COMP9024 Assignment One

Objectives

• Give you experience with doubly linked lists

• Understand how to solve set union, set intersection and longest sublist problems

• Give you practice with time complexity analysis

• Give you further practice with C and data structures

Admin

Marks 12 marks. Marking is based on the correctness and efficiency of your code. Your

code must be well commented.

Group? This assignment is completed individually

Aims

In this assignment, you will implement a set of functions based on the doubly linked list

defined in MyDLList.c.

The functions you need to implement are shown as follows:

1. DLList *CreateDLListFromFileDlist(const char *filename). This function creates a

doubly linked list of integers by reading all integers from a text file named filename,

and returns a pointer to the doubly linked list where each node stores one integer. Assume that adjacent integers in the file filename and the standard input are

separated by one or more white space characters or a new line character.

If filename is “stdin”, CreateDLListFromFileDlist (“stdin”) creates a doubly linked list

by reading all integers from the standard input and the word end denotes the end of

input.

This function must check for invalid input. In case of invalid input, it prints an error

message “Invalid input!” and returns NULL. (2 marks)

2. void printDLList(DLList *u ). This function prints all the elements (integers) of a doubly

linked list pointed by u in the order from the first node to the last node in the list on

the standard output, one element per line. (1 mark)

3. DLList *cloneList(DLList *u). This function creates an identical copy of a doubly linked

list u and returns a pointer to the list cloned. (1 mark) 4. DLList *longestSublist(DLList *u). This function returns a doubly linked list that is the

longest sublist of u. The longest sublist v of a list u is defined as follows:

a. The greatest common divisor of all the elements (integers) of v is not 1 (we

consider positive divisors only).

b. No other sublist of u contains more elements than v.

Consider a list u = {2, -6, 8, 15, 11,23, 20}. The longest sublist v of u is {2, -6, 8, 20},

and the greatest common divisor of all the elements of v is 2.

Note that the longest sublist of a list may not be unique. Consider a list u = {2, 6, 4, 3,

9}. There are two longest sublists: v1={2, 6, 4} and v2={6, 3, 9}.

When analysing the time complexity of your algorithm, you may assume that the

maximum integer of the input list is a constant. Under this assumption, it takes

constant time O(1) to check if two integers are mutually prime (i.e., their only divisor

is 1). (3 marks) 5. DLList *setUnion(DLList *u, DLList *v). This function computes the union of the two

sets of integers that are stored in the doubly linked lists pointed by u and v,

respectively, and returns a pointer to the doubly linked list that stores the union. Each

element (int) of a set is stored in a node of the corresponding doubly linked list.

Given two sets A and B, the union of A and B is a set that contains all the distinct

element of A and B. For example, assuming that A = {2, 8, 5, 7} and B = {5, 9, 6, 7}, A

? B = {2, 8, 5, 7, 9, 6}. Note that in a set, all the integers are not necessarily sorted.

(2 marks) 6. DLList *setIntersection(DLList *u, DLList *v). This function computes the intersection

of the two sets of integers that are stored in the doubly linked lists pointed by u and

v, respectively, and returns a pointer to the doubly linked list that stores the

intersection. Each element (int) of a set is stored in a node of the corresponding

doubly linked list. (2 marks)

For simplicity, you may assume that all the elements of each input set are distinct

for both set union and set intersection. Therefore, you do not need to check if a set

contains duplicates.

Given two sets A and B, the intersection of A and B is a set that contains all the

elements of A that are also in B. For example, assuming that A = {2, 8, 5, 7} and B = {5,

9, 6, 7}, A ? B = {5, 7}.

7. void freeDLList(DLList *u). This function frees the space occupied by all the nodes of

the doubly linked list pointed by u. (1 marks)

Time complexity analysis: For each function, you need to analyze its time complexity in terms

of big-O notation and put your analysis as comments immediately before the code of the

function. You may assume that each built-in I/O function such as printf(), malloc() and free(),

takes O(1) time.

How to submit your code?

1. Go to the assignment one page

2. Click on Assignment Specfication

3. Click on Make Submission

4. Submit your MyDLList.c file that contains all the code.

Plagiarism

This is an individual assignment. Each student must work out his/her own solution without

help from other people. In particular, it is not permitted to exchange code or pseudocode.

You are not allowed to use code developed by persons other than yourself. All work

submitted for assessment must be entirely your own work. We regard unacknowledged

copying of material, in whole or part, as an extremely serious offence. For further

information, see the Course Information.