Factorial - Writing Iterative Program Recursively
Apr 30, 2015
It was quite recently that Data Structures was introduced to me, so I started out writing some iterative programs recursively.I found some strange output which shouldn't have come out but if you take a look at these three codes
long factorial(long n)
{
if(n == 1)
{
return 1;
}
else
{
result = n*factorial(n-1);
[Code] ....
These are three versions of the code, achieving the same objective of obtaining a given number and returning the factorial, but in spite of the changes made to the code, they produce the same result. I needed a reason as to why it is so? I tried to dry run all the codes but at some point or the other I got confused, and had to start all over again and couldn't come up with a proper result.
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Dec 2, 2014
So basically i have to read from a text file and get some information back from that and print to screen. Im quite confused and im not sure what loop i should use first to scan the text and receive certain information back?
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Dec 27, 2014
1)A factorial of a number X is equal to X*(X-1)*(X-2)*...*1.For example,3! is equal 3*2*1=6.Create a class called Factorial Algorithm which will compute and print the factorial of an integer number on the screen
2)Write a Java program to accept eight integers and a search element from the user and display whether the element is found or not.(Hint:use bubble sorting and binary search)
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Sep 8, 2014
I am writing a program in Java where a user adds 1 stamp on a letter for every five sheets of paper in it (or fraction thereof)For example, I if I have 11 sheets of paper, I add 3 stamps. If the total number of stamps is more than 3, they don't send it.
I need to ask the user how many sheets of paper they have, and then calculate the appropriate number of stamps based on the formula above. I just don't know how to write the math formula to calculate this, i'm stuck. So far I have:
package test;
import java.util.Scanner;
public class LetterMailing {
public static void main(String[] args) {
Scanner stdIn = new Scanner(System.in);
int numSheets;
[Code] .....
What should I do next?
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Oct 19, 2014
how to print from bluej onto actual paper? how to do the formatting and configuration etc.
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Oct 23, 2014
Writing a program to take input from user. This input must be done with numbers only. If the input is a string I would like the program to loop and ask for input again.
double depositCheckingAmount;
do
{
System.out.println("Please insert amount to deposit into checking.");
[Code]....
As you can see my attempt is to use the ! expresssion incase the input does not equal a double. Is there another method I should be using?
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Sep 22, 2013
So i was assigned to write a program that would print the answer to the system of two linear equation. the form of ax+by=c and dx+ey=f..I wrote this program, but it is incorrect since I tried it out on my terminal and I keep getting incorrect values.
import java.util.Scanner;
public class Quest4 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
[code]....
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Feb 8, 2014
I'm writing a program to dynamically update an xml file to add, delete, and edit entries in the file. I've run into an issue with the add method because when I write into the file, a random letter is added before the line. EX:
I want to add "<item> ..." to the end of the list of entries, but when it is added, this is what is added "Z <item> ..."The spacing for the <item> is correct, however, I don't see where or why the Z is added.
public static void insertItem(Item i)
{
try {
String insert = " <item>";
String text = "";
Scanner in = new Scanner(file);
[code]....
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May 2, 2014
Im trying to write a java program to search nearby bluetooth devices.. Im using Bluecove-glp-2.1.0 and bluecove 2.1.0..Im working on Ubuntu 13.04 LTS.I typend a code to get the local Device name..
public class BluetoothSearch {
public static void main(String[] args) {
LocalDevice ld= null ;
String name = ld.getBluetoothAddress();
System.out.print(name);
}
}
this is my code.. It returns me null. doesn't return me the local Device.
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Apr 3, 2015
I'm in the process of writing a program that determines if a number is a Palindrome or not. I'm not allowed to use strings and am required to use the getSize method shown below. I believe my issue that I'm having is that the "num" is not being called in the getSize method, and therefore not running the while loop, or at least that is what I believe is the issue.
import javax.swing.*;
public class getSize{
public static void main( String[] args )
{
int num;
num = Integer.parseInt (JOptionPane.showInputDialog ( "Please input a number" ));
[code]....
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Nov 4, 2014
User-defined classes. The concept of getters and setters goes right over my head. Right now we're to write a program to test the Person class below. We have to create 2 instances of the class to test each constructor, and test each method.
class Person {
// Data Members
private String name; // The name of this person
private int age; // The age of this person
private char gender; // The gender of this person
// Default constructor
public Person() {
this("Not Given", 0, 'U');
[code]....
then my output will print out the name. But the assignment doesn't tell us to modify the Person class at all, just to create a tester one.
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Nov 26, 2014
I need to convert a .txt file to html text, where the first line is changed to have < h1 > < /h1 > around it and the rest is wrapped in < p > < /p > so for example I read a .txt file that says:
chapter 1
this is a sentence
it would output:
<h1>chapter 1</h1>
<p>this is a sentence</p>
here is what I have so far and I cannot get anything to output.
FileInputStream filestream;
BufferedReader reader;
FileOutputStream output;
String firstline;
String body = "<p>";
String line;
[Code] ......
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Sep 13, 2014
The manager of a football stadium wants you to write a program that calculates the total ticket sales after each game. There are four types of tickets: box, sideline, premium, and general admission. After each game, the data is stored in a file in the following format:
ticketPrice numberOfTicketsSold
Sample data might look like:
250 5750
100 28000
50 35750
25 18750
The first line indicates that the box ticket price is $250 and that 5750 tickets were sold at that price.
Your program should input in this data (using Scanner or an input dialog box), then output that data to a message dialog box along with total ticket sales information. Output the total number of tickets sold and the total sale amount. Make your output user-friendly and "pretty". Format your output with two decimal places. Use JOptionPane and the formatting techniques learned in chapter 3 for your output. Example output might be:
5750 Box Tickets sold at $250.00
28000 Sideline Tickets sold at $100.00
35750 Premium Tickets sold at $50.00
18750 General Admission tickets sold at $25.00
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Feb 24, 2014
Java Code:
public class Search
{
public static final int NOT_FOUND = -1;
public static int binarySearch( int [ ] a, int x )
{
int low = 0;
int high = a.length - 1;
int mid;
while ( low <= high )
[Code] ....
I keep getting illegal start of expression at ={-3,10,5,24,45.3,10.5}
It says I have 12 errors and I have tried so many things to fix it and I just don't know what to change to make it work.
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Mar 2, 2014
I'm working on some exercises and I'm having some problems with a method. I want to create a method to calculate the Factorial of an int number. I already wrote code that asks the user to input an int number and it calculates the Factorial, and it works fine
i.e.: if I input 5 it outputs
5! = 120
as it should. Here's the code:
import java.util.Scanner;
public class Factorial1 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int number;
int total = 1;
[Code] ....
Now I want to make a method to re-use this code in other programs and I wrote this program:
public class TestClass {
public static void main(String[] args) {
System.out.print(factorial(5));
}
public static int factorial(int x) {
int total = 0;
[Code] ....
But when I run this program it outputs 0 instead of 120. What is wrong with this code as it compiles just fine but doesn't work as intended.
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Feb 5, 2014
I'm suppose to be doing a factorial of a number within certain constraints (say a number between 5 and 10). I get the factorial easy enough but I'm getting it for every number no matter what I put in.
textio is used instead of scanner for our class.
Java Code:
public class Factorial {
public static void main(String[] args) {
int max = 0;
int x = 0;
long y = 0;
[Code] .....
Ideally I should be able to put in a number outside the range and the program will do nothing until I put a number in with the correct value.
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Jul 10, 2014
I'm (failing at) writing a program that searches an array using binary search, but I can't get it to work.
My code so far is this:
Java Code:
package sorting;
import java.lang.*;
import java.util.*;
public class sorteh {
public static void main(String [] args){
int[] array=new int [20]; //creates new array
for (int x=0;x<array.length;x++){ //populates array
array[x]=x*3+1;
[code]...
I copied what a website did for the sorting part, but if I have low=0 and high=19, wouldn't mid not be an int?
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Sep 19, 2014
Here is the objective of the assignment:
Quote : A bank in your town updates its customers' account at the end of each month. The bank offers two types of accounts: savings and checking. Every customer must maintain a minimum balance. If a customer's balance falls below the minimum, there is a service charge of $10 for savings accounts and $25 for checking accounts. If the balance at the end of the month is at least the minimum balance, the account receives interest as follows:
- Savings accounts receive 4% interest.
- Checking accounts with balances of up to $5000 more than the minimum balance receive 3% interest; otherwise, the interest is 5%.
Write a program that reads a customer's account number (integer), account type (character: s for savings or c for checking), minimum balance that the account should maintain, and the current balance. The program should then output the account number, account type, current balance, and an appropriate message.
Your program should only allow 'c', 'C', 's', or 'S' as valid input, any other character for the account type should result in an error message. Format your monetary output to two decimal places, and use constants for all the above constant values.
Sample output:
Please enter your account number (int), account type (char), minimum balance, and current balance:
46728 S 1000 2700
Account Number: 46728
Account Type: S
You have earned 0.04 interest on your account.
Current Balance: $2808.00
[Code] .....
Invalid account type!
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May 7, 2014
I am new to programming and we are writing a program to make a tic tac toe game utilizing inheritance, client-supplier, arrays, and EventButton. I am still trying to wrap my head around events and inheritance. We are instructed to write 4 classes (a TicTacToeModel, a TicTacToeView, a TicTacToe Controller, and a TicTacToeButton). I got the TicTacToeModel down, but am having trouble with the other classes.
Instructions for View: Write a class that implements the UML class diagram below. The only purpose of this class is to draw a picture of the specified TicTacToeModel. For purposes of this assignment, we understand a ‘theme’ to include such things as the background color of the tic‐tac‐toe board, the shape and color of the X indicator and the shape and color of the O indicator. While you are free to select your own personalized ‘theme’ your TicTacToeComponent must always be proportionally ‘correct’ regardless of the client‐determined width and height of the Component.
Instructions for the Controller: Write a controller that controls the game. There is one human player (the X player) and the computer player (the O player). The name of the class must be TicTacToeController. In a sense, the controller is the game since the controller will
1) create a TicTacToeModel
2) create a TicTacToeView and
3) create a TicTacToeButton (you must write this class following the design pattern covered in class lectures), a label, and text field such that when the button is pushed, the player moves into the cell selected by the text field. After every player move, the computer moves into a randomly selected empty cell. When the game is over, a text message must be displayed somewhere on the screen the gives the status of the game. While you are free to change the appearance of the controller, the basic elements must be provided
These are our instructions for the TicTacToeButton: create a TicTacToeButton (you must write this class following the design pattern covered in class lectures), a label, and text field such that when the button is pushed, the player moves into the cell selected by the text field. After every player move, the computer moves into a randomly selected empty cell. When the game is over, a text message must be displayed somewhere on the screen the gives the status of the game.And this is the code I have thus far for the button:
import java.awt.event.*;
import java.awt.*;
public class TicTacToeButton extends EventButton{
public TicTacToeButton(int x, int y, int w, int h) {
super("Move");
setBounds(x, y, w, h);
[code]....
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Oct 9, 2014
I'm trying to write a program that will output the total number of large,medium,and small pizza along with the average cost of an order. I'm stuck on this error , "Else without if" on line 48 else ...medium.
import java.util.Scanner;
public class PizzaOrder
{
public static void main(String[] args)
{
Scanner input = new Scanner (System.in);
double cost,total, average;
String name,response,size,type;
int count,l,m,s;
[code]....
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Oct 3, 2014
I am attempting to write a program that reads a nonnegative integer and computes and prints its factorial. So far I have: Java Code: import java.util.Scanner;
public class Chapter3point37 {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int nonNegative = 5;
int count=1;
int product=1;
int factor=1;
System.out.println("Input a nonnegative integer: ");
nonNegative = input.nextInt();
[code]...
how I should correctly prompt the user to input the values.
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Oct 5, 2014
Write a program using switch statement to allow users to choose an item of a menu. For example, the menu looks like the following.
File menu
1. Open
2. Close
3. Save
4. Exit
Enter your choice:
If you type 1, then your program should print out "Open is selected" (double quotes not included).
Notice:
(1) Using Scanner to get user choice;
(2) If the number user input is not in {1,2,3,4}, your program should let user know that.
Here's what I have:
public static void main (String[] args) {
int user = 1
switch (1) {
case value: 1
System.out.println ("Open is selected");
[Code] .....
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Jul 20, 2013
So I am trying to write the output of two different java class files to one txt file while the program runs. The file name is determined before the program is ran, through the command prompt as arguments. How can I get the second class file to edit the same txt file without running into compile errors.
For right now I'm just going to send everything that the second file outputs to a message String variable, so that the Main class outputs to the the text file. I still want to learn how to write to the same text file directly from the second class file.
import java.io.*;
public class Test{
public static void main(String[] args) throws IOException{
int x;
//create a new file internally called doc. But externally labelled the user input
File doc = new File(args[0]);
if (doc.exists()){
[Code] .....
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Jun 28, 2014
I'm trying to learn Java and my current project is to write a short program to determine the factorial of a number entered by the user. I haven't looked. There may be a method that will do it, but I want to use a for loop specifically.
What I have compiles just fine. I'm actually pretty thrilled just with that. Here is what I have:
class factorial {
public static void main( String[] args) {
Scanner scan = new Scanner(System.in );
int num;
int product = 1;
[Code] ....
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Oct 17, 2014
i tried everything but its giving me errors. i tried the for loop but its giving me something else.
this is what i have to do Write a recursive method that prints out the data elements of a linked list in reverse order.
Your method should take in as a parameter the head reference to a linked list. Then, write a recursive method that returns a count of the number of elements greater than a given threshold. You may assume that the data elements in the linked lists are ints. The parameters of your method are a reference to the linked list and a int value representing the threshold.
public class recursion3
{
public static void main(String [] args) {
char a [] = {'A', 'B','C','D','E'};
System.out.println(a);
}
public static String reverseString(String s) {
if (s.length() <= 1) {
[code]....
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Nov 1, 2014
I just can't seem to figure it out how to solve this inherently recursive assignment.The task is to check a directory path and read the files within that path; also, if there are more directories within it, we have to go deeper into those directories to read the files within them - if any. What you're looking at is my skeleton of the assignment:
public class SearchingForStrings {
public static void main(String[] args) {
String path = "."; // Default
File sf = new File(path);
String mainDirectory = args[0]; // These two are just
String keyString = args[1]; // command-line arguments
countLinesWithString(sf, mysteriesDirectory, keyString);
[code]....
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