Big-O Involving Arrays And Linked Lists When Using PriorityQueue
Oct 25, 2014
I'm not sure if my understanding of PriorityQueues is correct, so I'm trying to check if my reasoning is valid. I'm supposed to compare the Big-O for arrays and linked lists for the following instructions:
Insert 100 objects having the priorities 1, 2, 3, ... , 99, 100
Big-O for Array: __________
Big-O for Linked List: ___________
Insert 100 objects having the priorities 100, 99, 98, ... , 2, 1
Big-O for Array: __________
Big-O for Linked List(Assume no tail reference): ___________
If my understanding is correct, priority queues take in items randomly with no particular order, but they are removed according to the priority of each element. If what I've said is true, wouldn't that mean that inserting any number of objects would be O(1) for both linked lists and arrays? If the PriorityQueue has no particular order, then wouldnt each add() simply insert something to the next array index/linked list node?
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Mar 2, 2015
public class School {
public final int MIN_GRADE = 0;
public final int MAX_GRADE = 100;
private int [] grades;
public School( int students ) {
grades = new int[students];
[Code] ....
The output is :
The numbers in the array are: 1 2 3 4 6 7 8 9 10 13 14 15
The highest grade is: 11
For some reason it is not giving me the highest number in my array. Did I write the method wrong ? Is my array even passing through HighestGrade ?
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Nov 27, 2014
I currently don't understand how the node's work.
private static class Node<AnyType>
{
private AnyType data;
private Node<AnyType> next;
public Node(AnyType data, Node<AnyType> next)
{
this.data = data;
this.next = next;
}
}
Why do I make private Node<AnyType> next;And why do I have an inner class of Node for a linked list?I had the same topic in C, but there it was somehow easier than in java. Because there you have pointers.
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Apr 27, 2014
Write a Java function Sum2List that takes two lists L1 and L2 of the same size and returns list L that contains the sum of data inside the corresponding nodes of lists L1 and L2.
ex: L1 = {1,2,3}
L2 = {4,5,6}
L = {5,7,9}
I do not know how to iterate through two different lists >>
public LinkedList Sum2List(LinkedList l1, LinkedList l2){
LinkedList l3 = new LinkedList();
ListNode Current1 = L1.getFront();
ListNode Current2 = L2.getFront();
while(Current1 != null){
l3.Add(Current1.getItem() + Current2.getItem());
[Code] .....
This my attempt to write the code , but the dr. side that we have not to use the build in methods ( getNext()...etc)
in the function .
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Mar 10, 2014
I have an XML sheet and my project is top retrieve the required elements from XML sheet. So my format of XML was like follows:
<Class>
<Employees>
<EMPLOYEE>
<ENum> Abc123</ENum>
<Ename> John<?Ename>
<EType>Mathematics</EType>
[Code] ....
I have used unmarshalling concept to retrieve the data elements... I have to check whether the elements satisfy few regulations when compared with data in Database. So, i thought of grouping the employees depending on EType. I have created a Map with linkedlist of employees. Say Map<String, LinkedList<Employe>>EmpMap=new Map<String, LinkedList<Employe>>();
I have already created a class named Employee which has all the setter and getter methods for employee.
Here am going to take Etype(Employee type) as key and linkedlist(list of employees of certain type) as value. How to iterate these linked lists and place them in my Map.
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Jul 19, 2014
Why is this method throwing a null pointer exception when I call it from main?
I'm trying to submit an integer to indicate the number of nodes in a linked list to delete and then delete them headfirst.
public boolean delete(int x){
if (x > count || head == null){
return false;
}else{ while (x>0){
head = head.getPrevious();
[Code] ....
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Feb 13, 2014
I have the following code that supposed to perfrom sorting on the linked list using method sort in order usind node concept of Linked List but seems to give inlogic results. the following code tests only the values lower than the first value but i can't manage to sort the data higher than the first entered value;
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
import java.util.*;
public class ListNode<T extends Comparable> {
ListNode<T> nextNode;
T data;
public ListNode(T item)
[Code] .....
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Oct 25, 2014
I'm working with Doubly Linked Lists and using Java Generics..
My nodes looks like this:
class DNode<E> {
DNode<E> previous;
DNode<E> next;
E element;
//and all methods inside
}
My list of Nodes looks like this:
class DLL<E>{
private DNode<E> head;
private DNode<E> tail;
private int size;
[code]....
As you can see, as arguments they get "E o"...I need to write a program, which from the main function asks the users how long is the list, and after they type it's length, I ask them to start typing the elements (integers)...and this is how my main method is written, but I can't seem to make it work, specialy when I call the "insLast" method,I guess it's because the arguments i'm giving to the function...how to read the elements and write them into the list?
public static void main(String[] args) throws IOException {
DLL<Integer> lista=new DLL<Integer>();
BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
String s = stdin.readLine();
int N = Integer.parseInt(s);
s = stdin.readLine();
String[] pomniza = s.split(" ");
for (int i = 0; i < N; i++) {
lista.instLast(Integer.parseInt(pomniza[i]));
}
}
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Apr 16, 2014
I am creating a chained hash table that uses my own LinkedListclass to handle collisons. Here is where my issue is occuring: I start with an array of LinkedLists, my "hash table", intially set to null. When i wish to add a word, if the desired location is null, I create a new LinkedList, place it in that array index. I then create a new LinkedListNode and set the head of the new LinkedList to the new node.
My issue is occuring here: Whenever I set the head of my new LinkedList to my new LinkedListNode all of my previously created linkedlists also have their head changed to the new node.
My debugger shows that I am truly creating new linkedlists every time. I was afraid each array index was just pointing to a single array, but that is evidently not the issue. Below is all the relevant code
public class SetOfStrings {
private int arraySize;
private LinkedList[] mainArray;
private int totalCount;
//other methods here
public boolean add(String toAdd) {
int hashToAdd = hash(toAdd);
[code]....
SUMMARY: Whenever I set the head of a Linked List to a new node, it changes the head of all my linked lists to point to the same new node
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Oct 29, 2014
Basically, the program is to be able to read information from a file like this;
11111 63.5
22222 59.9
33333 82.4
44444 73.1
55555 77.3
66666 99.5
77777 68.7
88888 53.2
99999 66.8
where the first number is student number and the second is their grade. I need to read this information from a .txt file and dynamically create a new node containing that student's number and mark, and insert it in the correct position in the linked list (in descending order based on grade). So I get that each Node needs to contain two data types, an Int for Student # and a Double for their grade, and I'm pretty sure I've done it correctly with my StudentNode class which can be found in the source code linked above.
But what I don't get it using that class to create Nodes in my main class and then sort them based on their Double grade value WHILE they are being sorted. I just don't understand where to actually put the methods and such that does these things. Apparently I'm supposed to have three classes.
One named StudentNode which is just the node info, which I have done.
The second is called StudentList which is apparently supposed to contain the head of LinkedList and the methods I need? I'm not sure how it ties into StudentNode though.
The third and final is just the main class which I'll use to test it.
Then after all that I need to print out the median mark through a recursive method that isn't allowed to use any loops or call and functions/methods that use loops. The function should return the node in the list which contains the median mark. Secondly, in order to find the median, you need to know how many items in total are in the list. Your recursive function must calculate that number (also recursively); you may not keep track of this count elsewhere your program. Your recursive solution should only examine each node only once, and the depth of the recursion should be equal to the number of nodes in the list.
Here's my current in-progress code.
import java.io.FileNotFoundException;
import java.util.Scanner;
class StudentNode {
private int studentNum;
private double grade;
private StudentNode next;
[Code] .....
I'm pretty sure the StudentNode class is fine, it's the StudentList class that I'm not sure about. I'm not sure how to add nodes since there isn't a getNext() method in the StudentList class.
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May 6, 2015
I am trying to implement product method below which returns the set representing the Cartesian product of the current set and a given set (the Cartesian product contains all ordered pairs (a, b) where a belongs to the current set, and b belongs to the given set). The product should be a ListSet <Tuple<E>> object where each ordered pair is a Tuple element. (I have a Tuple class which implements an ordered tuple)
What am I trying to do in the product method : Make 2 for loop and inside the for loop make an array of <E> then set the 2 elements of the tuple then again set tuple and add it to arrayList. how to set 2 elements of the tuple and set tuple ??
public class ListSet<E> implements Iterable<E>{
SinglyLinkedList<E> sl;
public ListSet(){
sl = new SinglyLinkedList<E>();
[code]....
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Oct 9, 2014
I am trying to write a code that allows you to input 2 lists and it tells you if they are identical or not. However, when I enter my fist list I can only enter two values and then it asks for the next list. How would I fix this to allow me to enter more than two values?
Also, If the second list is different it has me enter more values that list one.
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
// Enter values for list1
System.out.print("Enter list1: ");
int size1 = input.nextInt();
int[] list1 = new int[size1];
for (int i = 0; i < list1.length; i++)
list1[i] = input.nextInt();
// Enter values for list2
System.out.print("Enter list 2: ");
[code]...
My output looks like this:
Enter list1: 1
2
Enter list 2: 2
3
2
Two lists are not identical
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Jan 15, 2015
The assignment is to: Use arrays to create an applet that lists five of your favorite songs.
The applet should scroll the list of song titles, one at a timeeach song title should start at the top of the applet and scroll to the middle then, scroll off the right hand sideeach new song title should scroll in a different colourthe applet should loop, that is, when it gets to the end of the list, start over again at the beginning of the list
I already have it looping the text with different colors. It's just they all loop at the same time. How to loop them separately. How to switch the program to where the strings will change with content and color on each loop that would work too.
Here is the code I got so far:
import java.awt.*;
import java.applet.Applet;
public class FavouriteSongs extends Applet implements Runnable
{
String[] Songs = {"Travelling Man-Chameleon Circuit", "Sing-Ed Sheeran", "It's Time-Imagine Dragons", "I See Fire-Ed Sheeran", "Colder Weather- Zac Brown Band"};
int yPos = 0, xPos = 50;
Thread runner;
[Code] .....
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Nov 2, 2014
How to go through each link item in both lists, and directly link them into the new list in order without using insert()
class Link {
public long dData; // data item
public Link next; // next link in list
// -------------------------------------------------------------
public Link(long dd) // constructor
{ dData = dd; }
// -------------------------------------------------------------
public void displayLink() // display this link
{ System.out.print(dData + " "); }
} // end class Link
[Code] ......
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Oct 9, 2014
My instructions are to:
1. Prompt the user to input two positive integers: firstNum and secondNum (firstNum must be smaller than secondNum).
2. Output all the even numbers between firstNum and secondNum inclusive.
3. Output the sum of all the even numbers between firstNum and secondNum inclusive.
4. Output all the odd numbers between firstNum and secondNum inclusive.
5. Output the sum of all the odd numbers between firstNum and secondNum inclusive.
*Use while loop
int firstNum, secondNum;
Scanner keyboard = new Scanner(System.in);
System.out.println("Enter an integer: ");
firstNum = keyboard.nextInt();
[Code] ....
What to do with the while loop and how to find even and odd numbers.
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Jan 29, 2015
As a result I need to get 6 66 666 6666 66666, but I'm getting a mistake. Can anb explain what's wrong?
Java Code:
public static void main(String [] args)
{
int[] sixes = new int [6];
for (int i = 0; i < sixes.length; i++)
{
sixes[i] = i * 10 + 6;
System.out.print(sixes[i]);
}
} mh_sh_highlight_all('java');
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Jan 31, 2014
I have created a text file that contains a small list of toy names and prices, like:
Barbie, 12.95
Lego, 15.99
Hot Wheels, 5.00
Power Rangers, 6.49
And what I would like is my application to read the contents of the file and store the toy names in a list component. And then I want to be able to select a toy name from the list and add it to a shopping cart that is a list component as well. I want to the application to have menu items and buttons to allow me to remove items from the shopping cart, clear the shopping cart of all selections, and check out.
When I check out, the application should calculate and display the subtotal of all the toy names in the shopping cart, the sales tax (which can just be 8 percent of the subtotal), and the total. create this simple application example I've just made up, and I'm going to add and use this example to create a bigger application myself.
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Oct 23, 2014
Alright so I'm trying to write a code that implements a for loop and if statements that displays any number from 100-200 if the number is divisible by either 5 or 6 in rows of ten numbers each row. If it is not divisible by that number then it should go back to the beginning of the loop until it reaches 200. My main problem is that it doesn't display anything. I don't get any errors or anything but every time I run the program it just displays nothing. Sample output is at the bottom of the code.
public class Exercise5_11 {
public static void main(String[] args) {
int count = 0;
int i = 100;
//for (the numbers from 100 to 200)
for (i = 100; i>100 && i<200; i++){
[Code] ....
/*Output
100 102 105 108 110 114 115 125 126 130
132 135 138 140 144 145 155 156 160 162
165 168 170 174 175 185 186 190 192 195
198 200
*/
It is still wip of course so I was trying to just get it to display int i but it doesn't do anything and I'm not really sure why.
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May 14, 2014
So I want the method getDisplayText of d to be returned as long as the for loop runs. When I do this I get a compile time error to enter a return statement. I am currently trying to fix it by returning an empty string, yet this doesn't seem the right way to go.
public static String displayMultiple(Displayable d, int count)
{
for(int i = 1; i <= count; i++)
return d.getDisplayText();
return "";
}
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Nov 26, 2014
I'm working on a project that involves the following:
-Creating a superclass of bankaccounts
-Creating two subclasses, checkingaccount and savingaccount
-Each of the two subclasses has different methods (writeCheck for checking, for example)
-Both types are created in a main class bank and stored in the same array
So let's say a user goes through the menus and creates a few savingAccounts and a few checkingAccounts (stored in the accounts[] array). Then, to write a check from one account, the user can enter the account number (a string), and the method will use a for loop to cycle through the array until it hits an account number match. Then it checks that it's the correct account type and calls methods from the subclass.
Problem here is that some methods work and some don't. In the following example:
for (BankAccount account: accounts) {
if (account.getAccountType().equals("Checking")) {
do {
if (account.getAccountNumber().equals(accountNumber)) {
amount = Double.parseDouble(JOptionPane.showInputDialog(
[Code] .....
The getAccountNumber method works but writeCheck is throwing an error. I tried creating a method in the superclass and overriding it in the subclasses but with no success.
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Feb 1, 2014
I am learning Java on my own and I am taking on very small project by myself for fun, and I'm just stuck on this small part of the project.
So I have created a text file that contains a small list of toy names and prices, like:
Barbie, 12.95
Lego, 15.99
Hot Wheels, 5.00
Power Rangers, 6.49
And what I would like is my application to read the contents of the file and store the toy names in a list component. And then I want to be able to select a toy name from the list and add it to a shopping cart that is a list component as well. I want to the application to have menu items and buttons to allow me to remove items from the shopping cart, clear the shopping cart of all selections, and check out. When I check out, the application should calculate and display the subtotal of all the toy names in the shopping cart, the sales tax (which can just be 8 percent of the subtotal), and the total.
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Apr 4, 2014
1. Modify the following class so that the two instance variables are private, there is a constructor that accepts both the player's name and sport and there are get and a set methods for each instance variable:
public class Player {
String name;
String sport;
}
2. You can pass an instance of this class to the JLabel constructor if you want to display text in the label.Select one:
a. myLabel
b. myText
c. String
d. JTextField
e. JLabelText
how to start making this work?cause i am not familiar with the terms here and want to complete this program and I am new to java programming?
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Jan 25, 2014
I'm writing a program for exemplary reasons that is basically two text fields, one for a username, and one for a password. the way its written is asking testing for what is inputed into the text fields if its equal to a "valid" username and password. if it is, a variable representing that is set equal to 1. there is another if statement asking if the actionevent.getsource is equal to the name of the textfield. the issue I had was that when I ran the program, it seemed to only test for the first condition, so I got the same result from the program regardless of what I input into the text field.
The Code
Main class:
import javax.swing.JFrame;
public class Alpha {
public static void main(String args[]){
log l = new log();
l.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
l.setSize(360, 240);
l.setVisible(true);
[Code] .....
The code originaly was written "eve.getSource() ==" but I changed that to see if it would resolve the issue with no avail. With it written this way, the program does nothing upon entering the text and pressing enter. Currently, there is nothing written to change the variable "val" to 1 to show that the username is valid. I did this because I can't figure out how I would go about doing this.
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Jun 28, 2014
I mainly would like to know is a int[4][4] or a int [4*4] is more efficient to use. Which takes more storage? Which requires more to process? that kind of stuff.
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Jun 16, 2014
I need to convert units accurately. Some of these units include angstroms (0.1nm) and astronomical units or light years. I can't seem to accurately perform these equations (probably mostly because of lack of a proper conversion formula). For example:
1 angstrom = 1.79985601 × 10^-14 leagues (or, 0.00000000000001799856 leagues).
To perform the conversion right now, I'm simply multiplying the angstroms by 0.00000000000001799856. However, inputting 55560000000000 (angstroms in one league) results in 0.9999999936. Why is this? Is it possible to work around it? I believe there's a term for the inability for a computer to process 1/3rd properly, but I can't remember what it's called - is that the problem?
I am using BigDecimals for all equations.
Edit: a mod can change the title if they think another is more fitting.
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Aug 6, 2014
public void myFunc(MyNode n, ArrayList<MyNode> path) {
boolean hasChildren = false;
path.add(n);
int index = path.indexOf(n);
ArrayList<MyNode> statefulPath = new ArrayList<MyNode>();
[Code] ....
I have similar code that I stepped through in a debugger. After running the code I found that it built the desired tree, in this case a root node H with left child L and right child P. I want list of lists to contain all paths from root to leaf. I expected [H, L] and [H, P]. I discovered that statefulPath is not stateful; after a recursive stack frame pops, statefulPath still contains n! But that stack frame just popped! I expected to see statefulPath be [H] in the debugger and it was [H, L]! So I later have a list [H,L,P] which I don't want. How do I make the statefulPath list I want for my algorithm?
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