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Doubly_linked_list.java
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Doubly_linked_list.java
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import java.util.*;
class Node
{
int data;
Node prev;
Node next;
int size=0;
Node(int d,Node p,Node n)
{
data=d;
next=n;
prev=p;
}
public void setData(int d)
{
data=d;
}
public void setLinknext(Node n)
{
next=n;
}
public void setLinkprev(Node p)
{
prev=p;
}
public int getData()
{
return data;
}
public Node getLinknext()
{
return next;
}
public Node getLinkprev()
{
return prev;
}
}
class LinkedList
{
Node start;
Node end;
int size;
LinkedList()
{
start=null;
end=null;
size=0;
}
public void InsertAtFirst(int d)
{
Node nptr=new Node(d,null,null);
if(start==null)
{
start=nptr;
end=nptr;
size++;
}
else
{
nptr.setLinknext(start);
start.setLinkprev(nptr);
start=nptr;
size++;
}
}
public void InsertAtEnd(int d)
{
Node nptr=new Node(d,null,null);
if(start==null)
{
start=nptr;
end=nptr;
size++;
}
else
{
end.setLinknext(nptr);
nptr.setLinkprev(end);
end=nptr;
size++;
}
}
public void InsertAtPos(int d,int pos)
{
Node nptr=new Node(d,null,null);
pos=pos-1;
if(start==null)
{
start=nptr;
end=nptr;
size++;
}
else
{
Node ptr=start;
for(int i=1;i<=size;i++)
{
if (i==pos)
{
Node tmp=ptr.getLinknext();
ptr.setLinknext(nptr);
nptr.setLinkprev(ptr);
nptr.setLinknext(tmp);
tmp.setLinkprev(nptr);
}
ptr=ptr.getLinknext();
}
size++;
}
}
public void DeleteAtEnd()
{
Node ptr=start;
if(start==null)
{
System.out.println("Linked List is Empty");
}
else
{
end=end.getLinkprev();
end.setLinknext(null);
size--;
}
}
public void Display()
{
Node ptr=start;
if(start==null)
{
System.out.println("Linked list is Empty");
}
else
{
while(ptr!=null)
{
System.out.println("Linked list is:");
for(int i=0;i<size;i++)
{
System.out.println(ptr.getData() + " ");
ptr=ptr.getLinknext();
}
}
}
}
}
class DoublyLinkedList
{
public static void main(String args[])
{
Scanner sc=new Scanner(System.in);
LinkedList list=new LinkedList();
while(true)
{
System.out.println("Enter the choice :\n 1.Insert at first \n 2.Delete at end \n 3.Insert at any position\n 4.Insert at end\n 5.Exit");
int ch=sc.nextInt();
switch(ch)
{
case 1: System.out.println("Enter the element to be inserted");
list.InsertAtFirst(sc.nextInt());
list.Display();
break;
case 2: list.DeleteAtEnd();
list.Display();
break;
case 3: System.out.println("Enter the element to be inserted");
int num=sc.nextInt();
System.out.println("Enter the positon");
int p=sc.nextInt();
list.InsertAtPos(num,p);
list.Display();
break;
case 4: System.out.println("Enter the element to be inserted");
list.InsertAtEnd(sc.nextInt());
list.Display();
break;
case 5: System.exit(0);
break;
default:System.out.println("Invalid option");
}
}
}
}