CSci 3501 Algorithms and Computability - Lab 6.
September 30. Due Wednesday, October 6 at 11:59pm
What to submit and when:
- All submissions are electronic: by e-mail to elenam at morris.umn.edu and CC to all lab
partners. Please do not delete your e-mail from "Sent mail" or your
mailbox until the end of the semester.
- When working on the lab, please comment your work so that it is
clear what contributions of each person are.
- At the end of the lab each group should send me the results of their
in-class work. Please indicate if this is your final submission.
- If your submission at the end of the lab time was not final,
please send me(CC to the lab partner(s)) a final copy before the due
time. Please use the subject "3501 Lab N", where N is the lab
number.
Lab assignment
Work in pairs
Lab overview and goals
The lab has two separate parts
The goal of part I of the lab is to practice with JFLAP (a tool for experimenting with
finite automata and other computability topics) and to design and test
DFAs.
The second part fo the lab revisits sorting methods and focuses on picking
the best approach for a particular sorting criteria.
Using JFLAP and naming your files
- Please save your automata files as .jff files and your data as
.txt files. Files names must be as follows: names
of those in the group followed by question name,
e.g.
SmithAdams3.jff
(where 3 refers to the question
number). This will help me in running test data
- To load test data from a file, go to
Input -> Multiple Runs
-> Load Inputs
- When adding multiple transitions between the same two states, add
them one by one. Typing "0, 1" in a label for an arrow will give you
a wrong result since the automaton will try to match this input
exactly, including the comma.
- When writing DFA, check that every state has a transition on every
symbol. JFLAP does not check it.
- Use
Convert -> Combine Automata
to copy one automaton into a file for another one.
- Do not use "convert to DFA" or "minimize DFA" options.
- Consult the JFLAP tutorial as
needed.
Lab tasks
Part 1 (10 points; 3 per each automaton and 1 for general set-up)
Unless specified otherwise, the
alphabet is the set of 0 and 1. Recall that zero is an even number.
Design and test the following finite automata:
- DFA to recognize the language of all strings that have at most
three zeros.
- DFA to recognize the language of all strings that have an even
number of zeros and an odd number of
ones.
- DFA to recognize the language of all strings that end at an even
number of zeros (i.e. the longest substring of 0s at the end of the
string is of even length).
Part 2 (to be graded later...)
Develop a sorting algorithm to sort words in a long text file (a few
thousand words) by the following criteria: by word length as a primary
criteria and alphabetically as a secondary one. This means that all
shorter words come before all longer words and within each group of
words of the same length the words are sorted alphabetically (more
precisely, according to compareTo method of String class).
Your goal is to develop an algorithm that sorts as fast as
possible. "Fast" here means direct timing of the program, not just the
Big-Theta approximation. You will get a text file to practice, but the
final test
will be done on a different file.
The assignment will run for two lab periods: one to get preliminary
competition results and the second one for the final competition.
Make sure to make your Eclipse workspace read-protected to
keep your "trade secrets". For the first competition, please send me a jar
file or a class file, not the source code.
Three groups that get the best time in the final run will get extra
credit.
Rules and requirements:
- You must use Java. While this may not be the best language choice
for efficiency purposes, this assignment is not about languages,
it's about algorithms. Thinking about implementation details is
important, however.
- The file may contain data that is not just letters, but most of it
is English words. Alphabetical comparison
must be done based on compareTo of String class. Note that
punctuation marks attached to words are considered a part of the
word (e.g.
when?
has the length of 5)
- Your program must read data from a file, store it internally as
an array, sort it, and then output it into a file. This link may be
helpful for file reading/writing: http://www.javapractices.com/topic/TopicAction.do?Id=42
- The program must take three command-line arguments: the name of
the input file, output file, and the number of loops. The last
argument will allow repeating the sorting multiple times to get more
accurate times if needed.
- The timing in the program is done similarly to lab 1
(using
System.currentTimeMillis()
). The timer starts
after you read the file and stops before you start writing out the
result. You might want to stop the current thead for a few
milliseconds after reading the file before you start the timer to
allow time to close the buffer reader.
- Your sorting starts by copying the given array into a new array
(in a loop) and then sorting that array in place. This is so that
you can repeat the sorting multiple times. Since the copying time
is the same for everyone, it will not affect the competition.
- Only the last copy of the sorted array should be copied to the
resulting file.
Use the file text1.txt for testing.
CSci 3501
course web site.