Doubly Linked List Check Palindrome

Oct 29, 2014

I cant figure out something in my code. I have to check whether given doubly linked list is palindrome or not. If it is palindrome it should print 1 , if not -1. My code has no errors but it always prints -1. I tried debugging but first comparisongives always false and function cant reach to else statement.

Are there any logical errors or i cant do right way of comparison?

import java.util.Scanner;
class DLLNode<E> {
protected E element;
protected DLLNode<E> pred, succ;
public DLLNode(E elem, DLLNode<E> pred, DLLNode<E> succ) {
this.element = elem;
this.pred = pred;
this.succ = succ;

[Code] ....

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How To Move Along A Doubly Linked List

Dec 11, 2014

I'm having some trouble with figuring out how to move along a doubly linked list for an assignment. The program is supposed to be a simple board game simulation. Here is what I have so far:

Space.java:

public class Space
{
private String name;
public Space next;
public Space previous;
public Space(String name)
{
this.name = name;

[Code]...

I seem to have been able to get all the other methods working properly, but I am pretty stuck on how to do the movePlayer. Specifically because it is passing an integer, but my objects are of type Space and Boardgame.

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Elements Of Circular Doubly Linked List

Feb 12, 2015

For the program I have to create, I need to be able to work with the elements of a circular doubly linked list to do the following:

Find an element in the list (specified as an argument)
Insert an element after a specified element (specified as an argument)
Delete an element (specified as an argument)
Display the elements in the list

I can insert elements and display the elements, but I can't figure out how to search for an element, insert an element after a specified element, or delete an element.

What I am having trouble with is passing the elements in the list as arguments for searching, deleting, inserting after an element.

public class doublyLinkedList {
private Node pointer;
private Node dLL;
private int count;

[Code] .....

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How To Insert New Item In Doubly Linked List

Oct 26, 2014

How can I insert a new item at the middle of a BookList . I have also got a Book class represting Book objects and a inner class BookNode referencing them.

public void add(Book newBook)
{ BookNode newNode = new BookNode(newBook);
if (firstNode == null){
// no nodes in the list so add newNode at start
firstNode = newNode;
tempNode = newNode ; }

[Code] ....

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Removing A Node From Doubly Linked List

Apr 11, 2014

Im not sure why the nodes are not being deleted. Is a part of my logic wrong?

public void delete(String s) {
Node temp = find(s);
if (temp==null) {
return;
}
Node prevTemp = temp.prev;
Node nextTemp = temp.next;

[Code] .....

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Doubly Linked List - Swapping Two Sub-parts

Oct 30, 2014

I have a couple more (2or3) and I believe I'll be ready to go 8-)This one is about an Army and a list of warriors... for example 1,2,3,4,5,6,7,9,10 .... and the user inputs points for two sequences, for example 1, 5 and 6,10 .... That means I have to take the array from the 1st element, up to the 5th one, and swap it with the elements from 6to10....

The nest list should be:

6 7 8 9 10 1 2 3 4 5

Things to keep in mind: The list will always have at least two warriors. The intervals will never interfere, and will at least contain ONE warrior..

It says: be careful when the intervals are next to each other, and when be careful when an interval starts with the first warrior, or finishes with the last warrior.

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Huge Numbers And Doubly Linked List

Jul 15, 2014

I am trying to create doubly linked list that can hold huge numbers (i.e. 123456789) and add them together. I have seen some examples on how to do this for linked list, but none really for doubly linked list.

Here is my test driver:

public class HugeNumberDriver
{
/**
* Main method with some test code
*/
public static void main(String[] args)
{
// Create a HugeNumber that is 123456789
HugeNumber h1 = new HugeNumber();
for (int i=9; i>=1; i--)

[Code] ....

Output:

h1 is 987654321
h2 is 88888888885555555555
Exception in thread "main" java.lang.NullPointerException
at HugeNumber.<init>(HugeNumber.java:52)
at HugeNumberDriver.main(HugeNumberDriver.java:29)

As you can see the numbers are displayed incorrectly and the rest of the program does not run. I have a feeling that it has to do with my deep copy constructor or my addDigit() method

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Swing/AWT/SWT :: How To Show Doubly Linked List In Table

Nov 15, 2014

I have a doubly linked list and i want to show the data in a table using java gui.

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Dummy Node In Doubly Linked List - Cannot Find Symbol Variable Error

Jun 5, 2012

Im running into some problems with the Java compiler. This is my code:

public class DoublyLinkedList<T> implements SimpleList<T> {
protected Node dummy;
protected int n;
public DoublyLinkedList(){

dummy = new Node();
dummy.next = dummy;
dummy.pre = dummy;

n = 0;

[Code] ....

I want to use a dummy node in my implementation of the Doubly Linked List, so it will be easier to code all the methods I need to write. I keep on getting a problem with line 14 and 15:

dummy.next = dummy;

dummy.pre = dummy;

// cannot find symbol variable next (compiler error)

// cannot find symbol variable pre

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Doubly Linked Lists And Using Java Generics

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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Check If A String Is A Palindrome By Using Stacks

Oct 23, 2014

I'm supposed to use stacks (implemented with an array) to check to see if a string is a palindrome. I've finished all my classes and methods, but I'm getting an ArrayIndexOutOfBoundsException when I try to run my demo program.Here are my classes:

public interface Stack {
// Creates an empty stack
public void initializeStack()
// Returns true if the stack is empty, returns false otherwise
public boolean isEmpty();
// The stack can never be full, so always return false
public boolean isFullStack();

[code]...

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Feb 14, 2014

I have some class called sorted to sort the linked list through the nodes of the list. and other class to test this ability, i made object of the sort class called "list1" and insert the values to the linked list.

If i make other object called "list2" and want to merge those two lists by using method merge in sort class. And wrote code of

list1.merge(list2);

How can the merge method in sort class know the values of list1 that called it as this object is created in other class.

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Oct 5, 2013

So we have an assignment regarding a linked list implementation of a given list interface.

In my list interface, the method contains(T anEntry) is defined.

In the LList implementation, contains is already implemented as part of getting the core methods in.

Now I am being tasked with the following:

Provide a second implementation of the method contains2(T anEntry) that calls a private recursive method

Private boolean contains (T anEntry, Node startNode) that returns whether the list that starts at startNode contains the entry anEntry.

I've written the private recursive method already. That's not an issue (at least not right now).

But what I don't understand is how startNode is supposed to be populated when this private contains method is called from the public contains2 method? contains2 only takes one parameter: anEntry. the private method takes two parameters: anEntry and startNode. How am i supposed to provide startNode when I am calling contains2?

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Oct 6, 2014

I have this ListInterface class that has operations for my linked list and a LList class. The Llist and ListInterface classes are perfect. My job is to create a driver, or a demo class that showcases these operations. That being said, heres the driver so far:

import java.util.*;
public abstract class DriverWilson implements ListInterface
{
public static void main(String[] args)
{

LList a = new LList();

[code]....

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Mar 21, 2014

What I'm supposed to do is make a method to insert a set of Tiles to the list,i.e.,a detour(make sure that the inserted detouris compatible with thecurrent path so that the resultingpathdoesnot have any gaps). But I'm confused on how to go about doing it. I was thinking of maybe just adding 1 to the current Node.

import java.io.File;
import java.io.FileNotFoundException;
import java.util.List;
import java.util.Scanner;
public class Path {
static Tile startTile;

[code].....

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Jan 30, 2014

I'm trying to implement an Office class that contains an inner class: WorkerNode. The WorkerNode class has a name attribute (String) and WorkerNode attributes for boss, peer and subordinate. The attributes of Office are manager and current which are WorkerNode references. The manager refers to the entry point of the structure and current is the current node in the structure. For simplicity, i'm going to try to limit it to 3 levels and assume that the names are unique. I've put together a Office class that containing main and provided the code I've worked on so far.

public class Office {
public static void main(String[] args) {
String name=Input.getString("input the manager's name: ");
Office office=new Office(name);
int option;

[code]....

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Apr 20, 2014

I have made a node class and im trying to implement a sorting method. I must use a selection sort but with specific instructions: "Your method should not need to use the new operator since it is just moving nodes from one list to another( not creating new nodes)

this is my current implementation ..but i am instantiating new object..

public class NodeInt
{
private int data;
private NodeInt next = null;
public NodeInt(){}
//precondition:
//postcondition:
public NodeInt(int data, NodeInt next)
{
this.data = data;
this.next = next;

[code]....

edit: this is the part that worked but i had it commented out so i have the previous and current declared above but didnt copy.

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Apr 30, 2014

Ok here I have a code that generates 1 million random values then converts them to a string then hashcode. I then insert into a linked list and then I want to run through each hash and find it in the linked list timing each run then averaging out the time at the end.

It works great for smaller amounts of numbers it is searching for (fine under 50 thousand searches for the for loop starting at line 24 LinkedListTest.java) but when I try to do the full million searches it gives me "a Exception in thread "main" java.lang.StackOverflowError" at line 158 in List.java. Maybe im getting tired but I cannot figure out why.

// class to represent one node in a list
class ListNode< T >
{
// package access members; List can access these directly
T data; // data for this node
ListNode< T > nextNode; // reference to the next node in the list

[code]....

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Building Linked List Whose Nodes Data Is The Sum Of Nodes Of Other List

May 1, 2014

public void add(int d){
listNode l = new listNode (d, null);
l.next = first;
first= l;

public list Sum2List (list l1, list l2){
//variables
int sum;

[Code] .....

But I have a problem in my first listNode where it ll be pointing to null, thus in the sum2List method the program checks the while condition into false and doesn't go through the loop.

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Add Or Remove Will Be More Efficient By A Linked List

Jan 31, 2015

if one address point on another address. so set and get methods will be less efficient then an array, but add or remove will be more efficient by a linked list ? a linked list also inherit from queue so if i add an elemnt via "addFirst" function . where its adding the element ? to the right most or left most ?
if i have for example :

here [ ] --> [ ] --> [ ] --> [ ] -->[ ] or here

linked list its FIFO so the head will be the right most ?

Edit : its confused me a little bit but i understood now .so it will be at the left most. its actually ordered . not like the stack which is LIFO.

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Oct 30, 2014

I searched a lot but can't seem to understand the sorting of a SLLNode... I noticed a method called Bubble Sort, I understand how it works, but can't think of a way to implement it to my code..

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Dec 30, 2014

Is there a particular implementation of a linked list you are referring to in your question?

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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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Feb 17, 2015

I'm trying to print the contents of my linked list. I'm using nodes and within those nodes it hold String data. So i want to print out the data within the nodes. Whenever i do

System.out.println(node1.data),

it prints perfectly. But i'm trying to use a method where it would loop through the list and print out the data for every node in it. when i run my print method i get results such as

Node@15db9742
Node@6d06d69c
Node@7852e922.

Here is my print method i created

Java Code:

public void print(){
Node<E> current = head;
while (current.next != null){
System.out.println(current.data);
current = current.next;
}
} mh_sh_highlight_all('java');

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Apr 12, 2014

I am creating a recursive method to reverse a linked list in java. It works the first time when I call it, but I want it to work where I call it a second time and it reverses it to the original state. How can I get that to work with this implementation?

public void reverseList() {
System.out.printf("%-16s%-3s%n", "Name", "Score");
System.out.println("--------------- -----");
reverseList(first);
} public void reverseList(Node aNode) {
if (aNode != null) {
reverseList(aNode.next);
System.out.printf("%-15s%6s%n" , aNode.name , aNode.score);
}
}

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How To Advance To Next Node In Linked List

Apr 7, 2014

I am trying to advance to the next node in my linkedList. Below is what i have so far.

/**
* Move forward, so that the current element is now the next element in this sequence.
* @param - none
* @precondition:
* isCurrent() returns true.
* @postcondition:
* If the current element was already the end element of this sequence (with nothing after it), then there is no longer any current element.
* Otherwise, the new element is the element immediately after the original current element.
* @exception IllegalStateException
* Indicates that there is no current element, so advance may not be called.
**/

public void advance( ) {
// student implements
if(!isCurrent())
throw new IllegalStateException();
else{
while(cursor != null){
precursor = cursor;
cursor = cursor.getLink();
}
}
}

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