Program To Create A Singly Linked List Of N Nodes And Count The Number Of Nodes

Explanation

In this program, we need to create a singly linked list and count the nodes present in the list.

Program to create a singly linked list of n nodes and count the number of nodes

To accomplish this task, traverse through the list using node current which initially points to head. Increment current in such a way that current will point to its next node in each iteration and increment variable count by 1. In the end, the count will hold the value which denotes the number of nodes present in the list.

Algorithm

Create a class Node which has two attributes: data and next. Next is a pointer to the next node in the list.
Create another class which has two attributes: head and tail.
addNode() will add a new node to the list:
1. Create a new node.
2. It first checks, whether the head is equal to null which means the list is empty.
3. If the list is empty, both head and tail will point to the newly added node.
4. If the list is not empty, the new node will be added to end of the list such that tail’s next will point to a newly added node. This new node will become the new tail of the list.
countNodes() will count the nodes present in the list:
1. Define a node current which will initially point to the head of the list.
2. Declare and initialize a variable count to 0.
3. Traverse through the list till current point to null.
4. Increment the value of count by 1 for each node encountered in the list.
display() will display the nodes present in the list:
1. Define a node current which will initially point to the head of the list.
2. Traverse through the list till current points to null.
3. Display each node by making current to point to node next to it in each iteration.

Solution

Python

  #Represent a node of the singly linked list  class Node:      def __init__(self,data):          self.data = data;          self.next = None;            class CountNodes:      #Represent the head and tail of the singly linked list      def __init__(self):          self.head = None;          self.tail = None;                #addNode() will add a new node to the list      def addNode(self, data):          #Create a new node          newNode = Node(data);                    #Checks if the list is empty          if(self.head == None):              #If list is empty, both head and tail will point to new node              self.head = newNode;              self.tail = newNode;          else:              #newNode will be added after tail such that tail’s next will point to newNode              self.tail.next = newNode;              #newNode will become new tail of the list              self.tail = newNode;                    #countNodes() will count the nodes present in the list      def countNodes(self):          count = 0;          #Node current will point to head          current = self.head;                    while(current != None):              #Increment the count by 1 for each node              count = count + 1;              current = current.next;          return count;            #display() will display all the nodes present in the list      def display(self):          #Node current will point to head          current = self.head;                    if(self.head == None):              print(“List is empty”);              return;          print(“Nodes of singly linked list: “);          while(current != None):              #Prints each node by incrementing pointer              print(current.data),              current = current.next;            sList = CountNodes();            #Add nodes to the list  sList.addNode(1);  sList.addNode(2);  sList.addNode(3);  sList.addNode(4);     #Displays the nodes present in the list  sList.display();     #Counts the nodes present in the given list  print(“Count of nodes present in the list: ” + str(sList.countNodes()));  

Output:

 Nodes of singly linked list:   1 2 3 4   Count of nodes present in the list: 4

C

  #include <stdio.h>     //Represent a node of singly linked list  struct node{      int data;      struct node *next;  };         //Represent the head and tail of the singly linked list  struct node *head, *tail = NULL;     //addNode() will add a new node to the list  void addNode(int data) {      //Create a new node      struct node *newNode = (struct node*)malloc(sizeof(struct node));      newNode->data = data;      newNode->next = NULL;            //Checks if the list is empty      if(head == NULL) {          //If list is empty, both head and tail will point to new node          head = newNode;          tail = newNode;      }      else {          //newNode will be added after tail such that tail’s next will point to newNode          tail->next = newNode;          //newNode will become new tail of the list          tail = newNode;      }  }     //countNodes() will count the nodes present in the list  int countNodes() {      int count = 0;      //Node current will point to head      struct node *current = head;            while(current != NULL) {          //Increment the count by 1 for each node          count++;          current = current->next;      }      return count;  }        //display() will display all the nodes present in the list  void display() {      //Node current will point to head      struct node *current = head;            if(head == NULL) {          printf(“List is emptyn”);          return;      }      printf(“Nodes of singly linked list: n”);      while(current != NULL) {          //Prints each node by incrementing pointer          printf(“%d “, current->data);          current = current->next;      }      printf(“n”);  }        int main()  {      //Add nodes to the list      addNode(1);      addNode(2);      addNode(3);      addNode(4);            //Displays the nodes present in the list      display();            //Counts the nodes present in the given list      printf(“Count of nodes present in the list: %d”, countNodes());         return 0;  }  

Output:

Nodes of singly linked list:   1 2 3 4   Count of nodes present in the list: 4

JAVA

  public class CountNodes {            //Represent a node of singly linked list      class Node{          int data;          Node next;                    public Node(int data) {              this.data = data;              this.next = null;          }      }         //Represent the head and tail of the singly linked list      public Node head = null;      public Node tail = null;            //addNode() will add a new node to the list      public void addNode(int data) {          //Create a new node          Node newNode = new Node(data);                    //Checks if the list is empty          if(head == null) {              //If list is empty, both head and tail will point to new node              head = newNode;              tail = newNode;          }          else {              //newNode will be added after tail such that tail’s next will point to newNode              tail.next = newNode;              //newNode will become new tail of the list              tail = newNode;          }      }            //countNodes() will count the nodes present in the list      public int countNodes() {          int count = 0;          //Node current will point to head          Node current = head;                    while(current != null) {              //Increment the count by 1 for each node              count++;              current = current.next;          }          return count;      }                //display() will display all the nodes present in the list      public void display() {          //Node current will point to head          Node current = head;          if(head == null) {              System.out.println(“List is empty”);              return;          }          System.out.println(“Nodes of singly linked list: “);          while(current != null) {              //Prints each node by incrementing pointer              System.out.print(current.data + ” “);              current = current.next;          }          System.out.println();      }            public static void main(String[] args) {                    CountNodes sList = new CountNodes();                    //Add nodes to the list          sList.addNode(1);          sList.addNode(2);          sList.addNode(3);          sList.addNode(4);                    //Displays the nodes present in the list          sList.display();                    //Counts the nodes present in the given list          System.out.println(“Count of nodes present in the list: ” + sList.countNodes());      }  }  

Output:

Nodes of the singly linked list:  1 2 3 4   Count of nodes present in the list: 4

C#

  using System;                        public class CountNodes  {      //Represent a node of singly linked list      public class Node<T>{          public T data;          public Node<T> next;                    public Node(T value) {              data = value;              next = null;          }      }                public class SinglyLinkedList<T>{          //Represent the head and tail of the singly linked list          public Node<T> head = null;                        public Node<T> tail = null;                //addNode() will add a new node to the list          public void addNode(T data) {              //Create a new node              Node<T> newNode = new Node<T>(data);                 //Checks if the list is empty              if(head == null) {                  //If list is empty, both head and tail will point to new node                  head = newNode;                  tail = newNode;              }              else {                  //newNode will be added after tail such that tail’s next will point to newNode                  tail.next = newNode;                  //newNode will become new tail of the list                  tail = newNode;              }          }                    //countNodes() will count the nodes present in the list          public int countNodes() {              int count = 0;              //Node current will point to head              Node<T> current = head;                 while(current != null) {                  //Increment the count by 1 for each node                  count++;                  current = current.next;              }              return count;          }                    //display() will display all the nodes present in the list          public void display() {              //Node current will point to head              Node<T> current = head;                            if(head == null) {                  Console.WriteLine(“List is empty”);                  return;              }              Console.WriteLine(“Nodes of singly linked list: “);              while(current != null) {                  //Prints each node by incrementing pointer                  Console.Write(current.data + ” “);                  current = current.next;              }              Console.WriteLine();          }      }            public static void Main()      {          SinglyLinkedList<int> sList = new SinglyLinkedList<int>();                    //Add nodes to the list          sList.addNode(1);          sList.addNode(2);          sList.addNode(3);          sList.addNode(4);                    //Displays the nodes present in the list          sList.display();                        //Counts the nodes present in the given list          Console.WriteLine(“Count of nodes present in the list: ” + sList.countNodes());      }  }  

Output:

Nodes of singly linked list:   1 2 3 4   Count of nodes present in the list: 4

PHP

  <!DOCTYPE html>  <html>  <body>  <?php  //Represent a node of singly linked list  class Node{      public $data;      public $next;            function __construct($data){          $this->data = $data;          $this->next = NULL;      }  }  class CountNodes{      //Represent the head and tail of the singly linked list      public $head;      public $tail;      function __construct(){          $this->head = NULL;          $this->tail = NULL;      }            //addNode() will add a new node to the list      function addNode($data) {          //Create a new node          $newNode = new Node($data);                    //Checks if the list is empty          if($this->head == NULL) {              //If list is empty, both head and tail will point to new node              $this->head = $newNode;              $this->tail = $newNode;          }          else {              //newNode will be added after tail such that tail’s next will point to newNode              $this->tail->next = $newNode;              //newNode will become new tail of the list              $this->tail = $newNode;          }      }            //countNodes() will count the nodes present in the list      function countNodes() {          $count = 0;          //Node current will point to head          $current = $this->head;                    while($current != NULL) {              //Increment the count by 1 for each node              $count++;              $current = $current->next;          }          return $count;      }                //display() will display all the nodes present in the list      function display() {          //Node current will point to head          $current = $this->head;                    if($this->head == NULL) {              print(“List is empty <br>”);              return;          }          print(“Nodes of singly linked list: <br>”);          while($current != NULL) {              //Prints each node by incrementing pointer              print($current->data . ” “);              $current = $current->next;          }          print(“<br>”);      }  }        $sList = new CountNodes();            //Add nodes to the list  $sList->addNode(1);  $sList->addNode(2);  $sList->addNode(3);  $sList->addNode(4);     //Displays the nodes present in the list  $sList->display();        //Counts the nodes present in the given list  print(“Count of nodes present in the list: ” . $sList->countNodes());  ?>  </body>  </html>  

Output:

Nodes of singly linked list:   1 2 3 4   Count of nodes present in the list: 4

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Program To Create A Singly Linked List Of N Nodes And Count The Number Of Nodes