/*

* (C) 2016 CSE2010 HW #2

*

* Modify and/or methods (fields) if necessary ...

*/

import java.util.*;

class DNode<T> {

private T info;

private DNode<T> next;

private DNode<T> prev;

DNode(T info, DNode<T> prev, DNode<T> next) {

this.info = info;

this.prev = prev;

this.next = next;

}

T getInfo() {

return info;

}

void setInfo(T info) {

this.info = info;

}

DNode<T> getNext() {

return next;

}

void setNext(DNode<T> n) {

next = n;

}

DNode<T> getPrev() {

return prev;

}

void setPrev(DNode<T> p) {

prev = p;

}

}

public class DLinkedList<T> {

private DNode<T> header;

private DNode<T> trailer;

private int size;

public DLinkedList() {

header = new DNode<T>(null, null, null);

trailer = new DNode<T>(null, header, null);

header.setNext(trailer);

size = 0;

}

public boolean isEmpty() {

return size == 0 ? true : false;

}

// Add new node n at the front

public void addFirst(DNode<T> n) {

addAfter(header, n);

}

// Add new node n at the rear

public void addLast(DNode<T> n) {

addBefore(trailer, n);

}

// Remove a node at the front

public void removeFirst() {

remove(header.getNext());

}

// Remove a node at the front

public void removeLast() {

remove(trailer.getPrev());

}

// Add new node n before node p

public void addBefore(DNode<T> p, DNode<T> n) {

DNode<T> pp = p.getPrev();

pp.setNext(n);

p.setPrev(n);

n.setNext(p);

n.setPrev(pp);

/*

* Your code goes here

*/

size++;

}

// Add new node n after node p

public void addAfter(DNode<T> p, DNode<T> n) {

DNode<T> pn = p.getNext();

p.setNext(n);

pn.setPrev(n);

n.setNext(pn);

n.setPrev(p);

/*

* Your code goes here

*/

size++;

}

// Remove a node p

public void remove(DNode<T> p) {

p.getPrev().setNext(p.getNext());

p.getNext().setPrev(p.getPrev());

p.setPrev(null);

p.setNext(null);

size--;

}

public DNode<T> getFirstNode() {

if (size == 0) return null;

else

return header.getNext();

}

public DNode<T> getNextNode(DNode<T> cur) {

if(size == 0) return null;

else

return cur.getNext();

/*

* Your code goes here

*/

}

public DNode<T> getLastNode() {

if (size == 0) return null;

else

return trailer.getPrev();

}

public int getSize(){

int k = size;

return k;

}

// Add methods if necessary

}