Linklist-in-cpp

A linked list is a linear data structure that includes a series of connected nodes. Here, each node stores the data and the address of the next node. For example,

u have to start somewhere, so we give the address of the first node a special name called HEAD. Also, the last node in the linked list can be identified because its next portion points to NULL.

Linked lists can be of multiple types: singly, doubly, and circular linked list. In this article, we will focus on the singly linked list. To learn about other types, visit Types of Linked List.
Representation of Linked List
Let's see how each node of the linked list is represented. Each node consists:

A data item
An address of another node
We wrap both the data item and the next node reference in a struct as:

struct node
{
  int data;
  struct node *next;
};
Understanding the structure of a linked list node is the key to having a grasp on it.


Each struct node has a data item and a pointer to another struct node. Let us create a simple Linked List with three items to understand how this works.

/* Initialize nodes */
struct node *head;
struct node *one = NULL;
struct node *two = NULL;
struct node *three = NULL;

/* Allocate memory */
one = malloc(sizeof(struct node));
two = malloc(sizeof(struct node));
three = malloc(sizeof(struct node));

/* Assign data values */
one->data = 1;
two->data = 2;
three->data=3;

/* Connect nodes */
one->next = two;
two->next = three;
three->next = NULL;

/* Save address of first node in head */
head = one;

If you didn't understand any of the lines above, all you need is a refresher on pointers and structs.

In just a few steps, we have created a simple linked list with three nodes.
The power of a linked list comes from the ability to break the chain and rejoin it. E.g. if you wanted to put an element 4 between 1 and 2, the steps would be:

Create a new struct node and allocate memory to it.
Add its data value as 4
Point its next pointer to the struct node containing 2 as the data value
Change the next pointer of "1" to the node we just created.
Doing something similar in an array would have required shifting the positions of all the subsequent elements.

In python and Java, the linked list can be implemented using classes as shown in the codes below.

Linked List Utility
Lists are one of the most popular and efficient data structures, with implementation in every programming language like C, C++, Python, Java, and C#.

Apart from that, linked lists are a great way to learn how pointers work. By practicing how to manipulate linked lists, you can prepare yourself to learn more advanced data structures like graphs and trees.

// Linked list implementation in C++

#include <bits/stdc++.h>
#include <iostream>
using namespace std;

// Creating a node
class Node {
   public:
  int value;
  Node* next;
};

int main() {
  Node* head;
  Node* one = NULL;
  Node* two = NULL;
  Node* three = NULL;

  // allocate 3 nodes in the heap
  one = new Node();
  two = new Node();
  three = new Node();

  // Assign value values
  one->value = 1;
  two->value = 2;
  three->value = 3;

  // Connect nodes
  one->next = two;
  two->next = three;
  three->next = NULL;

  // print the linked list value
  head = one;
  while (head != NULL) {
    cout << head->value;
    head = head->next;
  }
}

Linked List Complexity
Time Complexity

 	Worst case	Average Case
Search	O(n)	O(n)
Insert	O(1)	O(1)
Deletion	O(1)	O(1)
Space Complexity: O(n)


// Function to insert a new node at the end of the list void 
insertAtEnd(Node* &head, int value) { 
  // Create a new node and allocate memory 
  Node* newNode = new Node(); 
  // Assign the value and set the next pointer to NULL 
  newNode->value = value; 
  newNode->next = NULL; 
  // If the list is empty, make the new node as the head 
  if (head == NULL) 
    { 
      head = newNode; 
      return; 
    } 
  // Traverse the list to find the last node 
  Node* temp = head; 
  while (temp->next != NULL) 
    { 
      temp = temp->next; 
    } 
  // Link the last node to the new node 
  temp->next = newNode; 
}

You can use these functions to insert nodes at different positions in your linked list. For example, if you want to insert a node with value 4 at the end of your list, you can call:

=======
A linked list is a linear data structure that includes a series of connected nodes. Here, each node stores the data and the address of the next node. For example,

u have to start somewhere, so we give the address of the first node a special name called HEAD. Also, the last node in the linked list can be identified because its next portion points to NULL.

Linked lists can be of multiple types: singly, doubly, and circular linked list. In this article, we will focus on the singly linked list. To learn about other types, visit Types of Linked List.
Representation of Linked List
Let's see how each node of the linked list is represented. Each node consists:

A data item
An address of another node
We wrap both the data item and the next node reference in a struct as:

struct node
{
  int data;
  struct node *next;
};
Understanding the structure of a linked list node is the key to having a grasp on it.


Each struct node has a data item and a pointer to another struct node. Let us create a simple Linked List with three items to understand how this works.

/* Initialize nodes */
struct node *head;
struct node *one = NULL;
struct node *two = NULL;
struct node *three = NULL;

/* Allocate memory */
one = malloc(sizeof(struct node));
two = malloc(sizeof(struct node));
three = malloc(sizeof(struct node));

/* Assign data values */
one->data = 1;
two->data = 2;
three->data=3;

/* Connect nodes */
one->next = two;
two->next = three;
three->next = NULL;

/* Save address of first node in head */
head = one;

If you didn't understand any of the lines above, all you need is a refresher on pointers and structs.

In just a few steps, we have created a simple linked list with three nodes.
The power of a linked list comes from the ability to break the chain and rejoin it. E.g. if you wanted to put an element 4 between 1 and 2, the steps would be:

Create a new struct node and allocate memory to it.
Add its data value as 4
Point its next pointer to the struct node containing 2 as the data value
Change the next pointer of "1" to the node we just created.
Doing something similar in an array would have required shifting the positions of all the subsequent elements.

In python and Java, the linked list can be implemented using classes as shown in the codes below.

Linked List Utility
Lists are one of the most popular and efficient data structures, with implementation in every programming language like C, C++, Python, Java, and C#.

Apart from that, linked lists are a great way to learn how pointers work. By practicing how to manipulate linked lists, you can prepare yourself to learn more advanced data structures like graphs and trees.

// Linked list implementation in C++

#include <bits/stdc++.h>
#include <iostream>
using namespace std;

// Creating a node
class Node {
   public:
  int value;
  Node* next;
};

int main() {
  Node* head;
  Node* one = NULL;
  Node* two = NULL;
  Node* three = NULL;

  // allocate 3 nodes in the heap
  one = new Node();
  two = new Node();
  three = new Node();

  // Assign value values
  one->value = 1;
  two->value = 2;
  three->value = 3;

  // Connect nodes
  one->next = two;
  two->next = three;
  three->next = NULL;

  // print the linked list value
  head = one;
  while (head != NULL) {
    cout << head->value;
    head = head->next;
  }
}

Linked List Complexity
Time Complexity

 	Worst case	Average Case
Search	O(n)	O(n)
Insert	O(1)	O(1)
Deletion	O(1)	O(1)
Space Complexity: O(n)


// Function to insert a new node at the end of the list void 
insertAtEnd(Node* &head, int value) { 
  // Create a new node and allocate memory 
  Node* newNode = new Node(); 
  // Assign the value and set the next pointer to NULL 
  newNode->value = value; 
  newNode->next = NULL; 
  // If the list is empty, make the new node as the head 
  if (head == NULL) 
    { 
      head = newNode; 
      return; 
    } 
  // Traverse the list to find the last node 
  Node* temp = head; 
  while (temp->next != NULL) 
    { 
      temp = temp->next; 
    } 
  // Link the last node to the new node 
  temp->next = newNode; 
}

You can use these functions to insert nodes at different positions in your linked list. For example, if you want to insert a node with value 4 at the end of your list, you can call:
insertAtEnd(head, 4);