Program To Sort The Elements Of The Singly Linked List

Explanation

In this program, we need to sort the nodes of the given singly linked list in ascending order.

Original list:

Sorted list:

To accomplish this task, we maintain two pointers: current and index. Initially, current point to head node and index will point to node next to current. Traverse through the list till current points to null, by comparing current’s data with index’s data. If current’s data is greater than the index’s data, then swap data between them. In the above example, current will initially point to 9 and index will point to 7. Since, 9 is greater than 7, swap the data. Continue this process until the entire list is sorted in ascending order.

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 SortList 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 a 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.
sortList() will sort the nodes of the list in ascending order.
1. Define a node current which will point to head.
2. Define another node index which will point to node next to current.
3. Compare data of current and index node. If current’s data is greater than the index’s data then, swap the data between them.
4. Current will point to current.next and index will point to index.next.
5. Continue this process until the entire list is sorted.
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 SortList:      #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;                    #sortList() will sort nodes of the list in ascending order      def sortList(self):          #Node current will point to head          current = self.head;          index = None;                    if(self.head == None):              return;          else:              while(current != None):                  #Node index will point to node next to current                  index = current.next;                                    while(index != None):                      #If current node’s data is greater than index’s node data, swap the data between them                      if(current.data > index.data):                          temp = current.data;                          current.data = index.data;                          index.data = temp;                      index = index.next;                  current = current.next;                        #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;          while(current != None):              #Prints each node by incrementing pointer              print(current.data),              current = current.next;          print “”     sList = SortList();            #Adds data to the list  sList.addNode(9);  sList.addNode(7);  sList.addNode(2);  sList.addNode(5);  sList.addNode(4);     #Displaying original list  print(“Original list: “);  sList.display();    #Sorting list  sList.sortList();     #Displaying sorted list  print(“Sorted list: “);  sList.display();  

Output:

 Original list:   9 7 2 5 4   Sorted list:   2 4 5 7 9

C

  #include <stdio.h>     //Represent a node of the 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;      }  }         //sortList() will sort nodes of the list in ascending order      void sortList() {          //Node current will point to head          struct node *current = head, *index = NULL;          int temp;                    if(head == NULL) {              return;          }          else {              while(current != NULL) {                  //Node index will point to node next to current                  index = current->next;                                    while(index != NULL) {                      //If current node’s data is greater than index’s node data, swap the data between them                      if(current->data > index->data) {                          temp = current->data;                          current->data = index->data;                          index->data = temp;                      }                      index = index->next;                  }                  current = current->next;              }              }      }     //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 empty n”);          return;      }      while(current != NULL) {          //Prints each node by incrementing pointer          printf(“%d “, current->data);          current = current->next;      }      printf(“n”);  }        int main()  {      //Adds data to the list      addNode(9);      addNode(7);      addNode(2);      addNode(5);      addNode(4);            //Displaying original list      printf(“Original list: n”);      display();            //Sorting list      sortList();            //Displaying sorted list      printf(“Sorted list: n”);      display();                return 0;  }  

Output:

Original list:   9 7 2 5 4   Sorted list:   2 4 5 7 9

JAVA

  public class SortList {            //Represent a node of the 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;          }      }            //sortList() will sort nodes of the list in ascending order      public void sortList() {          //Node current will point to head          Node current = head, index = null;          int temp;                    if(head == null) {              return;          }          else {              while(current != null) {                  //Node index will point to node next to current                  index = current.next;                                    while(index != null) {                      //If current node’s data is greater than index’s node data, swap the data between them                      if(current.data > index.data) {                          temp = current.data;                          current.data = index.data;                          index.data = temp;                      }                      index = index.next;                  }                  current = current.next;              }              }      }            //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;          }          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) {                    SortList sList = new SortList();                    //Adds data to the list          sList.addNode(9);          sList.addNode(7);          sList.addNode(2);          sList.addNode(5);          sList.addNode(4);                    //Displaying original list          System.out.println(“Original list: “);          sList.display();                    //Sorting list          sList.sortList();                    //Displaying sorted list          System.out.println(“Sorted list: “);          sList.display();      }  }  

Output:

Original list:   9 7 2 5 4   Sorted list:   2 4 5 7 9

C#

  using System;                        public class CreateList  {      //Represent a node of the singly linked list      public class Node<T>{          public T data;          public Node<T> next;                    public Node(T value) {              data = value;              next = null;          }      }                public class SortList<T> where T : IComparable<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;              }          }                //sortList() will sort nodes of the list in ascending order          public void sortList() {              //Node current will point to head              Node<T> current = head, index = null;              T temp;                 if(head == null) {                  return;              }              else {                  while(current != null) {                      //Node index will point to node next to current                      index = current.next;                         while(index != null) {                          //If current node’s data is greater than index’s node data, swap the data between them                          if(current.data.CompareTo(index.data) > 0) {                              temp = current.data;                              current.data = index.data;                              index.data = temp;                          }                          index = index.next;                      }                      current = current.next;                  }                  }          }                    //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;              }              while(current != null) {                  //Prints each node by incrementing pointer                  Console.Write(current.data + ” “);                  current = current.next;              }              Console.WriteLine();          }      }            public static void Main()      {          SortList<int> sList = new SortList<int>();                    //Adds data to the list          sList.addNode(9);          sList.addNode(7);          sList.addNode(2);          sList.addNode(5);          sList.addNode(4);                    //Displaying original list          Console.WriteLine(“Original list: “);          sList.display();                    //Sorting list          sList.sortList();                    //Displaying sorted list          Console.WriteLine(“Sorted list: “);          sList.display();      }  }  

Output:

Original list:   9 7 2 5 4   Sorted list:   2 4 5 7 9

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 SortList{      //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;          }      }            //sortList() will sort nodes of the list in ascending order      function sortList() {          //Node current will point to head          $current = $this->head;           $index = null;                    if($this->head == null) {              return;          }          else {              while($current != null) {                  //Node index will point to node next to current                  $index = $current->next;                                    while($index != null) {                      //If current node’s data is greater than index’s node data, swap the data between them                      if($current->data > $index->data) {                          $temp = $current->data;                          $current->data = $index->data;                          $index->data = $temp;                      }                      $index = $index->next;                  }                  $current = $current->next;              }              }      }            //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;          }          while($current != NULL) {              //Prints each node by incrementing pointer              print($current->data . ” “);              $current = $current->next;          }          print(“<br>”);      }  }        $sList = new SortList();            //Adds data to the list  $sList->addNode(9);  $sList->addNode(7);  $sList->addNode(2);  $sList->addNode(5);  $sList->addNode(4);     //Displaying original list  print(“Original list: <br>”);  $sList->display();     //Sorting list  $sList->sortList();     //Displaying sorted list  print(“Sorted list: <br>”);  $sList->display();  ?>  </body>  </html>  

Output:

 Original list:   9 7 2 5 4   Sorted list:   2 4 5 7 9

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Program To Sort The Elements Of The Singly Linked List