three values for A, B and C in an output file
<LastNameFirstInitial_4.dat>. This is something similar to what we did in assignment # 1. This time,
we are not using random indexes but deterministic indexes so that we can compare the three cases.
6. Use gnuplot to plot the average queueing times using lines of different colors and proper labels,
such as max-priority, no-priority, min-priority. The plot title should be ‘Average queueing time for
priority queueing’. There should be a key for all the three plot titles. Copy this multiplot and the data
from *.dat file above into a PDF file using same naming convention. Add your observation from (5)
and from the plots in a few sentences (two sentences will be good enough).
7. Compress the three files <YourLastNameFirstInitial_4.cpp>, <YourLastNameFirstInitial_4.dat> and
<YourLastNameFirstInitial_4.PDF> into one file <YourLastNameFirstInitial_4.zip> or something such
and submit this compressed file as your assignment.
In this assignment, you are not required to use HEAP to implement the queues, but you are welcomed
to do so. 