Insert node at end of linked list in c++

Write a program which is create and add linked list node at the end (tail, last) position in c++ language.

Suppose we are inserted the following (10, 20, 30 ,40 ,50) node in a sequence.

insert node at end of linked list
// Include header file
#include <iostream>
using namespace std;
// C++ Program for
// Insert linked list element at end position set A

// Linked list node
class LinkNode
{
    public: int data;
    LinkNode *next;
    LinkNode(int data)
    {
        this->data = data;
        this->next = NULL;
    }
};
class SingleLL
{
    public: LinkNode *head;
    SingleLL()
    {
        this->head = NULL;
    }
    // Add new node at the end of linked list
    void addNode(int value)
    {
        //Create  node
        LinkNode *node = new LinkNode(value);
        if (this->head == NULL)
        {
            this->head = node;
        }
        else
        {
            LinkNode *temp = this->head;
            // find last node
            while (temp->next != NULL)
            {
                // Visit to next node
                temp = temp->next;
            }
            // Add node at last position
            temp->next = node;
        }
    }
    //Display all Linked List elements
    void display()
    {
        if (this->head != NULL)
        {
            LinkNode *temp = this->head;
            while (temp != NULL)
            {
                // Display node value
                cout << temp->data << " → ";
                // Visit to next node
                temp = temp->next;
            }
        }
       
            cout << "NULL";
        
    }
};
int main()
{
    SingleLL *sll = new SingleLL();
    // Linked list
    // 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → NULL
    sll->addNode(1);
    sll->addNode(2);
    sll->addNode(3);
    sll->addNode(4);
    sll->addNode(5);
    sll->addNode(6);
    sll->addNode(7);
    sll->addNode(8);
    cout << "Linked List \n";
    sll->display();
    return 0;
}
Linked List
1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → NULL

Time complexity of above program is O(n). We can optimize above algorithm using one extra pointer. Which is hold the reference of last node. Below are implementation of this logic.

// Include header file
#include <iostream>

using namespace std;
// C++ Program for
// Insert linked list element at end position set B

// Linked list node
class LinkNode
{
    public: int data;
    LinkNode *next;
    // constructor of node
    LinkNode(int data)
    {
        this->data = data;
        this->next = NULL;
    }
};
class SingleLL
{
    public: LinkNode *head;
    LinkNode *tail;
    SingleLL()
    {
        // Set inital value
        this->head = NULL;
        this->tail = NULL;
    }
    // Add new node at the end of linked list
    void addNode(int value)
    {
        // Create a new node
        LinkNode *node = new LinkNode(value);
        if (this->head == NULL)
        {
            this->head = node;
        }
        else
        {
            this->tail->next = node;
        }
        this->tail = node;
    }
    // Display linked list element
    void display()
    {
        if (this->head == NULL)
        {
            return;
        }
        LinkNode *temp = this->head;
        // iterating linked list elements
        while (temp != NULL)
        {
            cout << temp->data << " → ";
            // Visit to next node
            temp = temp->next;
        }
        cout << " NULL\n";
    }
};
int main()
{
    SingleLL *sll = new SingleLL();
    // Linked list
    // 10 → 20 → 30 → 40 → 50 → NULL
    sll->addNode(10);
    sll->addNode(20);
    sll->addNode(30);
    sll->addNode(40);
    sll->addNode(50);
    cout << "Linked List \n";
    sll->display();
    return 0;
}
 Linked List
 10 → 20 → 30 → 40 → 50 → NULL

Time complexity of above program is O(1).



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