![if(tmpRear == null) front = null;
System.out.println("removed from rear: "+rear.getValue());
rear = tmpRear;
}
public static void main(String a[]){
DequeDblLinkedListImpl deque = new DequeDblLinkedListImpl();
deque.insertFront(34);
deque.insertFront(67);
System.out.println("Size of the queue : "+deque.size());
deque.insertFront(29);
deque.insertFront(765);
deque.removeFront();
deque.removeFront();
deque.removeFront();
deque.insertRear(43);
deque.insertRear(83);
deque.insertRear(84);
deque.insertRear(546);
deque.insertRear(356);
deque.removeRear();
deque.removeRear();
deque.removeRear();
deque.removeRear();
deque.removeFront();
deque.removeFront();
deque.removeFront();
}
}
class LinkedNode{
private LinkedNode prev;
private LinkedNode next;
private T value;
public LinkedNode getPrev() {
return prev;
}
public void setPrev(LinkedNode prev) {](https://image.slidesharecdn.com/javaadouble-endedqueueisalistthatallowstheadditionand-230703024011-5526fcb1/85/JAVA-A-double-ended-queue-is-a-list-that-allows-the-addition-and-pdf-3-320.jpg)
JAVA A double-ended queue is a list that allows the addition and.pdf
- 1. **JAVA** A double-ended queue is a list that allows the addition and removal of items from either end. One end is arbitrarily called the front and other the rear, but the two ends behave identically. Specify, design and implement a class for a double-ended queue. Include operations to check if it is empty and to return the number of items in the list. For each end, include operations for adding and deleting items. Use doubly linked list for your implementation. Call your class Deque (pronounced "deck"). Solution //package com.java2novice.ds.queue; public class DequeDblLinkedListImpl { private LinkedNode front; private LinkedNode rear; public void insertFront(T item){ //add element at the beginning of the queue System.out.println("adding at front: "+item); LinkedNode nd = new LinkedNode(); nd.setValue(item); nd.setNext(front); if(front != null) front.setPrev(nd); if(front == null) rear = nd; front = nd; } public void insertRear(T item){ //add element at the end of the queue System.out.println("adding at rear: "+item); LinkedNode nd = new LinkedNode(); nd.setValue(item); nd.setPrev(rear); if(rear != null) rear.setNext(nd); if(rear == null) front = nd; rear = nd; } public void removeFront(){ if(front == null){
- 2. System.out.println("Deque underflow!! unable to remove."); return; } //remove an item from the beginning of the queue LinkedNode tmpFront = front.getNext(); if(tmpFront != null) tmpFront.setPrev(null); if(tmpFront == null) rear = null; System.out.println("removed from front: "+front.getValue()); front = tmpFront; } public int size(){ if(front == null && rear ==null){ return 0; } //remove an item from the beginning of the queue LinkedNode tmpFront = front; LinkedNode tmpRear = rear; int i=0; while(tmpFront != rear) { i++; tmpFront=tmpFront.getNext(); } i++; return i; } public void removeRear(){ if(rear == null){ System.out.println("Deque underflow!! unable to remove."); return; } //remove an item from the beginning of the queue LinkedNode tmpRear = rear.getPrev(); if(tmpRear != null) tmpRear.setNext(null);
- 3. if(tmpRear == null) front = null; System.out.println("removed from rear: "+rear.getValue()); rear = tmpRear; } public static void main(String a[]){ DequeDblLinkedListImpl deque = new DequeDblLinkedListImpl(); deque.insertFront(34); deque.insertFront(67); System.out.println("Size of the queue : "+deque.size()); deque.insertFront(29); deque.insertFront(765); deque.removeFront(); deque.removeFront(); deque.removeFront(); deque.insertRear(43); deque.insertRear(83); deque.insertRear(84); deque.insertRear(546); deque.insertRear(356); deque.removeRear(); deque.removeRear(); deque.removeRear(); deque.removeRear(); deque.removeFront(); deque.removeFront(); deque.removeFront(); } } class LinkedNode{ private LinkedNode prev; private LinkedNode next; private T value; public LinkedNode getPrev() { return prev; } public void setPrev(LinkedNode prev) {
- 4. this.prev = prev; } public LinkedNode getNext() { return next; } public void setNext(LinkedNode next) { this.next = next; } public T getValue() { return value; } public void setValue(T value) { this.value = value; } }