This document provides instructions for an assignment with 4 questions. It involves using stacks, queues, sets, maps and calculating hashcodes of strings. Students need to submit their responses by April 28th, 2016 for a total of 5 marks. Late or copied submissions will receive zero marks. The questions cover identifying real life examples of stack and queue usage, basic set operations in Java, storing and manipulating course data in a map, and writing a method to calculate string hashcodes based on a given formula.

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COLLEGE OF COMPUTING AND INFORMATICS
Assignment – 4
Course Title : Computer programming II Course Code : CS141
Important Notes: Submission Deadline: 28/04/2016, 23:59 Marks: 5
Copied Work: ZERO Late Submission: ZERO Question 1: (1 Mark)
Read about the following real life situations and decide whether
you will use a stack or a queue.
Provide valid reason of your choice.
1)
2)
3)
4)
5) A car wash facility.
Batteries in Flashlight.
Pringles (pack of chips).
Customers at Al-Baik.
Execution of a recursive method. Question 2: (1 Mark)
What is Set? Write Java code for the following operations:
1) Construct the Set 2) Add and remove an element from a HashSet
3) Test whether an element is contained in the set 4) Visiting all
Elements with an Iterator Page 1 of 3 Question 3: (1 Mark)
Suppose you have the following information about courses and the
number of students in each
course.
CS140
CS141
IT407

2. IT101
IT244
1234- 549
256
120
636
210 Write a program that store these information in a map
Remove the course IT407 with its associated value
Edit the number of students in CS140 to 433
Print all keys with their values as the following format: Question 4:
(2 Marks)
Create a class called StringHashCode which besides a main
method provides the following
method:
public static int strHashCode(String str)
This method should return the integer hash code of the string
parameter str using the formula
given below:
Hashcode = str[0]*31^(n-1) + str[1]*31^(n-2) + ... + str[n-2] *31^(1) +
str[n-1]
Here str[0] means the first character in str and str[1] means second
character of str and so on.
With n we denote the length of the string str, * means multiplication
and ^ represents the power
(exponent).
For example if str = “abc”, then we have: hashcode = ‘a’*31^2 +
‘b’*31^1 + ‘c’
Note: Using some character such as ‘b’ in arithmetic calculations
automatically replaces it with
its ASCII code. That is, you don’t need to worry about it, java will
handle it automatically.
In the main method of your class, write code to ask the user to
enter a string, then pass this string
input to the method strHashCode and print the hash code returned
by the method on the monitor

3. screen. Then, your program should print to the user: Do you want
to enter a new string (Y/N).
Based on the use choice, program should proceed.
Page 2 of 3 Following is an example run of the program:
Enter a string: Adam
Hash code for Adam is: 2035631
Do you want to enter a new string (Y/N): y
Enter a string: Eve
Hash code for Eve is: 70068
Do you want to enter a new string (Y/N): Y
Enter a string: SEU
Hash code for SEU is: 81987
Do you want to enter a new string (Y/N): n
Thank you. Exiting program execution... Page 3 of 3