CSE 2320 - Assignments - Assignment 4

Submit to Blackboard before the deadline. You will be able to revise your answers until the deadline with no penalty.

IMPORTANT: By submitting your answers, you are certifying that these answers have been exclusively your own work. All students enrolled in this course are expected to adhere to the UT Arlington Honor Code:

I pledge, on my honor, to uphold UT Arlington's tradition of academic integrity, a tradition that values hard work and honest effort in the pursuit of academic excellence. I promise that I will submit only work that I personally create or contribute to group collaborations, and I will appropriately reference any work from other sources. I will follow the highest standards of integrity and uphold the spirit of the Honor Code.

Task 1 (40 pts.)

Write a program (in C, C++, Java, or Python) that can evaluate infix expressions under the following assumptions:

They are fully parenthesized.
They only use operators and positive integers. No negative integers, decimal parts, or variables.
Every operator has two operands, no more, no fewer.

If you are using C, C++, or Java, your program should take one command line argument. For example, in C, if your compiled program is called a.out, you should call the program as follows:

a.out filename

Commandline argument filename should be the name of a file containing expressions to be evaluated, such as in1.txt. There should be one expression per line. To help you get started, we provide the following resources:

File infix_main.c contains most of the code that you need for the solution. Feel free to use this code, and add the code that is needed to convert this code into a complete solution for this task. If you use this file, you just need to implement these two functions, which have been left undefined:
- int evaluatePostfix(list tokens)
File infix_main.c should be compiled together with these files:
The header files associated with those three C files (available at this directory) should be placed in the same directory as the source code. In the opinion of the instructor, using the code in infix_main.c is probably the easiest way to solve this task (my solution is 70 additional lines of code added to infix_main.c, and this includes several empty lines, and 45 real lines of code, excluding the empty lines). Still, if you choose so, you are free to write your own code from scratch in C, C++, Java, or Python.
File in1.txt is an example input file.

As an example, if you run your solution using file in1.txt as the input file, you should get the following output:

--------------------------------
processing: (5 * (((9 + 8) *  (4 * 6)) + 7))

infix tokens:
( 5 * ( ( ( 9 + 8 ) * ( 4 * 6 ) ) + 7 ) ) 

postfix tokens:
5 9 8 + 4 6 * * 7 + * 

result: 2075
--------------------------------
processing: 

--------------------------------
processing: ((17 * (12-5)) + (9 / 3))

infix tokens:
( ( 17 * ( 12 - 5 ) ) + ( 9 / 3 ) ) 

postfix tokens:
17 12 5 - * 9 3 / + 

result: 122

Task 2 (10 pts.)

(This is Problem 3.56 from the textbook).

Write a function that takes a string as an argument and prints out a table giving, for each character that occurs in the string, the character and its frequency of occurrence (the number of times that the character occurs).

Task 3 (10 pts.)

(This is Problem 3.57 from the textbook).

Write a function that takes a string as an argument, and that checks whether that string is a palindrome (reads the same backward or forward), ignoring blanks. For example, your program should report success for the string "if i had a hifi".

Task 4 (15 pts.)

(This is Problem 3.60 from the textbook).

Write a function that takes in a string as an argument, and that replaces substrings of more than one blank in a given string by exactly one blank. Note that this function should modify the contents of its input argument, as opposed to returning a new string that has the required modifications.

Task 5 (15 pts.)

(This is Problem 3.74 from the textbook).

Write a function countEdges(int ** adjacencies, int A, int B, int V) that takes as input the adjacency matrix of graph, two integers specifying vertices A and B, and an integer V specifying the number of vertices in the graph. The function should return the number of vertices C with the property that there is an edge from A to C and from C to B. You can assume that the graph is undirected.

Task 6 (10 pts.)

(This is Problem 4.7 from the textbook).

Using the conventions of Textbook Exercise 4.6, give a way to insert asterisks in the sequence E A S Y so that the sequence of values returned by the pop operations is:

(i) E A S Y
(ii) Y S A E
(iii) A S Y E
(iv) A Y E S

Or, where applicable, prove that no such sequence exists.

How to submit

The assignment should be submitted via Blackboard. Submit a ZIPPED directory called assignment.zip. No other forms of compression are accepted, contact the instructor or TA if you do not know how to produce .zip files. The zipped directory should contain the following documents:

answers.xxx. A PDF or Word file containing your solutions for each task. Include your name and UTA ID number at the top of this document. Even though most tasks are programming tasks, it is still useful for grading to have a document where you just show the code you wrote to solve a task.
infix_main.c Your modified infix_main.c that includes the changes you made to solve Task 1. If you needed to modify other files, include those as well.

As stated on the course syllabus, programs must be in C or Java, and must run on omega.uta.edu. If you want to do this in any language other than C, you have to re-implement in that language all the code that is currently implemented at lists.c, stacks_lists.c, and tokens.c. If you want to use another language or platform, you must obtain prior approval via e-mail by the instructor.

IMPORTANT: Pay close attention to all specifications on this page, including file names and submission format. Even in cases where your answers are correct, points will be taken off liberally for non-compliance with the instructions given on this page (such as wrong file names, wrong compression format for the submitted code, and so on). The reason is that non-compliance with the instructions makes the grading process significantly (and unnecessarily) more time consuming. Contact the instructor or TA if you have any questions.

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