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  • Why can't my main class see the array in my calender class

    - by Rocky Celltick Eadie
    This is a homework problem. I'm already 5 days late and can't figure out what I'm doing wrong.. this is my 1st semester in Java and my first post on this site Here is the assignment.. Create a class called Calendar. The class should contain a variable called events that is a String array. The array should be created to hold 5 elements. Use a constant value to specify the array size. Do not hard code the array size. Initialize the array in the class constructor so that each element contains the string “ – No event planned – “. The class should contain a method called CreateEvent. This method should accept a String argument that contains a one-word user event and an integer argument that represents the day of the week. Monday should be represented by the number 1 and Friday should be represented by the number 5. Populate the events array with the event info passed into the method. Although the user will input one-word events, each event string should prepend the following string to each event: event_dayAppoinment: (where event_day is the day of the week) For example, if the user enters 1 and “doctor” , the first array element should read: Monday Appointment: doctor If the user enters 2 and “PTA” , the second array element should read: Tuesday Appointment: PTA Write a driver program (in a separate class) that creates and calls your Calendar class. Then use a loop to gather user input. Ask for the day (as an integer) and then ask for the event (as a one word string). Pass the integer and string to the Calendar object’s CreateEvent method. The user should be able enter 0 – 5 events. If the user enters -1, the loop should exit and your application should print out all the events in a tabular format. Your program should not allow the user to enter invalid values for the day of the week. Any input other than 1 – 5 or -1 for the day of the week would be considered invalid. Notes: When obtaining an integer from the user, you will need to use the nextInt() method on your Scanner object. When obtaining a string from a user, you will need to use the next() method on your Scanner object. Here is my code so far.. //DRIVER CLASS /** * * @author Rocky */ //imports scanner import java.util.Scanner; //begin class driver public class driver { /** * @paramargs the command line arguments */ //begin main method public static void main(String[] args) { //initiates scanner Scanner userInput = new Scanner (System.in); //declare variables int dayOfWeek; String userEvent; //creates object for calender class calendercalenderObject = new calender(); //user prompt System.out.println("Enter day of week for your event in the following format:"); System.out.println("Enter 1 for Monday"); System.out.println("Enter 2 for Tuesday"); System.out.println("Enter 3 for Wednsday"); System.out.println("Enter 4 for Thursday"); System.out.println("Enter 5 for Friday"); System.out.println("Enter -1 to quit"); //collect user input dayOfWeek = userInput.nextInt(); //user prompt System.out.println("Please type in the name of your event"); //collect user input userEvent = userInput.next(); //begin while loop while (dayOfWeek != -1) { //test for valid day of week if ((dayOfWeek>=1) && (dayOfWeek<=5)){ //calls createEvent method in calender class and passes 2 variables calenderObject.createEvent(userEvent,dayOfWeek); } else { //error message System.out.println("You have entered an invalid number"); //user prompts System.out.println("Press -1 to quit or enter another day"); System.out.println("Enter 1 for Monday"); System.out.println("Enter 2 for Tuesday"); System.out.println("Enter 3 for Wednsday"); System.out.println("Enter 4 for Thursday"); System.out.println("Enter 5 for Friday"); System.out.println("Enter -1 to quit"); //collect user input dayOfWeek = userInput.nextInt(); //end data validity test } //end while loop } //prints array to screen int i=0; for (i=0;i<events.length;i++){ System.out.println(events[i]); } //end main method } } /** * * @author Rocky */ //imports scanner import java.util.Scanner; //begin calender class public class calender { //creates events array String[] events = new String[5]; //begin calender class constructor public calender() { //Initializes array String[] events = {"-No event planned-","-No event planned-","-No event planned-","-No event planned-","-No event planned-"}; //end calender class constructor } //begin createEvent method public String[] createEvent (String userEvent, int dayOfWeek){ //Start switch test switch (dayOfWeek){ case 1: events[0] = ("Monday Appoinment:") + userEvent; break; case 2: events[1] = ("Tuesday Appoinment:") + userEvent; break; case 3: events[2] = ("WednsdayAppoinment:") + userEvent; break; case 4: events[3] = ("Thursday Appoinment:") + userEvent; break; case 5: events[4] = ("Friday Appoinment:") + userEvent; break; default: break; //End switch test } //returns events array return events; //end create event method } //end calender class }

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  • I asked this yesterday, after the input given I'm still having trouble implementing..

    - by Josh
    I'm not sure how to fix this or what I did wrong, but whenever I enter in a value it just closes out the run prompt. So, seems I do have a problem somewhere in my coding. Whenever I run the program and input a variable, it always returns the same answer.."The content at location 76 is 0." On that note, someone told me that "I don't know, but I suspect that Program A incorrectly has a fixed address being branched to on instructions 10 and 11." - mctylr but I'm not sure how to fix that.. I'm trying to figure out how to incorporate this idea from R Samuel Klatchko.. I'm still not sure what I'm missing but I can't get it to work.. const int OP_LOAD = 3; const int OP_STORE = 4; const int OP_ADD = 5; ... const int OP_LOCATION_MULTIPLIER = 100; mem[0] = OP_LOAD * OP_LOCATION_MULTIPLIER + ...; mem[1] = OP_ADD * OP_LOCATION_MULTIPLIER + ...; operand = memory[ j ] % OP_LOCATION_MULTIPLIER; operation = memory[ j ] / OP_LOCATION_MULTIPLIER; I'm new to programming, I'm not the best, so I'm going for simplicity. Also this is an SML program. Anyway, this IS a homework assignment and I'm wanting a good grade on this. So I was looking for input and making sure this program will do what I'm hoping they are looking for. Anyway, here are the instructions: Write SML (Simpletron Machine language) programs to accomplish each of the following task: A) Use a sentinel-controlled loop to read positive number s and compute and print their sum. Terminate input when a neg number is entered. B) Use a counter-controlled loop to read seven numbers, some positive and some negative, and compute + print the avg. C) Read a series of numbers, and determine and print the largest number. The first number read indicates how many numbers should be processed. Without further a due, here is my program. All together. int main() { const int READ = 10; const int WRITE = 11; const int LOAD = 20; const int STORE = 21; const int ADD = 30; const int SUBTRACT = 31; const int DIVIDE = 32; const int MULTIPLY = 33; const int BRANCH = 40; const int BRANCHNEG = 41; const int BRANCHZERO = 41; const int HALT = 43; int mem[100] = {0}; //Making it 100, since simpletron contains a 100 word mem. int operation; //taking the rest of these variables straight out of the book seeing as how they were italisized. int operand; int accum = 0; // the special register is starting at 0 int j; // This is for part a, it will take in positive variables in a sent-controlled loop and compute + print their sum. Variables from example in text. memory [0] = 1010; memory [01] = 2009; memory [02] = 3008; memory [03] = 2109; memory [04] = 1109; memory [05] = 4300; memory [06] = 1009; j = 0; //Makes the variable j start at 0. while ( true ) { operand = memory[ j ]%100; // Finds the op codes from the limit on the memory (100) operation = memory[ j ]/100; //using a switch loop to set up the loops for the cases switch ( operation ){ case 10: //reads a variable into a word from loc. Enter in -1 to exit cout <<"\n Input a positive variable: "; cin >> memory[ operand ]; break; case 11: // takes a word from location cout << "\n\nThe content at location " << operand << "is " << memory[operand]; break; case 20:// loads accum = memory[ operand ]; break; case 21: //stores memory[ operand ] = accum; break; case 30: //adds accum += mem[operand]; break; case 31: // subtracts accum-= memory[ operand ]; break; case 32: //divides accum /=(memory[ operand ]); break; case 33: // multiplies accum*= memory [ operand ]; break; case 40: // Branches to location j = -1; break; case 41: //branches if acc. is < 0 if (accum < 0) j = 5; break; case 42: //branches if acc = 0 if (accum == 0) j = 5; break; case 43: // Program ends exit(0); break; } j++; } return 0; }

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  • C++ Sentinel/Count Controlled Loop beginning programming

    - by Bryan Hendricks
    Hello all this is my first post. I'm working on a homework assignment with the following parameters. Piecework Workers are paid by the piece. Often worker who produce a greater quantity of output are paid at a higher rate. 1 - 199 pieces completed $0.50 each 200 - 399 $0.55 each (for all pieces) 400 - 599 $0.60 each 600 or more $0.65 each Input: For each worker, input the name and number of pieces completed. Name Pieces Johnny Begood 265 Sally Great 650 Sam Klutz 177 Pete Precise 400 Fannie Fantastic 399 Morrie Mellow 200 Output: Print an appropriate title and column headings. There should be one detail line for each worker, which shows the name, number of pieces, and the amount earned. Compute and print totals of the number of pieces and the dollar amount earned. Processing: For each person, compute the pay earned by multiplying the number of pieces by the appropriate price. Accumulate the total number of pieces and the total dollar amount paid. Sample Program Output: Piecework Weekly Report Name Pieces Pay Johnny Begood 265 145.75 Sally Great 650 422.50 Sam Klutz 177 88.5 Pete Precise 400 240.00 Fannie Fantastic 399 219.45 Morrie Mellow 200 110.00 Totals 2091 1226.20 You are required to code, compile, link, and run a sentinel-controlled loop program that transforms the input to the output specifications as shown in the above attachment. The input items should be entered into a text file named piecework1.dat and the ouput file stored in piecework1.out . The program filename is piecework1.cpp. Copies of these three files should be e-mailed to me in their original form. Read the name using a single variable as opposed to two different variables. To accomplish this, you must use the getline(stream, variable) function as discussed in class, except that you will replace the cin with your textfile stream variable name. Do not forget to code the compiler directive #include < string at the top of your program to acknowledge the utilization of the string variable, name . Your nested if-else statement, accumulators, count-controlled loop, should be properly designed to process the data correctly. The code below will run, but does not produce any output. I think it needs something around line 57 like a count control to stop the loop. something like (and this is just an example....which is why it is not in the code.) count = 1; while (count <=4) Can someone review the code and tell me what kind of count I need to introduce, and if there are any other changes that need to be made. Thanks. [code] //COS 502-90 //November 2, 2012 //This program uses a sentinel-controlled loop that transforms input to output. #include <iostream> #include <fstream> #include <iomanip> //output formatting #include <string> //string variables using namespace std; int main() { double pieces; //number of pieces made double rate; //amout paid per amount produced double pay; //amount earned string name; //name of worker ifstream inFile; ofstream outFile; //***********input statements**************************** inFile.open("Piecework1.txt"); //opens the input text file outFile.open("piecework1.out"); //opens the output text file outFile << setprecision(2) << showpoint; outFile << name << setw(6) << "Pieces" << setw(12) << "Pay" << endl; outFile << "_____" << setw(6) << "_____" << setw(12) << "_____" << endl; getline(inFile, name, '*'); //priming read inFile >> pieces >> pay >> rate; // ,, while (name != "End of File") //while condition test { //begining of loop pay = pieces * rate; getline(inFile, name, '*'); //get next name inFile >> pieces; //get next pieces } //end of loop inFile.close(); outFile.close(); return 0; }[/code]

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  • Vector of Object Pointers, general help and confusion

    - by Staypuft
    Have a homework assignment in which I'm supposed to create a vector of pointers to objects Later on down the load, I'll be using inheritance/polymorphism to extend the class to include fees for two-day delivery, next day air, etc. However, that is not my concern right now. The final goal of the current program is to just print out every object's content in the vector (name & address) and find it's shipping cost (weight*cost). My Trouble is not with the logic, I'm just confused on few points related to objects/pointers/vectors in general. But first my code. I basically cut out everything that does not mater right now, int main, will have user input, but right now I hard-coded two examples. #include <iostream> #include <string> #include <vector> using namespace std; class Package { public: Package(); //default constructor Package(string d_name, string d_add, string d_zip, string d_city, string d_state, double c, double w); double calculateCost(double, double); void Print(); ~Package(); private: string dest_name; string dest_address; string dest_zip; string dest_city; string dest_state; double weight; double cost; }; Package::Package() { cout<<"Constucting Package Object with default values: "<<endl; string dest_name=""; string dest_address=""; string dest_zip=""; string dest_city=""; string dest_state=""; double weight=0; double cost=0; } Package::Package(string d_name, string d_add, string d_zip, string d_city, string d_state, string r_name, string r_add, string r_zip, string r_city, string r_state, double w, double c){ cout<<"Constucting Package Object with user defined values: "<<endl; string dest_name=d_name; string dest_address=d_add; string dest_zip=d_zip; string dest_city=d_city; string dest_state=d_state; double weight=w; double cost=c; } Package::~Package() { cout<<"Deconstructing Package Object!"<<endl; delete Package; } double Package::calculateCost(double x, double y){ return x+y; } int main(){ double cost=0; vector<Package*> shipment; cout<<"Enter Shipping Cost: "<<endl; cin>>cost; shipment.push_back(new Package("tom r","123 thunder road", "90210", "Red Bank", "NJ", cost, 10.5)); shipment.push_back(new Package ("Harry Potter","10 Madison Avenue", "55555", "New York", "NY", cost, 32.3)); return 0; } So my questions are: I'm told I have to use a vector of Object Pointers, not Objects. Why? My assignment calls for it specifically, but I'm also told it won't work otherwise. Where should I be creating this vector? Should it be part of my Package Class? How do I go about adding objects into it then? Do I need a copy constructor? Why? What's the proper way to deconstruct my vector of object pointers? Any help would be appreciated. I've searched for a lot of related articles on here and I realize that my program will have memory leaks. Using one of the specialized ptrs from boost:: will not be available for me to use. Right now, I'm more concerned with getting the foundation of my program built. That way I can actually get down to the functionality I need to create. Thanks.

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  • user input question

    - by jdbeverly87
    My program checks to test if a word or phrase is a palindrome (reads the same both backward and forward, ex "racecar"). The issue I'm having is after someone enters in "racecar" getting it to actually test. In the below code, I marked where if I type in "racecar" and run, Java returns the correct answer so I know I'm right there. But what am I missing as far as entering it into the console. I think my code is ok, but maybe I have something missing or in the wrong spot? Not really looking for a new answer unless I'm missing something, but if possible perhaps a pro at this moving my code to the correct area bc I'm stuck! `import java.util.*; public class Palindrome { public static void main(String[] args) { String myInput; Scanner in = new Scanner(System.in); System.out.println("Enter a word or phrase: "); **//this asks user for input but doesn't check for whether or not it is a palindrome** myInput = in.nextLine(); in.close(); System.out.println("You entered: " + myInput); } { String s="racecar"; **//I can type a word here and it works but I need** int i; **//I need it to work where I ask for the input** int n=s.length(); String str=""; for(i=n-1;i>=0;i--) str=str+s.charAt(i); if(str.equals(s)) System.out.println(s+ " is a palindrome"); else System.out.println(s+ " is not a palindrome"); } }` I'm new at programming so I'm hoping what I got is ok. I know the palindrome test works I'm just needing helping having it test thru where I'm entering it into the console. Thanks

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  • Computer science final year project ideas

    - by roul
    I'm a Computer Science undergraduate student in UK and should be deciding the subject of my final year project soon. The school is pretty flexible with the subject... "The topic can be any area of the subject which is of mutual interest to both the student and supervisor. Topics can range from purely theoretical studies to practical work building a system for some third party, although most projects aim to provide a balance between the theoretical and practical aspects of the subject." ...so I'm a bit lost since I want to do something in software engineering but have no idea what (subject) or with what (languages)! :) a) Languages: I've had experience with Java, C# and ASP.NET mostly but I would definitely be interested in learning new languages/frameworks. I'm kind of drawn by the idea of dynamic languages at the moment so IronPython seems likely. b) Subject: Anything that will keep me interested through the year and will give me the opportunity to learn a lot of stuff. Maybe something that has to do with music, or a fancy website, or a website about music :P anything really. Open to any thoughts/ideas, geeky or cool! Edit: Professors do usually supervise projects in their research areas but I currently have the choice to approach any of them according to my interest - whatever that is.

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  • java recursion on array

    - by user69514
    I have to create a program that finds all the possible ways of filling a board of size 3xN You place a domino which takes up 2 spaces to completely fill the board. So far, this is my thought process on how it should be done based on what the teacher has said as well as my own thoughts. Get input and check if its even or odd If it's odd, the board can't be filled all the way and the program ends If it's even, place a domino horizontally in the top right corner of the board Test if you can place a domino vertically in that spot. Repeat those two steps as many times as possible. The problem is I don't know how to code it to the point where you can remember the placements of each domino. I can get it to where it fills the board completely once and maybe twice, but nothing past that. I also know that I'm supposed to use recursion to figure this out fwiw. Here is the code I started on so far. There is also a main method and I have the initial even/odd check working fine. This is the part I have no idea on. public void recurDomino(int row, int column) { if (Board[2][x - 1] != false) { } else if(Board[1][x-1]!=false) { } else { for (int n=0; n < x - 1; n++) { Board[row][column] = true; Board[row][column+1] = true; column++; counter++; } recurDomino(1, 0); recurDomino(2, 0); } } Thank you for any help you guys can give me.

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  • Exam Questions that use .Demand or .LinkDemand COULD NOT BE ANY MORE CONFUSING OR AMBIGIOUS ????

    - by IbrarMumtaz
    I am 110% sure this is WRONG !!!! Q.12) You develop a library, and want to ensure that the functions in the library cannot be either directly or indirectly invoked by applications that are not running on the local intranet. What attribute would you add to each method? A. [UrlIdentityPermission(SecurityAction.RequestRefuse, Url="http://myintranet")] B. [UrlIdentityPermission(SecurityAction.LinkDemand, Url="http://myintranet")] (correct answer) C. [UrlIdentityPermission(SecurityAction.Demand, Url="http://myintranet")] D. [UrlIdentityPermission(SecurityAction.Assert, Url="http://myintranet")] Explanation Link-Demand should be used as it ensures that all callers in the call stack have the necessary permission. In this case it ensures that all callers in the call stack are on the local intranet. There is an indentical question on Transencer so I already had a clue what was goin but Transcender was much more informative that this drivel as it mentioned class level and not assembly level. It also mentioned that some callers maybe coming externally from the company intranet via authroised and authenticated credentials. With information is easy to see why .Demand on would be wong option to go for? So Transcender was right .... so I thgt fine, that makes sense. With think information still fresh in my brain I had a good idea was was going on in the question. To my surprise .Demand was wrong agin !!!! WHAT? I am really starting to hate this setting now? I cannot be any more p*ssed right now!!! :@ Thanks For Reading, Ibrar

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  • Designing bayesian networks

    - by devoured elysium
    I have a basic question about Bayesian networks. Let's assume we have an engine, that with 1/3 probability can stop working. I'll call this variable ENGINE. If it stops working, then your car doesn't work. If the engine is working, then your car will work 99% of the time. I'll call this one CAR. Now, if your car is old(OLD), instead of not working 1/3 of the time, your engine will stop working 1/2 of the time. I'm being asked to first design the network and then assign all the conditional probabilities associated with the table. I'd say the diagram of this network would be something like OLD -> ENGINE -> CAR Now, for the conditional probabilities tables I did the following: OLD |ENGINE ------------ True | 0.50 False | 0.33 and ENGINE|CAR ------------ True | 0.99 False | 0.00 Now, I am having trouble about how to define the probabilities of OLD. In my point of view, old is not something that has a CAUSE relationship with ENGINE, I'd say it is more a characteristic of it. Maybe there is a different way to express this in the diagram? If the diagram is indeed correct, how would I go to make the tables? Thanks

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  • Choosing design method for ladder-like word game.

    - by owca
    I'm trying to build a simple application, with the finished program looking like this : I will also have to implement two different GUI layouts for this. Now I'm trying to figure out the best method to perform this task. My professor told me to introduce Element class with 4 states : - empty - invisible (used in GridLayout) - first letter - other letter I've thought about following solutions (by List I mean any sort of Collection) : 1. Element is a single letter, and each line is Element[]. Game class will be array of arrays Element[]. I guess that's the dumbest way, and the validation might be troublesome. 2. Like previously but Line is a List of Element. Game is an array of Lines. 3. Like previously but Game is a List of Lines. Which one should I choose ? Or maybe do you have better ideas ? What collection would be best if to use one ?

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  • Unresolved external symbol error in c++

    - by Crystal
    I am trying to do a simple hw problem involving namespace, static data members and functions. I am getting an unresolved external symbol error Error 1 error LNK2001: unresolved external symbol "private: static double JWong::SavingsAccount::annualInterestRate" (?annualInterestRate@SavingsAccount@JWong@@0NA) SavingsAccount.obj SavingsAccount And I don't see why I am getting this error. Maybe I don't know something about static variables compared to regular data members that is causing this error. Here is my code: SavingsAccount.h file #ifndef JWONG_SAVINGSACCOUNT_H #define JWONG_SAVINGSACCOUNT_H namespace JWong { class SavingsAccount { public: // default constructor SavingsAccount(); // constructor SavingsAccount(double savingsBalance); double getSavingsBalance(); void setSavingsBalance(double savingsBalance); double calculateMonthlyInterest(); // static functions static void modifyInterestRate(double newInterestRate); static double getAnnualInterestRest(); private: double savingsBalance; // static members static double annualInterestRate; }; } #endif SavingsAccount.cpp file #include <iostream> #include "SavingsAccount.h" // default constructor, set savingsBalance to 0 JWong::SavingsAccount::SavingsAccount() : savingsBalance(0) {} // constructor JWong::SavingsAccount::SavingsAccount(double savingsBalance) : savingsBalance(savingsBalance) {} double JWong::SavingsAccount::getSavingsBalance() { return savingsBalance; } void JWong::SavingsAccount::setSavingsBalance(double savingsBalance) { this->savingsBalance = savingsBalance; } // returns monthly interest and sets savingsBalance to new amount double JWong::SavingsAccount::calculateMonthlyInterest() { double monthlyInterest = savingsBalance * SavingsAccount::annualInterestRate / 12; setSavingsBalance(savingsBalance + monthlyInterest); return monthlyInterest; } void JWong::SavingsAccount::modifyInterestRate(double newInterestRate) { SavingsAccount::annualInterestRate = newInterestRate; } double JWong::SavingsAccount::getAnnualInterestRest() { return SavingsAccount::annualInterestRate; }

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  • getting duplicate array output - java

    - by dowln
    Hello, Can someone could be kind and help me out here. Thanks in advance... My code below outputs the string as duplicates. I don't want to use Sets or ArrayList. I am using java.util.Random. I am trying to write a code that checks if string has already been randomly outputted and if it does, then it won't display. Where I am going wrong and how do I fix this. public class Worldcountries { private static Random nums = new Random(); private static String[] countries = { "America", "Candada", "Chile", "Argentina" }; public static int Dice() { return (generator.nums.nextInt(6) + 1); } public String randomCounties() { String aTemp = " "; int numOfTimes = Dice(); int dup = 0; for(int i=0 ; i<numOfTimes; i++) { // I think it's in the if statement where I am going wrong. if (!countries[i].equals(countries[i])) { i = i + 1; } else { dup--; } // and maybe here aTemp = aTemp + countries[nums.nextInt(countries.length)]; aTemp = aTemp + ","; } return aTemp; } } So the output I am getting (randomly) is, "America, America, Chile" when it should be "America, Chile".

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  • Beginning Java (Working with Arrays; Class Assignment)

    - by Jason
    I am to the point where I feel as if I correctly wrote the code for this homework assignment. We were given a skeleton and 2 classes that we had to import (FileIOHelper and Student). /* * Created: *** put the date here *** * * Author: *** put your name here *** * * The program will read information about students and their * scores from a file, and output the name of each student with * all his/her scores and the total score, plus the average score * of the class, and the name and total score of the students with * the highest and lowest total score. */ // import java.util.Scanner; import java.io.*; // C:\Users\Adam\info.txt public class Lab6 { public static void main(String[] args) throws IOException { // Fill in the body according to the following comments Scanner key boardFile = new Scanner(System.in); // Input file name String filename = getFileName(keyboardFile); //Open the file // Input number of students int numStudents = FileIOHelper.getNumberOfStudents(filename); Student students[] = new Student[numStudents]; // Input all student records and create Student array and // integer array for total scores int totalScore[] = new int[students.length]; for (int i = 0; i < students.length; i++){ for(int j = 1; j < 4; j++){ totalScore[i] = totalScore[i] + students[i].getScore(j); } } // Compute total scores and find students with lowest and // highest total score int maxScore = 0; int minScore = 0; for(int i = 0; i < students.length; i++){ if(totalScore[i] >= totalScore[maxScore]){ maxScore = i; } else if(totalScore[i] <= totalScore[minScore]){ minScore = i; } } // Compute average total score int allScores = 0; int average = 0; for (int i = 0; i < totalScore.length; i++){ allScores = allScores + totalScore[i]; } average = allScores / totalScore.length; // Output results outputResults(students, totalScore, maxScore, minScore, average); } // Given a Scanner in, this method prompts the user to enter // a file name, inputs it, and returns it. private static String getFileName(Scanner in) { // Fill in the body System.out.print("Enter the name of a file: "); String filename = in.next(); return filename; // Do not declare the Scanner variable in this method. // You must use the value this method receives in the // argument (in). } // Given the number of students records n to input, this // method creates an array of Student of the appropriate size, // reads n student records using the FileIOHelper, and stores // them in the array, and finally returns the Student array. private static Student[] getStudents(int n) { Student[] myStudents = new Student[n]; for(int i = 0; i <= n; i++){ myStudents[i] = FileIOHelper.getNextStudent(); } return myStudents; } // Given an array of Student records, an array with the total scores, // the indices in the arrays of the students with the highest and // lowest total scores, and the average total score for the class, // this method outputs a table of all the students appropriately // formatted, plus the total number of students, the average score // of the class, and the name and total score of the students with // the highest and lowest total score. private static void outputResults( Student[] students, int[] totalScores, int maxIndex, int minIndex, int average ) { // Fill in the body System.out.println("\nName \t\tScore1 \tScore2 \tScore3 \tTotal"); System.out.println("--------------------------------------------------------"); for(int i = 0; i < students.length; i++){ outputStudent(students[i], totalScores[i], average); System.out.println(); } System.out.println("--------------------------------------------------------"); outputNumberOfStudents(students.length); outputAverage(average); outputMaxStudent(students[maxIndex], totalScores[maxIndex]); outputMinStudent(students[minIndex], totalScores[minIndex]); System.out.println("--------------------------------------------------------"); } // Given a Student record, the total score for the student, // and the average total score for all the students, this method // outputs one line in the result table appropriately formatted. private static void outputStudent(Student s, int total, int avg) { System.out.print(s.getName() + "\t"); for(int i = 1; i < 4; i++){ System.out.print(s.getScore(i) + "\t"); } System.out.print(total + "\t"); if(total < avg){ System.out.print("-"); }else if(total > avg){ System.out.print("+"); }else{ System.out.print("="); } } // Given the number of students, this method outputs a message // stating what the total number of students in the class is. private static void outputNumberOfStudents(int n) { System.out.println("The total number of students in this class is: \t" + n); } // Given the average total score of all students, this method // outputs a message stating what the average total score of // the class is. private static void outputAverage(int average) { System.out.println("The average total score of the class is: \t" + average); } // Given the Student with highest total score and the student's // total score, this method outputs a message stating the name // of the student and the highest score. private static void outputMaxStudent( Student student, int score ) { System.out.println(student.getName() + " got the maximum total score of: \t" + score); } // Given the Student with lowest total score and the student's // total score, this method outputs a message stating the name // of the student and the lowest score. private static void outputMinStudent( Student student, int score ) { System.out.println(student.getName() + " got the minimum total score of: \t" + score); } } But now I get an error at the line totalScore[i] = totalScore[i] + students[i].getScore(j); Exception in thread "main" java.lang.NullPointerException at Lab6.main(Lab6.java:42)

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  • C++ function not found during compilation

    - by forthewinwin
    For a homework assignment: I'm supposed to create randomized alphabetial keys, print them to a file, and then hash each of them into a hash table using the function "goodHash", found in my below code. When I try to run the below code, it says my "goodHash" "identifier isn't found". What's wrong with my code? #include <iostream> #include <vector> #include <cstdlib> #include "math.h" #include <fstream> #include <time.h> using namespace std; // "makeKey" function to create an alphabetical key // based on 8 randomized numbers 0 - 25. string makeKey() { int k; string key = ""; for (k = 0; k < 8; k++) { int keyNumber = (rand() % 25); if (keyNumber == 0) key.append("A"); if (keyNumber == 1) key.append("B"); if (keyNumber == 2) key.append("C"); if (keyNumber == 3) key.append("D"); if (keyNumber == 4) key.append("E"); if (keyNumber == 5) key.append("F"); if (keyNumber == 6) key.append("G"); if (keyNumber == 7) key.append("H"); if (keyNumber == 8) key.append("I"); if (keyNumber == 9) key.append("J"); if (keyNumber == 10) key.append("K"); if (keyNumber == 11) key.append("L"); if (keyNumber == 12) key.append("M"); if (keyNumber == 13) key.append("N"); if (keyNumber == 14) key.append("O"); if (keyNumber == 15) key.append("P"); if (keyNumber == 16) key.append("Q"); if (keyNumber == 17) key.append("R"); if (keyNumber == 18) key.append("S"); if (keyNumber == 19) key.append("T"); if (keyNumber == 20) key.append("U"); if (keyNumber == 21) key.append("V"); if (keyNumber == 22) key.append("W"); if (keyNumber == 23) key.append("X"); if (keyNumber == 24) key.append("Y"); if (keyNumber == 25) key.append("Z"); } return key; } // "makeFile" function to produce the desired text file. // Note this only works as intended if you include the ".txt" extension, // and that a file of the same name doesn't already exist. void makeFile(string fileName, int n) { ofstream ourFile; ourFile.open(fileName); int k; // For use in below loop to compare with n. int l; // For use in the loop inside the below loop. string keyToPassTogoodHash = ""; for (k = 1; k <= n; k++) { for (l = 0; l < 8; l++) { // For-loop to write to the file ONE key ourFile << makeKey()[l]; keyToPassTogoodHash += (makeKey()[l]); } ourFile << " " << k << "\n";// Writes two spaces and the data value goodHash(keyToPassTogoodHash); // I think this has to do with the problem makeKey(); // Call again to make a new key. } } // Primary function to create our desired file! void mainFunction(string fileName, int n) { makeKey(); makeFile(fileName, n); } // Hash Table for Part 2 struct Node { int key; string value; Node* next; }; const int hashTableSize = 10; Node* hashTable[hashTableSize]; // "goodHash" function for Part 2 void goodHash(string key) { int x = 0; int y; int keyConvertedToNumber = 0; // For-loop to produce a numeric value based on the alphabetic key, // which is then hashed into hashTable using the hash function // declared below the loop (hashFunction). for (y = 0; y < 8; y++) { if (key[y] == 'A' || 'B' || 'C') x = 0; if (key[y] == 'D' || 'E' || 'F') x = 1; if (key[y] == 'G' || 'H' || 'I') x = 2; if (key[y] == 'J' || 'K' || 'L') x = 3; if (key[y] == 'M' || 'N' || 'O') x = 4; if (key[y] == 'P' || 'Q' || 'R') x = 5; if (key[y] == 'S' || 'T') x = 6; if (key[y] == 'U' || 'V') x = 7; if (key[y] == 'W' || 'X') x = 8; if (key[y] == 'Y' || 'Z') x = 9; keyConvertedToNumber = x + keyConvertedToNumber; } int hashFunction = keyConvertedToNumber % hashTableSize; Node *temp; temp = new Node; temp->value = key; temp->next = hashTable[hashFunction]; hashTable[hashFunction] = temp; } // First two lines are for Part 1, to call the functions key to Part 1. int main() { srand ( time(NULL) ); // To make sure our randomization works. mainFunction("sandwich.txt", 5); // To test program cin.get(); return 0; } I realize my code is cumbersome in some sections, but I'm a noob at C++ and don't know much to do it better. I'm guessing another way I could do it is to AFTER writing the alphabetical keys to the file, read them from the file and hash each key as I do that, but I wouldn't know how to go about coding that.

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  • Modifying and Manipulating a interactive bezier curve

    - by rachel
    This is a homework question and I'm having a lot of trouble with it - I've managed to do some of it but still cant finish it - can i Please get some help. Q1. Bezier Curves The following example allows you to interactively control a bezier curve by dragging the control points Cubic.java Replace the call to draw the cubic shape (big.draw(cubic)), by your own function to draw a bezier by the recursive split method. Finally, add the ability to create a longer Bezier curve by adding more control points to create a second curve. Cubic.java import java.awt.*; import javax.swing.*; import java.awt.event.*; import java.applet.Applet; import java.awt.geom.*; import java.awt.image.BufferedImage; public class Cubic extends JApplet{ static protected JLabel label; CubicPanel cubicPanel; public void init(){ //Initialize the layout. getContentPane().setLayout(new BorderLayout()); cubicPanel = new CubicPanel(); cubicPanel.setBackground(Color.white); getContentPane().add(cubicPanel); label = new JLabel("Drag the points to adjust the curve."); getContentPane().add("South", label); } public static void main(String s[]) { JFrame f = new JFrame("Cubic"); f.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) {System.exit(0);} }); JApplet applet = new Cubic(); f.getContentPane().add(applet, BorderLayout.CENTER); applet.init(); f.setSize(new Dimension(350,250)); f.setVisible(true); } } class CubicPanel extends JPanel implements MouseListener, MouseMotionListener{ BufferedImage bi; Graphics2D big; int x, y; Rectangle area, startpt, endpt, onept, twopt, rect; CubicCurve2D.Double cubic = new CubicCurve2D.Double(); Point2D.Double start, end, one, two, point; boolean firstTime = true; boolean pressOut = false; public CubicPanel(){ setBackground(Color.white); addMouseMotionListener(this); addMouseListener(this); start = new Point2D.Double(); one = new Point2D.Double(); two = new Point2D.Double(); end = new Point2D.Double(); cubic.setCurve(start, one, two, end); startpt = new Rectangle(0, 0, 8, 8); endpt = new Rectangle(0, 0, 8, 8); onept = new Rectangle(0, 0, 8, 8); twopt = new Rectangle(0, 0, 8, 8); } public void mousePressed(MouseEvent e){ x = e.getX(); y = e.getY(); if(startpt.contains(x, y)){ rect = startpt; point = start; x = startpt.x - e.getX(); y = startpt.y - e.getY(); updateLocation(e); } else if(endpt.contains(x, y)){ rect = endpt; point = end; x = endpt.x - e.getX(); y = endpt.y - e.getY(); updateLocation(e); } else if(onept.contains(x, y)){ rect = onept; point = one; x = onept.x - e.getX(); y = onept.y - e.getY(); updateLocation(e); } else if(twopt.contains(x, y)){ rect = twopt; point = two; x = twopt.x - e.getX(); y = twopt.y - e.getY(); updateLocation(e); } else { pressOut = true; } } public void mouseDragged(MouseEvent e){ if(!pressOut) { updateLocation(e); } } public void mouseReleased(MouseEvent e){ if(startpt.contains(e.getX(), e.getY())){ rect = startpt; point = start; updateLocation(e); } else if(endpt.contains(e.getX(), e.getY())){ rect = endpt; point = end; updateLocation(e); } else if(onept.contains(e.getX(), e.getY())){ rect = onept; point = one; updateLocation(e); } else if(twopt.contains(e.getX(), e.getY())){ rect = twopt; point = two; updateLocation(e); } else { pressOut = false; } } public void mouseMoved(MouseEvent e){} public void mouseClicked(MouseEvent e){} public void mouseExited(MouseEvent e){} public void mouseEntered(MouseEvent e){} public void updateLocation(MouseEvent e){ rect.setLocation((x + e.getX())-4, (y + e.getY())-4); point.setLocation(x + e.getX(), y + e.getY()); checkPoint(); cubic.setCurve(start, one, two, end); repaint(); } public void paintComponent(Graphics g){ super.paintComponent(g); update(g); } public void update(Graphics g){ Graphics2D g2 = (Graphics2D)g; Dimension dim = getSize(); int w = dim.width; int h = dim.height; if(firstTime){ // Create the offsecren graphics to render to bi = (BufferedImage)createImage(w, h); big = bi.createGraphics(); // Get some initial positions for the control points start.setLocation(w/2-50, h/2); end.setLocation(w/2+50, h/2); one.setLocation((int)(start.x)+25, (int)(start.y)-25); two.setLocation((int)(end.x)-25, (int)(end.y)+25); // Set the initial positions of the squares that are // drawn at the control points startpt.setLocation((int)((start.x)-4), (int)((start.y)-4)); endpt.setLocation((int)((end.x)-4), (int)((end.y)-4)); onept.setLocation((int)((one.x)-4), (int)((one.y)-4)); twopt.setLocation((int)((two.x)-4), (int)((two.y)-4)); // Initialise the CubicCurve2D cubic.setCurve(start, one, two, end); // Set some defaults for Java2D big.setColor(Color.black); big.setStroke(new BasicStroke(5.0f)); big.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); area = new Rectangle(dim); firstTime = false; } // Clears the rectangle that was previously drawn. big.setColor(Color.white); big.clearRect(0, 0, area.width, area.height); // Set the colour for the bezier big.setPaint(Color.black); // Replace the following line by your own function to // draw the bezier specified by start, one, two, end big.draw(cubic); // Draw the control points big.setPaint(Color.red); big.fill(startpt); big.setPaint(Color.magenta); big.fill(endpt); big.setPaint(Color.blue); big.fill(onept); big.setPaint(new Color(0, 200, 0)); big.fill(twopt); // Draws the buffered image to the screen. g2.drawImage(bi, 0, 0, this); } /* Checks if the rectangle is contained within the applet * window. If the rectangle is not contained withing the * applet window, it is redrawn so that it is adjacent to the * edge of the window and just inside the window. */ void checkPoint(){ if (area == null) { return; } if((area.contains(rect)) && (area.contains(point))){ return; } int new_x = rect.x; int new_y = rect.y; double new_px = point.x; double new_py = point.y; if((rect.x+rect.width)>area.getWidth()){ new_x = (int)area.getWidth()-(rect.width-1); } if(point.x > area.getWidth()){ new_px = (int)area.getWidth()-1; } if(rect.x < 0){ new_x = -1; } if(point.x < 0){ new_px = -1; } if((rect.y+rect.width)>area.getHeight()){ new_y = (int)area.getHeight()-(rect.height-1); } if(point.y > area.getHeight()){ new_py = (int)area.getHeight()-1; } if(rect.y < 0){ new_y = -1; } if(point.y < 0){ new_py = -1; } rect.setLocation(new_x, new_y); point.setLocation(new_px, new_py); } }

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  • Beginner question: ArrayList can't seem to get it right! Pls help

    - by elementz
    I have been staring at this code all day now, but just can't get it right. ATM I am just pushing codeblocks around without being able to concentrate anymore, with the due time being within almost an hour... So you guys are my last resort here. I am supposed to create a few random balls on a canvas, those balls being stored within an ArrayList (I hope an ArrayList is suitable here: the alternative options to choose from were HashSet and HashMap). Now, whatever I do, I get the differently colored balls at the top of my canvas, but they just get stuck there and refuse to move at all. Apart from that I now get a ConcurrentModificationException, when running the code: java.util.ConcurrentModificationException at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372) at java.util.AbstractList$Itr.next(AbstractList.java:343) at BallDemo.bounce(BallDemo.java:109) Reading up on that exception, I found out that one can make sure ArrayList is accessed in a threadsafe manner by somehow synchronizing access. But since I have remember fellow students doing without synchronizing, my guess is, that it would actually be the wrong path to go. Maybe you guys could help me get this to work, I at least need those stupid balls to move ;-) /** * Simulate random bouncing balls */ public void bounce(int count) { int ground = 400; // position of the ground line System.out.println(count); myCanvas.setVisible(true); // draw the ground myCanvas.drawLine(50, ground, 550, ground); // Create an ArrayList of type BouncingBalls ArrayList<BouncingBall>balls = new ArrayList<BouncingBall>(); for (int i = 0; i < count; i++){ Random numGen = new Random(); // Creating a random color. Color col = new Color(numGen.nextInt(256), numGen.nextInt(256), numGen.nextInt(256)); // creating a random x-coordinate for the balls int ballXpos = numGen.nextInt(550); BouncingBall bBall = new BouncingBall(ballXpos, 80, 20, col, ground, myCanvas); // adding balls to the ArrayList balls.add(bBall); bBall.draw(); boolean finished = false; } for (BouncingBall bBall : balls){ bBall.move(); } } This would be the original unmodified method we got from our teacher, which only creates two balls: /** * Simulate two bouncing balls */ public void bounce() { int ground = 400; // position of the ground line myCanvas.setVisible(true); myCanvas.drawLine(50, ground, 550, ground); // draw the ground // crate and show the balls BouncingBall ball = new BouncingBall(50, 50, 16, Color.blue, ground, myCanvas); ball.draw(); BouncingBall ball2 = new BouncingBall(70, 80, 20, Color.red, ground, myCanvas); ball2.draw(); // make them bounce boolean finished = false; while(!finished) { myCanvas.wait(50); // small delay ball.move(); ball2.move(); // stop once ball has travelled a certain distance on x axis if(ball.getXPosition() >= 550 && ball2.getXPosition() >= 550) { finished = true; } } ball.erase(); ball2.erase(); } }

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  • running multi threads in Java

    - by owca
    My task is to simulate activity of couple of persons. Each of them has few activities to perform in some random time: fast (0-5s), medium(5-10s), slow(10-20s) and very slow(20-30s). Each person performs its task independently in the same time. At the beginning of new task I should print it's random time, start the task and then after time passes show next task's time and start it. I've written run() function that counts time, but now it looks like threads are done one after another and not in the same time or maybe they're just printed in this way. public class People{ public static void main(String[] args){ Task tasksA[]={new Task("washing","fast"), new Task("reading","slow"), new Task("shopping","medium")}; Task tasksM[]={new Task("sleeping zzzzzzzzzz","very slow"), new Task("learning","slow"), new Task(" :** ","slow"), new Task("passing an exam","slow") }; Task tasksJ[]={new Task("listening music","medium"), new Task("doing nothing","slow"), new Task("walking","medium") }; BusyPerson friends[]={ new BusyPerson("Alice",tasksA), new BusyPerson("Mark",tasksM), new BusyPerson("John",tasksJ)}; System.out.println("STARTING....................."); for(BusyPerson f: friends) (new Thread(f)).start(); System.out.println("DONE........................."); } } class Task { private String task; private int time; private Task[]tasks; public Task(String t, String s){ task = t; Speed speed = new Speed(); time = speed.getSpeed(s); } public Task(Task[]tab){ Task[]table=new Task[tab.length]; for(int i=0; i < tab.length; i++){ table[i] = tab[i]; } this.tasks = table; } } class Speed { private static String[]hows = {"fast","medium","slow","very slow"}; private static int[]maxs = {5000, 10000, 20000, 30000}; public Speed(){ } public static int getSpeed( String speedString){ String s = speedString; int up_limit=0; int down_limit=0; int time=0; //get limits of time for(int i=0; i<hows.length; i++){ if(s.equals(hows[i])){ up_limit = maxs[i]; if(i>0){ down_limit = maxs[i-1]; } else{ down_limit = 0; } } } //get random time within the limits Random rand = new Random(); time = rand.nextInt(up_limit) + down_limit; return time; } } class BusyPerson implements Runnable { private String name; private Task[] person_tasks; private BusyPerson[]persons; public BusyPerson(String s, Task[]t){ name = s; person_tasks = t; } public BusyPerson(BusyPerson[]tab){ BusyPerson[]table=new BusyPerson[tab.length]; for(int i=0; i < tab.length; i++){ table[i] = tab[i]; } this.persons = table; } public void run() { int time = 0; double t1=0; for(Task t: person_tasks){ t1 = (double)t.time/1000; System.out.println(name+" is... "+t.task+" "+t.speed+ " ("+t1+" sec)"); while (time == t.time) { try { Thread.sleep(10); } catch(InterruptedException exc) { System.out.println("End of thread."); return; } time = time + 100; } } } } And my output : STARTING..................... DONE......................... Mark is... sleeping zzzzzzzzzz very slow (36.715 sec) Mark is... learning slow (10.117 sec) Mark is... :** slow (29.543 sec) Mark is... passing an exam slow (23.429 sec) Alice is... washing fast (1.209 sec) Alice is... reading slow (23.21 sec) Alice is... shopping medium (11.237 sec) John is... listening music medium (8.263 sec) John is... doing nothing slow (13.576 sec) John is... walking medium (11.322 sec) Whilst it should be like this : STARTING..................... DONE......................... John is... listening music medium (7.05 sec) Alice is... washing fast (3.268 sec) Mark is... sleeping zzzzzzzzzz very slow (23.71 sec) Alice is... reading slow (15.516 sec) John is... doing nothing slow (13.692 sec) Alice is... shopping medium (8.371 sec) Mark is... learning slow (13.904 sec) John is... walking medium (5.172 sec) Mark is... :** slow (12.322 sec) Mark is... passing an exam very slow (27.1 sec)

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  • Finding the heaviest length-constrained path in a weighted Binary Tree

    - by Hristo
    UPDATE I worked out an algorithm that I think runs in O(n*k) running time. Below is the pseudo-code: routine heaviestKPath( T, k ) // create 2D matrix with n rows and k columns with each element = -8 // we make it size k+1 because the 0th column must be all 0s for a later // function to work properly and simplicity in our algorithm matrix = new array[ T.getVertexCount() ][ k + 1 ] (-8); // set all elements in the first column of this matrix = 0 matrix[ n ][ 0 ] = 0; // fill our matrix by traversing the tree traverseToFillMatrix( T.root, k ); // consider a path that would arc over a node globalMaxWeight = -8; findArcs( T.root, k ); return globalMaxWeight end routine // node = the current node; k = the path length; node.lc = node’s left child; // node.rc = node’s right child; node.idx = node’s index (row) in the matrix; // node.lc.wt/node.rc.wt = weight of the edge to left/right child; routine traverseToFillMatrix( node, k ) if (node == null) return; traverseToFillMatrix(node.lc, k ); // recurse left traverseToFillMatrix(node.rc, k ); // recurse right // in the case that a left/right child doesn’t exist, or both, // let’s assume the code is smart enough to handle these cases matrix[ node.idx ][ 1 ] = max( node.lc.wt, node.rc.wt ); for i = 2 to k { // max returns the heavier of the 2 paths matrix[node.idx][i] = max( matrix[node.lc.idx][i-1] + node.lc.wt, matrix[node.rc.idx][i-1] + node.rc.wt); } end routine // node = the current node, k = the path length routine findArcs( node, k ) if (node == null) return; nodeMax = matrix[node.idx][k]; longPath = path[node.idx][k]; i = 1; j = k-1; while ( i+j == k AND i < k ) { left = node.lc.wt + matrix[node.lc.idx][i-1]; right = node.rc.wt + matrix[node.rc.idx][j-1]; if ( left + right > nodeMax ) { nodeMax = left + right; } i++; j--; } // if this node’s max weight is larger than the global max weight, update if ( globalMaxWeight < nodeMax ) { globalMaxWeight = nodeMax; } findArcs( node.lc, k ); // recurse left findArcs( node.rc, k ); // recurse right end routine Let me know what you think. Feedback is welcome. I think have come up with two naive algorithms that find the heaviest length-constrained path in a weighted Binary Tree. Firstly, the description of the algorithm is as follows: given an n-vertex Binary Tree with weighted edges and some value k, find the heaviest path of length k. For both algorithms, I'll need a reference to all vertices so I'll just do a simple traversal of the Tree to have a reference to all vertices, with each vertex having a reference to its left, right, and parent nodes in the tree. Algorithm 1 For this algorithm, I'm basically planning on running DFS from each node in the Tree, with consideration to the fixed path length. In addition, since the path I'm looking for has the potential of going from left subtree to root to right subtree, I will have to consider 3 choices at each node. But this will result in a O(n*3^k) algorithm and I don't like that. Algorithm 2 I'm essentially thinking about using a modified version of Dijkstra's Algorithm in order to consider a fixed path length. Since I'm looking for heaviest and Dijkstra's Algorithm finds the lightest, I'm planning on negating all edge weights before starting the traversal. Actually... this doesn't make sense since I'd have to run Dijkstra's on each node and that doesn't seem very efficient much better than the above algorithm. So I guess my main questions are several. Firstly, do the algorithms I've described above solve the problem at hand? I'm not totally certain the Dijkstra's version will work as Dijkstra's is meant for positive edge values. Now, I am sure there exist more clever/efficient algorithms for this... what is a better algorithm? I've read about "Using spine decompositions to efficiently solve the length-constrained heaviest path problem for trees" but that is really complicated and I don't understand it at all. Are there other algorithms that tackle this problem, maybe not as efficiently as spine decomposition but easier to understand? Thanks.

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  • Generating moderately interesting images

    - by Williham Totland
    Abstract: Can you propose a mathematical-ish algorithm over a plane of pixels that will generate a moderately interesting image, preferably one that on the whole resembles something? The story thus far: Once upon a time I decided in an effort to reduce cycle waste on my (admittedly too) numerous computers, and set out to generate images in a moderately interesting fashion; using a PRNG and some clever math to create images that would, on the whole, resemble something. Or at least, that was the plan. As it turns out, clever math requires being a clever mathematician; this I am not. At some length I arrived at a method that preferred straight lines (as these are generally the components of which our world is made), perhaps too strongly. The result is mildly interesting; resembling, perhaps, city grids as such: Now for the question proper: Given the source code of this little program; can you improve upon it and propose a method that gives somewhat more interesting results? (e.g. not city grids, but perhaps faces, animals, geography, what have you) This is also meant as a sort of challenge; I suppose and as such I've set down some completely arbitrary and equally optional rules: The comments in the code says it all really. Suggestions and "solutions" should edit the algorithm itself, not the surrounding framework, except as for to fix errors that prevents the sample from compiling. The code should compile cleanly with a standard issue C compiler. (If the example provided doesn't, oops! Tell me, and I'll fix. :) The method should, though again, this is optional, not need to elicit help from your friendly neighborhood math library. Solutions should probably be deliverable by simply yanking out whatever is between the snip lines (the ones that say you should not edit above and below, respectively), with a statement to the effect of what you need to add to the preamble in particular. The code requires a C compiler and libpng to build; I'm not entirely confident that the MinGW compiler provides the necessities, but I would be surprised if it didn't. For Debian you'll want the libpng-dev package, and for Mac OS X you'll want the XCode tools.. The source code can be downloaded here. Warning: Massive code splurge incoming! // compile with gcc -o imggen -lpng imggen.c // optionally with -DITERATIONS=x, where x is an appropriate integer // If you're on a Mac or using MinGW, you may have to fiddle with the linker flags to find the library and includes. #include <stdio.h> #include <stdlib.h> #include <png.h> #ifdef ITERATIONS #define REPEAT #endif // ITERATIONS // YOU MAY CHANGE THE FOLLOWING DEFINES #define WIDTH 320 #define HEIGHT 240 // YOU MAY REPLACE THE FOLLOWING DEFINES AS APPROPRIATE #define INK 16384 void writePNG (png_bytepp imageBuffer, png_uint_32 width, png_uint_32 height, int iteration) { char *fname; asprintf(&fname, "out.%d.png", iteration); FILE *fp = fopen(fname, "wb"); if (!fp) return; png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); png_infop info_ptr = png_create_info_struct(png_ptr); png_init_io(png_ptr, fp); png_set_filter(png_ptr, PNG_FILTER_TYPE_DEFAULT, PNG_FILTER_NONE); png_set_compression_level(png_ptr, Z_BEST_COMPRESSION); png_set_IHDR(png_ptr, info_ptr, width, height, 8, PNG_COLOR_TYPE_GRAY, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT); png_set_rows(png_ptr, info_ptr, imageBuffer); png_set_invert_mono(png_ptr); /// YOU MAY COMMENT OUT THIS LINE png_write_png(png_ptr, info_ptr, PNG_TRANSFORM_IDENTITY, NULL); png_destroy_write_struct(&png_ptr, &info_ptr); fclose(fp); free(fname); } int main (int argc, const char * argv[]) { png_uint_32 height = HEIGHT, width = WIDTH; int iteration = 1; #ifdef REPEAT for (iteration = 1; iteration <= ITERATIONS; iteration++) { #endif // REPEAT png_bytepp imageBuffer = malloc(sizeof(png_bytep) * height); for (png_uint_32 i = 0; i < height; i++) { imageBuffer[i] = malloc(sizeof(png_byte) * width); for (png_uint_32 j = 0; j < width; j++) { imageBuffer[i][j] = 0; } } /// CUT ACROSS THE DASHED LINES /// ------------------------------------------- /// NO EDITING ABOVE THIS LINE; EXCEPT AS NOTED int ink = INK; int x = rand() % width, y = rand() % height; int xdir = (rand() % 2)?1:-1; int ydir = (rand() % 2)?1:-1; while (ink) { imageBuffer[y][x] = 255; --ink; xdir += (rand() % 2)?(1):(-1); ydir += (rand() % 2)?(1):(-1); if (ydir > 0) { ++y; } else if (ydir < 0) { --y; } if (xdir > 0) { ++x; } else if (xdir < 0) { --x; } if (x == -1 || y == -1 || x == width || y == height || x == y && x == 0) { x = rand() % width; y = rand() % height; xdir = (rand() % 2)?1:-1; ydir = (rand() % 2)?1:-1; } } /// NO EDITING BELOW THIS LINE /// ------------------------------------------- writePNG(imageBuffer, width, height, iteration); for (png_uint_32 i = 0; i < height; i++) { free(imageBuffer[i]); } free(imageBuffer); #ifdef REPEAT } #endif // REPEAT return 0; } Note: While this question doesn't strictly speaking seem "answerable" as such; I still believe that it can give rise to some manner of "right" answer. Maybe. Happy hunting.

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  • VHDL - Problem with std_logic_vector

    - by wretrOvian
    Hi, i'm coding a 4-bit binary adder with accumulator: library ieee; use ieee.std_logic_1164.all; entity binadder is port(n,clk,sh:in bit; x,y:inout std_logic_vector(3 downto 0); co:inout bit; done:out bit); end binadder; architecture binadder of binadder is signal state: integer range 0 to 3; signal sum,cin:bit; begin sum<= (x(0) xor y(0)) xor cin; co<= (x(0) and y(0)) or (y(0) and cin) or (x(0) and cin); process begin wait until clk='0'; case state is when 0=> if(n='1') then state<=1; end if; when 1|2|3=> if(sh='1') then x<= sum & x(3 downto 1); y<= y(0) & y(3 downto 1); cin<=co; end if; if(state=3) then state<=0; end if; end case; end process; done<='1' when state=3 else '0'; end binadder; The output : -- Compiling architecture binadder of binadder ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(15): No feasible entries for infix operator "xor". ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(15): Type error resolving infix expression "xor" as type std.standard.bit. ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(16): No feasible entries for infix operator "and". ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(16): Bad expression in right operand of infix expression "or". ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(16): No feasible entries for infix operator "and". ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(16): Bad expression in left operand of infix expression "or". ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(16): Bad expression in right operand of infix expression "or". ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(16): Type error resolving infix expression "or" as type std.standard.bit. ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(28): No feasible entries for infix operator "&". ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(28): Type error resolving infix expression "&" as type ieee.std_logic_1164.std_logic_vector. ** Error: C:/Modeltech_pe_edu_6.5a/examples/binadder.vhdl(39): VHDL Compiler exiting I believe i'm not handling std_logic_vector's correctly. Please tell me how? :(

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  • These are few objective type questions which i was not able to find the solution [closed]

    - by Tarun
    1. Which of the following advantages does System.Collections.IDictionaryEnumerator provide over System.Collections.IEnumerator? a. It adds properties for direct access to both the Key and the Value b. It is optimized to handle the structure of a Dictionary. c. It provides properties to determine if the Dictionary is enumerated in Key or Value order d. It provides reverse lookup methods to distinguish a Key from a specific Value 2. When Implementing System.EnterpriseServices.ServicedComponent derived classes, which of the following statements are true? a. Enabling object pooling requires an attribute on the class and the enabling of pooling in the COM+ catalog. b. Methods can be configured to automatically mark a transaction as complete by the use of attributes. c. You can configure authentication using the AuthenticationOption when the ActivationMode is set to Library. d. You can control the lifecycle policy of an individual instance using the SetLifetimeService method. 3. Which of the following are true regarding event declaration in the code below? class Sample { event MyEventHandlerType MyEvent; } a. MyEventHandlerType must be derived from System.EventHandler or System.EventHandler<TEventArgs> b. MyEventHandlerType must take two parameters, the first of the type Object, and the second of a class derived from System.EventArgs c. MyEventHandlerType may have a non-void return type d. If MyEventHandlerType is a generic type, event declaration must use a specialization of that type. e. MyEventHandlerType cannot be declared static 4. Which of the following statements apply to developing .NET code, using .NET utilities that are available with the SDK or Visual Studio? a. Developers can create assemblies directly from the MSIL Source Code. b. Developers can examine PE header information in an assembly. c. Developers can generate XML Schemas from class definitions contained within an assembly. d. Developers can strip all meta-data from managed assemblies. e. Developers can split an assembly into multiple assemblies. 5. Which of the following characteristics do classes in the System.Drawing namespace such as Brush,Font,Pen, and Icon share? a. They encapsulate native resource and must be properly Disposed to prevent potential exhausting of resources. b. They are all MarshalByRef derived classes, but functionality across AppDomains has specific limitations. c. You can inherit from these classes to provide enhanced or customized functionality 6. Which of the following are required to be true by objects which are going to be used as keys in a System.Collections.HashTable? a. They must handle case-sensitivity identically in both the GetHashCode() and Equals() methods. b. Key objects must be immutable for the duration they are used within a HashTable. c. Get HashCode() must be overridden to provide the same result, given the same parameters, regardless of reference equalityl unless the HashTable constructor is provided with an IEqualityComparer parameter. d. Each Element in a HashTable is stored as a Key/Value pair of the type System.Collections.DictionaryElement e. All of the above 7. Which of the following are true about Nullable types? a. A Nullable type is a reference type. b. A Nullable type is a structure. c. An implicit conversion exists from any non-nullable value type to a nullable form of that type. d. An implicit conversion exists from any nullable value type to a non-nullable form of that type. e. A predefined conversion from the nullable type S? to the nullable type T? exists if there is a predefined conversion from the non-nullable type S to the non-nullable type T 8. When using an automatic property, which of the following statements is true? a. The compiler generates a backing field that is completely inaccessible from the application code. b. The compiler generates a backing field that is a private instance member with a leading underscore that can be programmatically referenced. c. The compiler generates a backing field that is accessible via reflection d. The compiler generates a code that will store the information separately from the instance to ensure its security. 9. Which of the following does using Initializer Syntax with a collection as shown below require? CollectionClass numbers = new CollectionClass { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; a. The Collection Class must implement System.Collections.Generic.ICollection<T> b. The Collection Class must implement System.Collections.Generic.IList<T> c. Each of the Items in the Initializer List will be passed to the Add<T>(T item) method d. The items in the initializer will be treated as an IEnumerable<T> and passed to the collection constructor+K110 10. What impact will using implicitly typed local variables as in the following example have? var sample = "Hello World"; a. The actual type is determined at compilation time, and has no impact on the runtime b. The actual type is determined at runtime, and late binding takes effect c. The actual type is based on the native VARIANT concept, and no binding to a specific type takes place. d. "var" itself is a specific type defined by the framework, and no special binding takes place 11. Which of the following is not supported by remoting object types? a. well-known singleton b. well-known single call c. client activated d. context-agile 12. In which of the following ways do structs differ from classes? a. Structs can not implement interfaces b. Structs cannot inherit from a base struct c. Structs cannot have events interfaces d. Structs cannot have virtual methods 13. Which of the following is not an unboxing conversion? a. void Sample1(object o) { int i = (int)o; } b. void Sample1(ValueType vt) { int i = (int)vt; } c. enum E { Hello, World} void Sample1(System.Enum et) { E e = (E) et; } d. interface I { int Value { get; set; } } void Sample1(I vt) { int i = vt.Value; } e. class C { public int Value { get; set; } } void Sample1(C vt) { int i = vt.Value; } 14. Which of the following are characteristics of the System.Threading.Timer class? a. The method provided by the TimerCallback delegate will always be invoked on the thread which created the timer. b. The thread which creates the timer must have a message processing loop (i.e. be considered a UI thread) c. The class contains protection to prevent reentrancy to the method provided by the TimerCallback delegate d. You can receive notification of an instance being Disposed by calling an overload of the Dispose method. 15. What is the proper declaration of a method which will handle the following event? Class MyClass { public event EventHandler MyEvent; } a. public void A_MyEvent(object sender, MyArgs e) { } b. public void A_MyEvent(object sender, EventArgs e) { } c. public void A_MyEvent(MyArgs e) { } d. public void A_MyEvent(MyClass sender,EventArgs e) { } 16. Which of the following scenarios are applicable to Window Workflow Foundation? a. Document-centric workflows b. Human workflows c. User-interface page flows d. Builtin support for communications across multiple applications and/or platforms e. All of the above 17. When using an automatic property, which of the following statements is true? a. The compiler generates a backing field that is completely inaccessible from the application code. b. The compiler generates a backing field that is a private instance member with a leading underscore that can be programmatically referenced. c. The compiler generates a backing field that is accessible via reflection d. The compiler generates a code that will store the information separately from the instance to ensure its security. 18 While using the capabilities supplied by the System.Messaging classes, which of the following are true? a. Information must be explicitly converted to/from a byte stream before it uses the MessageQueue class b. Invoking the MessageQueue.Send member defaults to using the System.Messaging.XmlMessageFormatter to serialize the object. c. Objects must be XMLSerializable in order to be transferred over a MessageQueue instance. d. The first entry in a MessageQueue must be removed from the queue before the next entry can be accessed e. Entries removed from a MessageQueue within the scope of a transaction, will be pushed back into the front of the queue if the transaction fails. 19. Which of the following are true about declarative attributes? a. They must be inherited from the System.Attribute. b. Attributes are instantiated at the same time as instances of the class to which they are applied. c. Attribute classes may be restricted to be applied only to application element types. d. By default, a given attribute may be applied multiple times to the same application element. 20. When using version 3.5 of the framework in applications which emit a dynamic code, which of the following are true? a. A Partial trust code can not emit and execute a code b. A Partial trust application must have the SecurityCriticalAttribute attribute have called Assert ReflectionEmit permission c. The generated code no more permissions than the assembly which emitted it. d. It can be executed by calling System.Reflection.Emit.DynamicMethod( string name, Type returnType, Type[] parameterTypes ) without any special permissions Within Windows Workflow Foundation, Compensating Actions are used for: a. provide a means to rollback a failed transaction b. provide a means to undo a successfully committed transaction later c. provide a means to terminate an in process transaction d. achieve load balancing by adapting to the current activity 21. What is the proper declaration of a method which will handle the following event? Class MyClass { public event EventHandler MyEvent; } a. public void A_MyEvent(object sender, MyArgs e) { } b. public void A_MyEvent(object sender, EventArgs e) { } c. public void A_MyEvent(MyArgs e) { } d. public void A_MyEvent(MyClass sender,EventArgs e) { } 22. Which of the following controls allows the use of XSL to transform XML content into formatted content? a. System.Web.UI.WebControls.Xml b. System.Web.UI.WebControls.Xslt c. System.Web.UI.WebControls.Substitution d. System.Web.UI.WebControls.Transform 23. To which of the following do automatic properties refer? a. You declare (explicitly or implicitly) the accessibility of the property and get and set accessors, but do not provide any implementation or backing field b. You attribute a member field so that the compiler will generate get and set accessors c. The compiler creates properties for your class based on class level attributes d. They are properties which are automatically invoked as part of the object construction process 24. Which of the following are true about Nullable types? a. A Nullable type is a reference type. b. An implicit conversion exists from any non-nullable value type to a nullable form of that type. c. A predefined conversion from the nullable type S? to the nullable type T? exists if there is a predefined conversion from the non-nullable type S to the non-nullable type T 25. When using an automatic property, which of the following statements is true? a. The compiler generates a backing field that is completely inaccessible from the application code. b. The compiler generates a backing field that is accessible via reflection. c. The compiler generates a code that will store the information separately from the instance to ensure its security. 26. When using an implicitly typed array, which of the following is most appropriate? a. All elements in the initializer list must be of the same type. b. All elements in the initializer list must be implicitly convertible to a known type which is the actual type of at least one member in the initializer list c. All elements in the initializer list must be implicitly convertible to common type which is a base type of the items actually in the list 27. Which of the following is false about anonymous types? a. They can be derived from any reference type. b. Two anonymous types with the same named parameters in the same order declared in different classes have the same type. c. All properties of an anonymous type are read/write. 28. Which of the following are true about Extension methods. a. They can be declared either static or instance members b. They must be declared in the same assembly (but may be in different source files) c. Extension methods can be used to override existing instance methods d. Extension methods with the same signature for the same class may be declared in multiple namespaces without causing compilation errors

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  • What are the advantages and disadvantages of Dojo, jQuery and Ext JS

    - by easoncyh
    This is a question asked in one of my lectures as a bonus. That means student giving the most appropriate answer will get extra credit. I have used jQuery before for a try and I have found jQuery to be extremely useful! However, I have not never used neither Dojo and Ext JS, can anyone please tell me the advantages and disadvantages of them? Thank you in advance!

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  • Dijkstra's Bankers Algorithm

    - by idea_
    Could somebody please provide a step-through approach to solving the following problem using the Banker's Algorithm? How do I determine whether a "safe-state" exists? What is meant when a process can "run to completion"? In this example, I have four processes and 10 instances of the same resource. Resources Allocated | Resources Needed Process A 1 6 Process B 1 5 Process C 2 4 Process D 4 7

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  • Card Shuffling in C#

    - by Jeff
    I am trying to write a code for a project that lists the contents of a deck of cards, asks how much times the person wants to shuffle the deck, and then shuffles them. It has to use a method to create two random integers using the System.Random class. These are my classes: Program.cs: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication3 { class Program { static void Main(string[] args) { Deck mydeck = new Deck(); foreach (Card c in mydeck.Cards) { Console.WriteLine(c); } Console.WriteLine("How Many Times Do You Want To Shuffle?"); } } } Deck.cs: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication3 { class Deck { Card[] cards = new Card[52]; string[] numbers = new string[] { "2", "3", "4", "5", "6", "7", "8", "9", "J", "Q", "K" }; public Deck() { int i = 0; foreach(string s in numbers) { cards[i] = new Card(Suits.Clubs, s); i++; } foreach (string s in numbers) { cards[i] = new Card(Suits.Spades, s); i++; } foreach (string s in numbers) { cards[i] = new Card(Suits.Hearts, s); i++; } foreach (string s in numbers) { cards[i] = new Card(Suits.Diamonds, s); i++; } } public Card[] Cards { get { return cards; } } } } classes.cs: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication3 { enum Suits { Hearts, Diamonds, Spades, Clubs } } Card.cs: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ConsoleApplication3 { class Card { protected Suits suit; protected string cardvalue; public Card() { } public Card(Suits suit2, string cardvalue2) { suit = suit2; cardvalue = cardvalue2; } public override string ToString() { return string.Format("{0} of {1}", cardvalue, suit); } } } Please tell me how to make the cards shuffle as much as the person wants and then list the shuffled cards. Sorry about the formatting im new to this site.

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  • OO design - car rental

    - by gkid123
    AnHow would you implement the following car hierarchy along with the accessor functions and a CarRental class which contains the container to store them? A car rental company wants to keep track of its cars. Each vehicle has a license plate and a brand. Currently the company has SUV and Sedans. SUV have an optional third row seat, sedan’s have an optional sport package. Each car can be queried to inquire the number of passengers it can carry.

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