import java.util.*;
class Node {
int data;
Node prev;
Node next;
public Node(int data) {
this.data = data;
this.prev = null;
this.next = null;
}
}
class DoublyLinkedListCalaycay {
Node head;
Node tail;
// Constructor to initialize an empty list.
public DoublyLinkedListCalaycay() {
head = null;
tail = null;
}
// Add a new node to the head of the list.
public void addToHead(int data) {
Node newNode = new Node(data);
if (head == null) {
head = newNode;
tail = newNode;
} else {
newNode.next = head;
head.prev = newNode;
head = newNode;
}
System.out.println("Added " + data + " to the head.");
}
// Add a new node to the tail of the list.
public void addToTail(int data) {
Node newNode = new Node(data);
if (tail == null) {
head = newNode;
tail = newNode;
} else {
tail.next = newNode;
newNode.prev = tail;
tail = newNode;
}
System.out.println("Added " + data + " to the tail.");
}
// Print the data in the head node.
public void printHead() {
if (head != null) {
System.out.println("Head: " + head.data);
} else {
System.out.println("List is empty.");
}
}
// Print the data in the tail node.
public void printTail() {
if (tail != null) {
System.out.println("Tail: " + tail.data);
} else {
System.out.println("List is empty.");
}
}
// Print the data in the list from head to tail.
public void printForward() {
Node current = head;
System.out.print("Forward: ");
while (current != null) {
System.out.print(current.data + " ");
current = current.next;
}
System.out.println();
}
// Print the data in the list from tail to head.
public void printBackward() {
Node current = tail;
System.out.print("Backward: ");
while (current != null) {
System.out.print(current.data + " ");
current = current.prev;
}
System.out.println();
}
// Remove the node from the head of the list.
public void removeFromHead() {
if (head != null) {
if (head == tail) {
head = null;
tail = null;
} else {
head = head.next;
head.prev = null;
}
System.out.println("Removed from head.");
} else {
System.out.println("List is empty.");
}
}
// Remove the node from the tail of the list.
public void removeFromTail() {
if (tail != null) {
if (head == tail) {
head = null;
tail = null;
} else {
tail = tail.prev;
tail.next = null;
}
System.out.println("Removed from tail.");
} else {
System.out.println("List is empty.");
}
}
// Insert a new node after a specific item.
public void insertNodeAfter(int searchItem, int itemToInsert) {
Node newNode = new Node(itemToInsert);
Node current = head;
while (current != null) {
if (current.data == searchItem) {
newNode.prev = current;
newNode.next = current.next;
if (current.next != null) {
current.next.prev = newNode;
} else {
tail = newNode;
}
current.next = newNode;
System.out.println("Inserted " + itemToInsert + " after " + searchItem + ".");
return;
}
current = current.next;
}
System.out.println(searchItem + " not found in the list.");
}
// Remove a specific node from the list.
public void removeNode(int itemToRemove) {
Node current = head;
while (current != null) {
if (current.data == itemToRemove) {
if (current == head) {
removeFromHead();
} else if (current == tail) {
removeFromTail();
} else {
current.prev.next = current.next;
current.next.prev = current.prev;
System.out.println("Removed " + itemToRemove + " from the list.");
}
return;
}
current = current.next;
}
System.out.println(itemToRemove + " not found in the list.");
}
}
import java.util.*;
public class DoublyLinkedListDemo {
public static void main(String[] args) {
DoublyLinkedListCalaycay list = new DoublyLinkedListCalaycay();
Scanner scanner = new Scanner(System.in);
while (true) {
System.out.println("Doubly Linked List Operations:");
System.out.println("1 - Add to Head");
System.out.println("2 - Add to Tail");
System.out.println("3 - Print Head");
System.out.println("4 - Print Tail");
System.out.println("5 - Print Forward");
System.out.println("6 - Print Backward");
System.out.println("7 - Remove from Head");
System.out.println("8 - Remove from Tail");
System.out.println("9 - Insert Node After");
System.out.println("10 - Remove Node");
System.out.println("11 - Quit");
System.out.print("Enter your choice (1-11): ");
int choice = scanner.nextInt();
switch (choice) {
case 1:
System.out.print("Enter value to add to the head: ");
int data = scanner.nextInt();
list.addToHead(data);
break;
case 2:
System.out.print("Enter value to add to the tail: ");
data = scanner.nextInt();
list.addToTail(data);
break;
case 3:
list.printHead();
break;
case 4:
list.printTail();
break;
case 5:
list.printForward();
break;
case 6:
list.printBackward();
break;
case 7:
list.removeFromHead();
break;
case 8:
list.removeFromTail();
break;
case 9:
System.out.print("Enter the item to search for: ");
int searchItem = scanner.nextInt();
System.out.print("Enter the item to insert after: ");
int itemToInsert = scanner.nextInt();
list.insertNodeAfter(searchItem, itemToInsert);
break;
case 10:
System.out.print("Enter the item to remove: ");
int itemToRemove = scanner.nextInt();
list.removeNode(itemToRemove);
break;
case 11:
System.out.println("Exiting...");
scanner.close();
System.exit(0);
default:
System.out.println("Invalid choice. Please enter a valid option.");
}
}
}
}
