LinkList.java

//PROPERTIES OF LINKLIST
//1. variable sixe
//2. non-contiguous memory
//3. insert in 0(1)
//4. search in 0(n)

//NODE
// NODE store 2 information
//1. data...2. reference

//HEAD means ll ka pehta point amd tail means last elements 

//type pf LL 
//1. SINGULAR....2.DOUBLE ENDED...3.CIRCULAR ...

//BASICALLI INSERTION KE LITE LINKLIST USE KRNA CHAHIYE 

public class LinkList {
 node head;
 private int size; //private size ka int banaya
 
 LinkList(){
 this.size =0; //size ko initialize 0 se kr diya ;;;
 }

 class node { // node cclass bana li hamne
 String data;
 node next;
 

 node(String data) { // CONSTRUCTOR bana liya
 this.data = data;
 this.next = null;
 size++;
 
 }
 

 }

 // ADD--1.FIRST...2.LAST
 //add first
 public void addfirst(String data) {
 node newnode = new node(data); //ek newnode banaya
 if (head == null) {
 head = newnode;
 return;
 }

 newnode.next = head; //head ko new node ke next me dal dila;;;matlab head ek kadam aage gaya 
 head = newnode; //badme new node ko hi head bana diya;;

 }

 // ADD LAST
 public void addlast(String data) {
 node newnode = new node(data);
 if (head == null) {
 head = newnode;
 return;
 }
 node currnode = head; //pehle currnode ko head banaya;;
 while (currnode.next != null) { //jabtak currnode ka head null nahi hota
 currnode = currnode.next; // currnode ka jo next hai usko currnode me dalneka 

 }
 currnode.next = newnode; //currnpde ka next jo hai usko newnode bananeka;;

 }

 // print
 public void printlist() {
 if (head == null) {
 System.out.println(" LL is empty");
 return;
 }
 node currnode = head;
 while (currnode != null) {
 System.out.print(currnode.data + "-->");
 currnode = currnode.next;

 }
 System.out.println("null");
 }

 // DELETE
 // first ko delete karna hai to first ke next ko head banana hoga
 // last ko agr delete karna hai ..to next-next karna hai aur jaise hi second
 // last node tak pohochenge .
 // to second last node ko null bana lenge
 // delete first
 public void deletefirst() {
 if (head == null) {
 System.out.println("LL is empty");
 return;
 

 }
 size--; //delete hone ke bad size ko kam karna padega
 head = head.next; // head.next ko head banaya to head carbej ho gya
 }

 public void deletelast() {
 if (head == null) {
 System.out.println("LL is empty");
 return;
 }
 size --; ////delete hone ke bad size ko kam karna padega 
 node seclast = head; // head ko sechead banaya
 node lastnode = head.next; // head next ko last node banaaya

 if (head.next == null) { // jisme LL me ek hi node hoga //next karte wakt null ka next null nahi ho sakta
 head = null;
 return;
 }

 while (lastnode.next != null) { // jabtak last node null nahi ho jata
 lastnode = lastnode.next; // lastnode next ko last node me dalneka
 seclast = seclast.next; // aur seclast node ke next ko sec last me dalneka jo ki head banaya hai

 }
 seclast.next = null;
 // lastnode = null;

 }
 public int getsize(){
 return size;
 }

 



 public static void main(String[] args) {
 LinkList list = new LinkList();

 list.addfirst("is");
 list.addfirst("varad");
 list.addfirst("a");
 list.printlist();

 list.addlast("good");
 list.printlist();
 list.addlast("but");
 list.addlast("not");
 list.addlast("not");
 
 list.deletelast();
 list.deletefirst();
 list.deletelast();
 list.deletelast();
 list.printlist();
 list.addfirst("a");
 
 list.addlast("so");
 list.printlist();
 System.out.println(list.size);
 
 }

}