Download Solved Problems on Data Structures - Assignment 1 | CS 230 and more Assignments Data Structures and Algorithms in PDF only on Docsity!
CS230 Data Structures Handout # 8 Prof. Lyn Turbak January 30, 2007 Wellesley College
Problem Set 1
Due: 1:30pm Tuesday, February 13
Note: This assignments is due at the beginning of the first CS230 lab on Tuesday, February 13, regardless of which lab you happen to be in.
Overview: The purpose of this assignment is to give you practice writing some simple Java methods using Emacs and Java on the Linux workstations. Since learning a new programming environment takes time, it is strongly recommended that you (1) start early and (2) work with a partner. Allocate time over several days to work on the problems; it is very unwise to start the assignment only a day or two before it is due. Don’t hesitate to ask for help if you hit a roadblock.
Submission: Each team should turn in a single hardcopy submission packet for all problems by slipping it under Lyn’s office door by 1:30pm on the due date. The packet should include:
- a team header sheet (see the end of this assignment for the header sheet) indicating the time that you (and your partner, if you are working with one) spent on the parts of the assignment.
- your final version of DiceGame.java from Problem 1.
- a transcript demonstrating that your DiceGame program works as expected.
- your final version of Palindrome.java from Problem 2.
- a transcript demonstrating that your Palindrome program works as expected.
Each team should also submit a single softcopy (consisting of your entire final ps1 directory) to the drop directory ~cs230/drop/ps1/username, where username is the username of one of the team members (indicate which drop folder you used on your hardcopy header sheet). To do this, execute the following Linux commands in the team member’s account where the code is stored:
cd /students/username/cs cp -R ps1 ~cs230/drop/ps1/username/
Problem 0: Getting Started
a. : Puma Account If you do not already have a Puma account (from taking CS111), you should begin this assignment by requesting a Puma account by following the directions on Handout #3. If you do have an account but have forgotten your password, contact Lyn or Scott Anderson to reset it.
b. : Linux Once you have your Puma account, you should log in to a Linux workstation and learn some simple Linux commands, as described in Handouts #3 and #4.
c. : Emacs Next you should learn how to use Emacs. See the information in Handouts #3 and #5 on using Emacs. Learning to execute all cursor-motion and editing commands via keystrokes (rather than via mouse and menus) is an important skill that will save you lots of time over the semester. It will also make it easier for you to work remotely via ssh. A good way to begin learning the keystroke commands is taking the online interactive Emacs tutorial (see Handout #3 for how to do this).
d. : CVS To do the rest of the problems on this assignment, you will need to use several files that are in the CVS-controlled CS230 repository. Follow the directions in Handout #7 for how to install your local CVS filesystem. You only need to install it once. Once you have installed your local CVS filesystem, you can access all CVS-controlled files by executing the following in a Linux shell: cd ~/cs cvs update -d
Indeed, every time you log in to a Linux machine to work on a CS230 assignment, you should execute the above commands to ensure that you have the most up-to-date versions of the problem set materials. On this assignment, executing the above commands will create the local directory ~/cs230/ps containing the following three files:
- DiceGame.java: This file contains a Java skeleton for the DicePoker game for Problem 1.
- sentences.txt: This file contains some sentences for testing the palindrome checker in Problem 2.
- big.txt: This file contains a single very long palindromic line for testing the palindrome checker in Problem 2.
/** Simulates a Dice Poker game played between the computer and user.
- This class definition contains a main() method that assumes
- that the user enters a name and an optional number of rounds
- in the command line. For example:
- java PlayDice Wendy (plays 5 rounds by default);
- java PlayDice Dave 10 (plays 10 rounds)
- @author Takis Metaxas provided the original skeleton
- @author [01/30/07] Lyn Turbak made several changes to the skeleton
- @author Your name here
- @version %I%, %G% */ public class DiceGame {
/* Start the homework by reading this main method. / /* Simulates a Dice Poker game played between the computer and user.
- args[0] should be the name of the user;
- args[1] is an optional number of rounds (the rounds will be 5 by
- (default if not explicitly specified). */ public static void main (String args[]) {
// If invocation is malformed, do not let user play if ((args.length == 0) || (args.length > 2)) { System.out.println("Usage: java DiceGame []"); System.exit(0); }
try { String name = args[0]; int rounds = (args.length == 2)? (Integer.parseInt(args[1])) : 5; // 5 is the default number of rounds if not supplied by user
playDiceGame(name, rounds); } catch (NumberFormatException ex) { // thrown if args[1] doesn’t specify an integer System.out.println("Sorry, "" + args[1] + "" is not an integer number of rounds."); System.out.println("Usage: java DiceGame []"); }
}
Figure 1: Code skeleton for DiceGame.java, part 1
/** Simulates the playing of numRounds of the Dice Poker game between
- HAL and player name, and prints the winner at the end
- @param name the player’s name
- @param numRounds the number of rounds to play */ public static void playDiceGame (String name, int numRounds) {
System.out.println("Hello " + name + "."); System.out.println("I’m completely operational and all my circuits are functioning perfectly."); System.out.println("Would you like to play a game of Dice Poker? I play very well.");
// declare variables for storing the score of all the rounds int cwin=0, pwin=0; // round wins of the computer (0) and the player (1)
// for each round of the game: int rounds = 1; do{ System.out.println("*** ROUND " + rounds); // play the round, determine the winner of the round int winner = playOneRound(); if(winner == 0) cwin++; if(winner == 1) pwin++; } while(rounds++ < numRounds);
// After all rounds played, determine the final winner of the game and print the results if(pwin>cwin) System.out.print("The game was won by "+ name + " with a score of "
- pwin + " to " + cwin); else if(cwin>pwin) System.out.print("The game was won by the HAL with a score of "
- cwin + " to " + pwin); else System.out.print("The game was tied with a score of " + cwin + " to " + pwin);
System.out.println(" in " + numRounds + " rounds."); }
/** Plays one round of the game: First the computer’s turn,
- then the player’s turn
- @return 0 if computer wins the round, 1 if player wins, 2 if a tie */ public static int playOneRound() {
// *** FLESH OUT THIS METHOD (and replace the following stub): return 2;
}
/** Simulates the rolling of five dice by throwing one dice 5 times.
- @return a new five-slot array filled with random integers between 1 and 6. */ public static int[] throw5Dice() { int[] diceArray = new int[5]; for (int i = 0; i < 5; i++) diceArray[i] = (int)(Math.random() * 6) + 1; return diceArray; }
Figure 2: Code skeleton for DiceGame.java, part 2
To understand the skeleton we have given you, you should start by reading the main() method, and then read the rest of the program as needed. The program is complete except for three methods. Your task is to complete the definitions of the following three methods:
- public static int[] accumulateValues(int[] input) Given an input array input containing five dice values, this method should determine how many of each of the possible six dice values appear in input, and return this information in the output array, which we will call accumResult. For simplicity, assume that accumResult is an array of 7 integers such that accumResult[0] is necessarily 0 and accumResult[i ] contains the number of times i appears in input. That is, accumResult[1] should contain the number of 1s that appear in input, accumResult[2] should contain the number of 2s, and so on. E.g., for the input array {1,4,4,5,1}, accumResult should be {0,2,0,0,2,1,0}. Think carefully about how to implement this method compactly – its definition can be very concise. The purpose of defining this method is to facilitate the implementation of the next method, getRank().
- public static int getRank (int[] input) Given an input array input containing five dice values, this method should return the rank of the combination of values (an integer between 0 and 6, as described earlier). In the program skeleton, the body of the getRank() method already contains a statement that declares an array diceResults that stores how many of each dice value are contained in input. There are many strategies for implementing the rest of this method — think carefully about different options before writing any code.
- public static int playOneRound() This method simulates one round of the game by first simulating the computer’s turn (throws the 5 dice and getting its rank), then simulating the player’s turn, and then determining the winner. It returns an integer that signifies the winner: 0 if the computer wins, 1 if the user wins, and 2 if there is a tie.
An important piece of advice that we will reinforce throughout the semester is to construct your implementation incrementally — build and test one method at a time! Begin by completing the definition of accumulateValues() and adding test code to the playOneRound() method to test your code. Next complete the definition and testing of the getRank() method. And so on. Larger methods can also be created and tested in small pieces. As you build your implementation, also keep in mind the comments about programming style at the beginning of this handout. In the comments at the beginning of the file, be sure to add your name and the date of completion of your code.
The Output Fig. 4 presents two sample runs of the complete DiceGame program. Note that five rounds are played by default if the number of rounds is not explicitly specified.
Notes on Programming Style Programs that you compose for your CS230 assignments and labs will be evaluated not only on whether your programs work correctly, but also on programming style. This includes the use of informative names, good comments, easily readable formatting, and a good balance between compactness and clarity (e.g., do not define unnecessary variables or write multiple statements to perform a task that can be expressed clearly in a single statement.) Follow the guidelines in Takis Metaxas’s On Programming Style, which is available on the CS230 Documentation page. In large software development projects involving a team of programmers, it is customary to include comments at the beginning of each code file that include information such as the file name,
[fturbak@puma ps1] java DiceGame Dave 7 Hello Dave. I’m completely operational and all my circuits are functioning perfectly. Would you like to play a game of Dice Poker? I play very well. *** ROUND 1 HAL: 3 5 4 4 5 : Two Pair You: 3 3 6 1 2 : One Pair *** ROUND 2 HAL: 2 1 1 1 5 : Three of a Kind You: 4 6 1 3 6 : One Pair *** ROUND 3 HAL: 4 3 4 5 2 : One Pair You: 1 2 5 1 3 : One Pair *** ROUND 4 HAL: 3 6 1 3 5 : One Pair You: 6 2 6 4 2 : Two Pair *** ROUND 5 HAL: 5 5 2 6 3 : One Pair You: 2 5 2 6 5 : Two Pair *** ROUND 6 HAL: 5 3 6 2 2 : One Pair You: 2 2 6 2 2 : Four of a Kind *** ROUND 7 HAL: 4 3 5 5 2 : One Pair You: 5 3 5 1 1 : Two Pair The game was won by Dave with a score of 4 to 2 in 7 rounds.
[fturbak@puma ps1] java DiceGame Lyn Hello Lyn. I’m completely operational and all my circuits are functioning perfectly. Would you like to play a game of Dice Poker? I play very well. *** ROUND 1 HAL: 6 5 5 2 3 : One Pair You: 6 1 2 3 1 : One Pair *** ROUND 2 HAL: 4 3 3 1 6 : One Pair You: 2 3 3 3 1 : Three of a Kind *** ROUND 3 HAL: 1 2 5 1 3 : One Pair You: 4 4 4 5 4 : Four of a Kind *** ROUND 4 HAL: 6 6 6 3 4 : Three of a Kind You: 2 1 2 6 4 : One Pair *** ROUND 5 HAL: 3 6 3 2 4 : One Pair You: 1 2 3 1 5 : One Pair The game was won by Lyn with a score of 2 to 1 in 5 rounds.\end{scode}%
Figure 4: Sample output from two runs of the DiceGame program.
[fturbak@puma ps1] java Palindrome "Golf? No sir -- prefer prison flog!" bash: !": event not found [fturbak@puma ps1] java Palindrome "Golf? No sir -- prefer prison flog!" "Golf? No sir -- prefer prison flog!" is a palindrome
- File Mode In file mode, which is invoked via java Palindrome -file , your palindrome checker should check each line in the file named . Each line in the file should be echoed to the console, separated by a blank line. Lines that are palindromes should be prefixed with the characters *:, while lines that are not palindromes should be prefixed with o:. For example, suppose the file test.txt contains the following lines: Madam, I’m adam. Mister, I’m adam. Madam, I’m eve. No lemon, no melon. No lemons, no melons. Then here is a sample use of the Palindrome program in file mode: [fturbak@puma ps1] java Palindrome -file test.txt *:Madam, I’m adam.
o:Mister, I’m adam.
o:Madam, I’m eve.
*:No lemon, no melon.
o:No lemons, no melons.
If there is no file with the given filename, the program should indicate this fact, as shown below: [fturbak@puma ps1] java Palindrome -file foo.txt There is no file named foo.txt
Any attempt to use the Palindrome program that does not match one of the above two modes should display a message that suggests the correct usage:
[fturbak@puma ps1] java Palindrome usage: java Palindrome OR java Palindrome -file [fturbak@puma ps1] java Palindrome foo bar usage: java Palindrome OR java Palindrome -file [fturbak@puma ps1] java Palindrome foo bar baz usage: java Palindrome OR java Palindrome -file There are many ways to implement this program. Choose a palindrome-checking strategy that is easy to understand. Make liberal use of auxiliary methods to clarify your program. Your goal is not only to develop a working program, but to create a program whose structure is exceptionally clear. In your hardcopy, you should submit your final Palindrome.java program, along with a tran- script demonstrating that your program works as specified. To test file mode, you must try your program on the files ~/cs230/ps1/sentences.txt and ~/cs230/ps1/big.txt (the latter file con- tains a very long palindrome). However, to save paper, do not include big.txt in your transcript. Also submit a softcopy as specified on the first page of this assignment.
Problem Set Header Page Please make this the first page of your hardcopy submission.
CS230 Problem Set 1
Due 1:30pm Tuesday February 13
Names of Team Members:
Date & Time Submitted:
Collaborators (anyone you or your team collaborated with):
By signing below, I/we attest that I/we have followed the collaboration policy
as specified in the Course Information handout.
Signature(s):
In the Time column, please estimate the time you or your team spent on the parts of this problem set. Team members should be working closely together, so it will be assumed that the time reported is the time for each team member. Please try to be as accurate as possible; this information will help me design future problem sets. I will fill out the Score column when grading your problem set.
Part Time Score
General Reading
Problem 1 [50]
Problem 2 [50]
Total
