doubly linked list

[alikhandro]

how can i implement a polynomial class using the doubly linked list data structure such that each node of the list holds the coeffient and the exponent of the term ?

[NormR1]

Define a Node class with the required variables.

[alikhandro]

thanks alote

[NormR1]

If you are having problems with your code, post it and ask some specific questions.

[alikhandro]

         public void extract(Object obj)
//       {
//           Element element = head;
//           while ((element != null) && (!element.data.equals(obj)))
//           {
//               element = element.next;
//           }
//
//           if (element == null)
//           {
//               throw new IllegalArgumentException("item not found");
//           }
//           if (element == head)
//           {
//               head = element.next;
//               if (element.next != null)
//               {
//                   element.next.previous = null;
//               }
//           }
//           else
//           {
//               element.previous.next = element.next;
//               if (element.next != null)
//               {
//                   element.next.previous = element.previous;
//               }
//           }
//           if (element == tail)
//           {
//               tail = element.previous;
//           }
//       }
`

this is the first time i work with doubly linked lists.
how is the element is delete if its found in the list? knowing that it is not a head or a tail ?
thanks in advanced

[NormR1]

It best to use a piece of paper to draw out how the nodes in a linked list are connected
and to see how to remove a node from the list.

[alikhandro]

i did but couldnt understand how its working with the midle node.in head and tail i discovered how.at least give me a hint :D

[NormR1]

Writing down a linked list on a piece of paper is the only way I know how to do it.
Draw lines that represent the links. When you remove a node, some of the lines must be redrawn.
When a line is redrawn that represents making a change to a node pointer.
Try making a list in pseudo code of how to remove a node in the three places: first, middle and last. There are several pointers that must be changed. If you know how to do the first and last, then only work on the middle node.

[alikhandro]

ok i will try again

[Taywin]

Here are steps if the node is in the middle of the list (not head or tail).

1)Update the point-to next node of its previous node to its next node.
2)Update the point-to previous node of its next node to its previous node.

/*
Assuming nodeX0 is the head.
Removing nodeX4 from the list...

Start condition:
nodeX0 <-> ... <-> nodeX3 <-> nodeX4 <-> nodeX5 <-> ...

Apply #1
nodeX0 <-> ... <-> nodeX3 <- nodeX4 <-> nodeX5 <-> ...
                        |               ^
                        +---------------+

Apply #2
nodeX0 <-> ... <-> nodeX3 <- nodeX4 -> nodeX5 <-> ...
                      ^ |              ^ |
                      | +--------------+ |
                      +------------------+

Ignore the reference to nodeX4 and it will be removed from the memory by GC later on.
*/

Done... In Java, you don't need to manually free up memory or write a deconstructor.

[adesexy]

hi . i need help.You are asked to implement a set of programs to simulate a group of users being logged onto a computer network. Users
may be added, deleted, modified, displayed and searched for at any time. A method to test whether a user’s name is a
palindrome (a string that reads the same from left to right as right to left) should also be included. Finally, a logout feature
should be added that continuously logs out users at random every three seconds. The users should be maintained within a
doubly linked list. You should modify the files supplied with this exercise to create a class for a circular doubly linked list,

[NormR1]

Please start your own thread for your new problem.
Be sure to post the code you are working on and to ask specific questions about the problems you are having.