linked_list_3.cpp

#include <iostream>
using namespace std;

class Node
{
public:
    int data;
    Node* next;

    Node(int data){
        this->data=data;
        next=NULL;
    }

};

//--------------------- Creating linked list by user input-------------------//
Node* takeInput()
{
    int data;
    cin>>data;
    Node* head=NULL;
    //ek head pointer banake value NULL rakh liye
    while(data != -1){
        //jb tk inputted value -1 na ho tb tk ye loop chalega
        //now ek naya node banayenge dynamically
        Node* newNode = new Node(data);

        //agar head ki value null hai means sbse pehle node create ho rha hai
        //so head me new node ke value daal denge
        if(head==NULL){
             head=newNode;
        }
       else{
        //agar head ki value null nhi hui means hm dusra node ya usse aage ka node
        //bna rhe hain to hme nodes ko link bhi krna hai
        Node* temp=head;
        //temp node bana lenge and temp ko traverse krke last wale node tk le jayenge

        while(temp->next!=NULL){
            temp=temp->next;
        }
        //and then temp ke  address me new node daal denge
        temp->next=newNode;
       }
        cin>>data;
    }
    return head;
}
//this function takes O(n^2) time complexity so will improve its efficiency
//jo ek extra while loop chal rha hai to find out last node uske jagah hm
//ek tail pointer rakhlenge jo last node ka address constant time me bata dega

Node* takeInput1()
{
    int data;
    cin>>data;
    Node* head=NULL;
    Node* tail=NULL;
    while(data != -1){
        Node* newNode = new Node(data);
        if(head==NULL){
             head=newNode;
             tail=newNode;
        }
       else{
        tail->next=newNode;
        tail=tail->next;
        //OR
        //tail=newNode;
       }
        cin>>data;
    }
    return head;
}

//---------------------Insert Node at a given position--------------------//
void insertNode(Node* head,int i,int data){
    //ek new node banake usme data rakh liye
    Node* newNode = new Node(data);
    //ek counter bhi rakh lenge index tak pahunchne ke liye
    int counter=0;
    //temp node
    Node* temp=head;
    //now loop chalake jahan node insert krna hai usse ek pehle ka pahunhenge
    //jaise if we have to insert node at index 3 then we will reach at index 2
    //counter<3-1
    while(counter<i-1){
        temp=temp->next;
        counter++;
    }
    //now hamara pointer index se ek pehle wale node pr aa chuka hai
    //now us node se address hatake dusre node me store krenge
    Node* a=temp->next;
    //us jagah pe ab new node ka address dal denge
    temp->next=newNode;
    //newnode ke next me a wala address dal denge
    newNode->next = a;


}

//---------------------Delete Node at a given position--------------------//
void deleteNode(Node* head,int i){
    int counter=0;
    Node* temp=head;
    while(counter<i-1){
        temp=temp->next;
        counter++;
    }
    Node* a = temp->next;
    Node* b = a->next;
    temp->next = b;
    delete a;

}


//--------------------- Printing linked list --------------------//
void print(Node* head)
{
    //direct head node ko use nhi krenge pehle ek temp node bna lenge
        //so that operation ke baad bhi head ka value change nhi ho
        Node* temp = head;
        while(temp!=NULL){

        //pehle data print krenge
        cout<<temp->data<<endl;
        //ab temp ka value aage kr denge means temp me temp ka next value dal denge
        temp=temp->next;
        //aisa tb tk krenge jab tk temp null na ho jaye
    }
}

int main()
{
    //we will make linked list according to user inputted value
    Node* head=takeInput();
    print(head);
    /*int i,data;
    insertNode(head,2,56);
    print(head);*/

    return 0;
}