Sorting Linked Lists Via Consecutive Nodes
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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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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Apr 30, 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.
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Feb 5, 2014
A Employee Class where i want to sort there lists one by there salary and one by there name individually as per the requirement ? How we do it?
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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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Mar 9, 2014
TL,DR: observe the nodes just below, that is the data each node in the link list contains. How do I iterate through the entire list to reach the last element (H), so I can add an element right after it?
So I have 4 nodes doubly linked with two dummy nodes for head and tail:
head
node1 = {A}
node2 = {null, B}
node3 = {C, null, D, E}
node4 = {null, F, null, G, null, null, H, null}
tail
Ok, so since the list only contains 8 elements that are not null, its size is actually 8 correct? So now lets say I have an add method that has
add(E item) and inserts the item at the end of the list. So I can get to the last node with tail.previous(), but then how do I iterate to the end so I can add the item after the last item in the list (H). I guess I don't know how you only access one nodes data when that data is an array with empty spaces.
Here is the entire Node code:
Also, I can't just iterate through the whole thing because I am not supposed to. I am supposed to just find the right node and iterate through that only.how to maneuver around a linked list containing nodes where each node contains an array.
/**
* Node class that makes up a DoublingList. Feel free to add methods /
* constructors / variables you might find useful in here.
*/
public class Node<E> {
/**
* The node that comes after this one in the list
[code]....
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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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Apr 19, 2015
I'm working on an assignment that asks for the user to input 2 lists of numbers and my program will merge and sort the lists using arrays and 2 methods. I think I have most of it down, but I'm not sure how to go about getting the user inputs. In my current code, it's giving me a bunch of 0s instead of a sorted list.
import java.util.Scanner;
public class merge2sortedlists {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
[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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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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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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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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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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Sep 12, 2014
I wrote displayAscending() and displayDescending() methods to this double linked list and it is not working at all. Logically it seems fine to me. I positioned the head in the beginning in the ascending method; created a variable named data1 as an auxiliar variable so it can store the values that are going to be moved; and moved the values. Same thing for the descending method but instead of the head I put the tail and move left the list, instead of right.
import java.util.*;
class node {
int data;
node left;
node right;
node(int d, node l, node r) {
data = d;
[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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Feb 23, 2014
im trying to do a program to find if numbers are consecutive or not! if they are consecutive i need a true as a return and a false when they are not... i did this program and im sure i did something wrong because i keep only true returns ..
Example: (3,5,7) (1,2,2) (7,7,9) should return a false!
Java Code: import java.util.*;
public class Consecutive{
public static void main (String [] args){
Scanner console= new Scanner(System.in);
System.out.println("Enter three numbers");
String numbers = console.nextLine();
System.out.println( "The numbers (" + numbers + ") is '" + consecutive( numbers ) + "'" );
}//end of main
[code]...
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Mar 24, 2014
I don't remember where but I faintly recall one of the oracle docs examples (dealing with GUI basics I think) having something similar to
button.add(lbl).addIcon().addActionListener(al);
but only in the aspect of using .method.method.method
The reason I'm asking is because I want to shorten this
int j = 0;
for(int i = 0; i <= 6; i+=3){
pnl[j+2].add(lbl[i+5]);
pnl[j+2].add(lbl[i+6]);
pnl[j+2].add(drop[j]);
pnl[j+2].add(lbl[i+7]);
pnl[j+2].add(btn[j]);
j++;
}
Into something like this
int j = 0;
for(int i = 0; i <= 6; i+=3){
pnl[j+2].add(lbl[i+5])
.add(lbl[i+6])
.add(drop[j])
.add(lbl[i+7])
.add(btn[j]);
j++;
}
I might be way off though... but I'm just wondering under what circumstances would this be possible
When I try it in Eclipse a little notification appears that says...
"The method add(PopupMenu) in the type Component is not applicable for the arguments (JLabel)"
When I google 'Component' I see it appears to have something to do with Serialization (which I'll need to look into)
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Feb 26, 2015
I wanted to know if I was off to the right start. I am trying to write a program using the for loop the calculate the product of the consecutive numbers 4 through 8 but so for I am getting 3 values output and I only want 1 value at the print out.
The code I am using outputs the numbers too large. I am trying to see where I went wrong.
for ( int i = 4 ; i <= 8; i++)
{
int j = i++;
int k = j++;
int l = k++;
int m = l++;
System.out.println( + (i*j*k*l*m) );
}
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Feb 21, 2014
I need to find if the number entered by the user are consecutive or not!
Ex:this should return a true!! This should return false!
(1,2,3) (3,5,7)
(3,2,4) (1,2,2)
(-10,-8,-9) (7,7,9)
My program seems to work ok when i enter number in order like 1,2,3 = true , and all the numbers for false seem to be working as well! my problem is when i enter number like 3,2,4 that are not in order but still are consecutive!! I thought that another if statement would be the solution but i have tray several different ones and still can't make it work !!!
Java Code:
import java.util.*;
public class Consecutive{
public static void main (String [] args){
Scanner console= new Scanner(System.in);
System.out.println("Enter three numbers");
String numbers = console.nextLine();
[[Code] .....
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Nov 9, 2014
if I want to add a number of X consecutive values in an array and get the minimal total value along with the indexes that caused this result, how can I do that? for example:
X = 2
array[4] = (5,2,8,6,7)
start adding every 2 consecutive values as following:
array[0]+array[1] = 5+2 = 7 //minimal value
array[1]+array[2] = 2+8=10
array[2]+array[3] = 8+6= 14
array[3]+array[4] = 6+7=13
output:
minimal value = 7
indexes of minimal values are: 0 and 1
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Nov 9, 2014
Here is my problem: if I want to add a number of X consecutive values in an array and get the minimal total value along with the indexes that caused this result, how can I do that?
For example:
X = 2
array[4] = (5,2,8,6,7)
start adding every 2 consecutive values as following:
array[0]+array[1] = 5+2 = 7 //minimal value
array[1]+array[2] = 2+8=10
array[2]+array[3] = 8+6= 14
array[3]+array[4] = 6+7=13
output:
minimal value = 7
indexes of minimal values are: 0 and 1
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Aug 16, 2014
I have the following program. In a nutshell, I creates an array of 3 consecutive ints and the user has to guess what those numbers are, knowing that they are between 0 and 7, this is from Head First Java. In the book, the code has a bug that is made on purpose and they challenge you to fix it. As you can see bellow, every time a user's guess matches a int in the array, the NumOfHits is increased by one. When the NumOfHits is 3 (the length of the array) the game finishes.
The bug is that if you guess 1 and 1 is in the array, if you type in 1, 3 times, I will increase the NumOfHits 3 times and end the game as if you had won. To solve the bug, you need to find a way to tell the program that if the user already guessed that number, it should no longer be taken into account and we shouldn't increase the NumOfHits if the same number is provided.
I "fixed" this by searching for the index of the number that matches an int of the array, and changing that index's value to 100, since the user knows that the numbers are between 0 and 7, they will not submit 100.
The result? If the user submits 2 and 2 is in the array, the value of its indexed is replaced by 100, so that if the user submits 2 again it doesn't count as a match.
Please see the comments in the code
import java.io.*;
import java.util.Arrays;
class DotCom{
int NumOfHits = 0;
int[] LocationCells;
public void setLocationCells(int[] locs){
LocationCells = locs;
[Code] .....
The code works, but for some reason, some times I get a ArrayIndexOutOfBoundsException run time error and it appears to be somehow random. This is what I saw on the command line earlier
C:Userspablo.alvarez>java launchDotCom
Enter a number: 3
missed
Enter a number: 4
hit
Enter a number: 5
hit
Enter a number: 7
missed
Enter a number: 5
missed
Enter a number: 4
missed
Enter a number: 3
missed
Enter a number: 4
missed
Enter a number: 5
missed
Enter a number: 6
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
at DotCom.checkYourSelf(launchDotCom.java:16)
at DotComGame.startGame(launchDotCom.java:59)
at launchDotCom.main(launchDotCom.java:72)
As you can see here, 3 returned 'missed' but 4 and 5 returned hit. Since the numbers are in sequence and are only 3, it makes sense that the last number is 6 (4,5,6). You will then notice that when I submitted 3 and 4 again it returned 'missed' as expected, because the numbers were already matched earlier, but then when I submitted 6, it returned the error seen above.
Sometimes this doesn't happen at all, sometimes it happens at the 2nd guess or third, it appears to be somehow random. I'm familiar with the error message, but I don't see where I'm using an index that doesn't exist in the array. The only time I'm referencing an array index is on
LocationCells[index] = 100;
but the index variable will only hold a value if the int submitted by the user matches on of the values in one of the indexes, so how is it that I'm going over the number of available indexes?
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