implementationLL.java

import java.io.EOFException;
import java.util.List;

class SLL{//user defined data structure
    Node head;
    Node tail;
    int si;
    void insertAtEnd(int val){
        Node temp=new Node(val);
        if(head==null){
            head=tail=temp;
        }
        else{
            tail.next=temp;
            tail=temp;

        }
        si++;
    }
    void display(){
        Node temp=head;
     while(temp!=null){
            System.out.println(temp.val);
            temp=temp.next;
          }
    }
    void size(){
        System.out.println("length of linked list is:"+si);
    }
    void insertAtHead(int val){
        Node temp=new Node(val);
        if(head==null){
            head=tail=temp;
        }
        else{
            temp.next=head;
            head=temp;
        }
    }
    void insert(int idx,int val){
        if(idx==0){
            insertAtHead(val);
            return;
        }
        if(idx==si){
            insertAtEnd(val);
            return;
        }
        if(idx>si){
            System.out.println("Invalid index");
            return;
        }
        Node temp=new Node(val);
        Node x=head;
        for(int i=1;i<=idx-1;i++){
            x=x.next;
            
        }
        temp.next=x.next;
        x.next=temp;
    }
    int get(int idx){
        if(idx<si){
        return tail.val;
        }
        if(idx>=si||idx<0){
            System.out.println("invalid index");
            return -1;
        }
        Node temp=head;
        for(int i=0;i<=idx;i++){
            temp=temp.next;
        }
        return temp.val;

    }
    void deleteAtHead() throws Error{
        if(head==null){
            throw new Error("list is empty");
        }
        head=head.next;
        si--;
    }
    void deleteAtIndex(int idx)throws Error{
        if(idx==0){
            deleteAtHead();
            return;
        }
        if(head==null){
            throw new Error("list is empty");
        }
        if(idx<0||idx>si){
            throw new Error("invalid index");
        }
        Node temp=head;
        for(int i=1;i<idx;i++){
            temp=temp.next;
        }
        if(temp.next==tail){
            tail=temp;
        }
        temp.next=temp.next.next;
        si--;

    }
    

}


public class implementationLL {
    public static void main(String[] args) {
        SLL list=new SLL();
        list.insertAtEnd(10);
         list.insertAtEnd(20);
          list.insertAtEnd(30);
          list.insertAtHead(5);
        
       // list.display();
        //list.size();
       // System.out.println(list.head.val);
       // list.insert(2, 90);
       list.display();
        System.out.println(list.get(1));
       // list.deleteAtHead();
       // list.display();
       list.deleteAtIndex(3);
       list.display();
       System.out.println(list.tail.val);
    }
    
}