Data Structures - Circular Singly Linked List Other Related Topics
Data Structures - Circular Singly Linked List Other Related Topics

Circular Singly Linked List - Swap node values

There are many instances where it is required to swap value of two nodes while working with a list. This can be achieved by traversing to the interested nodes and swap their values if the nodes are valid. For example - if the given list is 10->20->30->40->50. After swapping values of first and fourth nodes, the list will become 40->20->30->10->50.

The function swapNodeValues is created for this purpose which is a 4-step process.

void swapNodeValues(int node1, int node2) {
  
  //1. count the number of nodes in the list
  Node* temp = head;
  int N = 0;
  if(temp != NULL) {
    N++;
    temp = temp->next;
  }
  while(temp != head) {
    N++;
    temp = temp->next;
  }

  //2. check if the swap positions are valid entries
  if(node1 < 1 || node1 > N || node2 < 1 || node2 > N)
    return;

  //3. traverse to the nodes where values to be swapped
  Node* pos1 = head;
  Node* pos2 = head;
  for(int i = 1; i < node1; i++) {
    pos1 = pos1->next;
  }
  for(int i = 1; i < node2; i++) {
    pos2 = pos2->next;
  }

  //4. swap the values of two nodes
  int val = pos1->data;
  pos1->data = pos2->data;
  pos2->data = val;
} 

void swapNodeValues(struct Node* head_ref, int node1, int node2) {
  
  //1. count the number of nodes in the list
  struct Node* temp = head_ref;
  int N = 0;
  if(temp != NULL) {
    N++;
    temp = temp->next;
  }
  while (temp != head_ref) {
    N++;
    temp = temp->next;    
  }

  //2. check if the swap positions are valid entries
  if(node1 < 1 || node1 > N || node2 < 1 || node2 > N)
    return;

  //3. traverse to the nodes where values to be swapped
  struct Node* pos1 = head_ref;
  struct Node* pos2 = head_ref;
  for(int i = 1; i < node1; i++) {
    pos1 = pos1->next;
  }
  for(int i = 1; i < node2; i++) {
    pos2 = pos2->next;
  }

  //4. swap the values of two nodes
  int val = pos1->data;
  pos1->data = pos2->data;
  pos2->data = val;   
}

def swapNodeValues(self, node1, node2):
  
  #1. count the number of nodes in the list
  temp = self.head
  N = 0
  if (temp != None):
    N += 1
    temp = temp.next
  while (temp != self.head):
    N += 1
    temp = temp.next

  #2. check if the swap positions are valid entries
  if(node1 < 1 or node1 > N or node2 < 1 or node2 > N):
    return

  #3. traverse to the nodes where values to be swapped
  pos1 = self.head
  pos2 = self.head
  for i in range(1, node1):
    pos1 = pos1.next;
  for i in range(1, node2):
    pos2 = pos2.next;

  #4. swap the values of two nodes
  val = pos1.data
  pos1.data = pos2.data
  pos2.data = val 

void swapNodeValues(int node1, int node2) {
  
  //1. count the number of nodes in the list
  Node temp = new Node();
  temp = this.head;
  int N = 0;
  if (temp != null) {
    N++;
    temp = temp.next;
  }
  while(temp != this.head) {
    N++;
    temp = temp.next;
  } 

  //2. check if the swap positions are valid entries
  if(node1 < 1 || node1 > N || node2 < 1 || node2 > N)
    return;

  //3. traverse to the nodes where values to be swapped
  Node pos1 = this.head;
  Node pos2 = this.head;
  for(int i = 1; i < node1; i++) {
    pos1 = pos1.next;
  }
  for(int i = 1; i < node2; i++) {
    pos2 = pos2.next;
  }

  //4. swap the values of two nodes
  int val = pos1.data;
  pos1.data = pos2.data;
  pos2.data = val;
}   

public void swapNodeValues(int node1, int node2) {
  
  //1. count the number of nodes in the list
  Node temp = new Node();
  temp = this.head;
  int N = 0;
  if (temp != null) {
    N++;
    temp = temp.next;
  }
  while(temp != this.head) {
    N++;
    temp = temp.next;
  } 

  //2. check if the swap positions are valid entries
  if(node1 < 1 || node1 > N || node2 < 1 || node2 > N)
    return;

  //3. traverse to the nodes where values to be swapped
  Node pos1 = this.head;
  Node pos2 = this.head;
  for(int i = 1; i < node1; i++) {
    pos1 = pos1.next;
  }
  for(int i = 1; i < node2; i++) {
    pos2 = pos2.next;
  }

  //4. swap the values of two nodes
  int val = pos1.data;
  pos1.data = pos2.data;
  pos2.data = val; 
}   

public function swapNodeValues($node1, $node2) {
  
  //1. count the number of nodes in the list
  $temp = new Node();
  $temp = $this->head;
  $N = 0;
  if ($temp != null) {
    $N++;
    $temp = $temp->next;
  }
  while($temp != $this->head) {
    $N++;
    $temp = $temp->next;
  } 

  //2. check if the swap positions are valid entries
  if($node1 < 1 || $node1 > $N || $node2 < 1 || $node2 > $N)
    return;

  //3. traverse to the nodes where values to be swapped
  $pos1 = $this->head;
  $pos2 = $this->head;
  for($i = 1; $i < $node1; $i++) {
    $pos1 = $pos1->next;
  }
  for($i = 1; $i < $node2; $i++) {
    $pos2 = $pos2->next;
  }

  //4. swap the values of two nodes
  $val = $pos1->data;
  $pos1->data = $pos2->data;
  $pos2->data = $val;
}

The below is a complete program that uses above discussed concept to swap values of two given nodes of a circular singly linked list.

#include <iostream>
using namespace std;

//node structure
struct Node {
    int data;
    Node* next;
};

class LinkedList {
  private:
    Node* head;
  public:
    LinkedList(){
      head = NULL;
    }
 
    //Add new element at the end of the list
    void push_back(int newElement) {
      Node* newNode = new Node();
      newNode->data = newElement;
      newNode->next = NULL; 
      if(head == NULL) {
        head = newNode;
        newNode->next = head;
      } else {
        Node* temp = head;
        while(temp->next != head)
          temp = temp->next;
        temp->next = newNode;
        newNode->next = head;
      }    
    }

    //swap node values
    void swapNodeValues(int node1, int node2) {
      
      Node* temp = head;
      int N = 0;
      if(temp != NULL) {
        N++;
        temp = temp->next;
      }
      while(temp != head) {
        N++;
        temp = temp->next;
      }

      if(node1 < 1 || node1 > N || node2 < 1 || node2 > N)
        return;

      Node* pos1 = head;
      Node* pos2 = head;
      for(int i = 1; i < node1; i++) {
        pos1 = pos1->next;
      }
      for(int i = 1; i < node2; i++) {
        pos2 = pos2->next;
      }

      int val = pos1->data;
      pos1->data = pos2->data;
      pos2->data = val;
    }  

    //display the content of the list
    void PrintList() {
      Node* temp = head;
      if(temp != NULL) {
        cout<<"The list contains: ";
        while(true) {
          cout<<temp->data<<" ";
          temp = temp->next;
          if(temp == head) 
            break;
        }
        cout<<endl;
      } else {
        cout<<"The list is empty.\n";
      }
    }     
};

// test the code 
int main() {
  LinkedList MyList;

  //Add five elements in the list.
  MyList.push_back(10);
  MyList.push_back(20);
  MyList.push_back(30);
  MyList.push_back(40);
  MyList.push_back(50);

  //Display the content of the list.
  MyList.PrintList();

  //swap values of node=1 and node=4
  MyList.swapNodeValues(1, 4);

  //Display the content of the list.
  MyList.PrintList();
  
  return 0; 
}

The above code will give the following output: 

The list contains: 10 20 30 40 50 
The list contains: 40 20 30 10 50 

#include <stdio.h>
#include <stdlib.h>

//node structure
struct Node {
  int data;
  struct Node* next;
};

//Add new element at the end of the list
void push_back(struct Node** head_ref, int newElement) {  
  struct Node *newNode, *temp;
  newNode = (struct Node*)malloc(sizeof(struct Node)); 
  newNode->data = newElement;  
  newNode->next = NULL;
  if(*head_ref == NULL) {
    *head_ref = newNode;
     newNode->next = *head_ref;
  } else {
    temp = *head_ref;
    while(temp->next != *head_ref) {
      temp = temp->next;
    }    
    temp->next = newNode;
    newNode->next = *head_ref;
  }
}

//swap node values
void swapNodeValues(struct Node* head_ref, int node1, int node2) {
  
  struct Node* temp = head_ref;
  int N = 0;
  if(temp != NULL) {
    N++;
    temp = temp->next;
  }
  while (temp != head_ref) {
    N++;
    temp = temp->next;    
  }

  if(node1 < 1 || node1 > N || node2 < 1 || node2 > N)
    return;

  struct Node* pos1 = head_ref;
  struct Node* pos2 = head_ref;
  for(int i = 1; i < node1; i++) {
    pos1 = pos1->next;
  }
  for(int i = 1; i < node2; i++) {
    pos2 = pos2->next;
  }

  int val = pos1->data;
  pos1->data = pos2->data;
  pos2->data = val;   
}

//display the content of the list
void PrintList(struct Node* head_ref) {
  struct Node* temp = head_ref;
  if(head_ref != NULL) {
    printf("The list contains: ");
    while (1) {
      printf("%i ",temp->data);
      temp = temp->next;
      if(temp == head_ref)
        break;    
    }
    printf("\n");
  } else {
    printf("The list is empty.\n");
  }   
}

// test the code 
int main() {
  struct Node* MyList = NULL;

  //Add five elements in the list.
  push_back(&MyList, 10);
  push_back(&MyList, 20);
  push_back(&MyList, 30);
  push_back(&MyList, 40);
  push_back(&MyList, 50);

  //Display the content of the list.
  PrintList(MyList);

  //swap values of node=1 and node=4
  swapNodeValues(MyList, 1, 4);

  //Display the content of the list.
  PrintList(MyList);

  return 0; 
}

The above code will give the following output: 

The list contains: 10 20 30 40 50 
The list contains: 40 20 30 10 50 

# node structure
class Node:
  def __init__(self, data):
    self.data = data
    self.next = None

#class Linked List
class LinkedList:
  def __init__(self):
    self.head = None

  #Add new element at the end of the list
  def push_back(self, newElement):
    newNode = Node(newElement)
    if(self.head == None):
      self.head = newNode
      newNode.next = self.head
      return
    else:
      temp = self.head
      while(temp.next != self.head):
        temp = temp.next
      temp.next = newNode
      newNode.next = self.head

  #swap node values
  def swapNodeValues(self, node1, node2):
    
    temp = self.head
    N = 0
    if (temp != None):
      N += 1
      temp = temp.next
    while (temp != self.head):
      N += 1
      temp = temp.next

    if(node1 < 1 or node1 > N or node2 < 1 or node2 > N):
      return

    pos1 = self.head
    pos2 = self.head
    for i in range(1, node1):
      pos1 = pos1.next;
    for i in range(1, node2):
      pos2 = pos2.next;

    val = pos1.data
    pos1.data = pos2.data
    pos2.data = val  

  #display the content of the list
  def PrintList(self):
    temp = self.head
    if(temp != None):
      print("The list contains:", end=" ")
      while (True):
        print(temp.data, end=" ")
        temp = temp.next
        if(temp == self.head):
          break
      print()
    else:
      print("The list is empty.")

# test the code                  
MyList = LinkedList()

#Add five elements in the list.
MyList.push_back(10)
MyList.push_back(20)
MyList.push_back(30)
MyList.push_back(40)
MyList.push_back(50)

#Display the content of the list.
MyList.PrintList()

#swap values of node=1 and node=4
MyList.swapNodeValues(1, 4)

#Display the content of the list.
MyList.PrintList()

The above code will give the following output: 

The list contains: 10 20 30 40 50 
The list contains: 40 20 30 10 50 

//node structure
class Node {
    int data;
    Node next;
};

class LinkedList {
  Node head;

  LinkedList(){
    head = null;
  }

  //Add new element at the end of the list
  void push_back(int newElement) {
    Node newNode = new Node();
    newNode.data = newElement;
    newNode.next = null; 
    if(head == null) {
      head = newNode;
      newNode.next = head;
    } else {
      Node temp = new Node();
      temp = head;
      while(temp.next != head)
        temp = temp.next;
      temp.next = newNode;
      newNode.next = head;
    }    
  }

  //swap node values
  void swapNodeValues(int node1, int node2) {
    
    Node temp = new Node();
    temp = this.head;
    int N = 0;
    if (temp != null) {
      N++;
      temp = temp.next;
    }
    while(temp != this.head) {
      N++;
      temp = temp.next;
    } 

    if(node1 < 1 || node1 > N || node2 < 1 || node2 > N)
      return;

    Node pos1 = this.head;
    Node pos2 = this.head;
    for(int i = 1; i < node1; i++) {
      pos1 = pos1.next;
    }
    for(int i = 1; i < node2; i++) {
      pos2 = pos2.next;
    }

    int val = pos1.data;
    pos1.data = pos2.data;
    pos2.data = val;
  }   

  //display the content of the list
  void PrintList() {
    Node temp = new Node();
    temp = this.head;
    if(temp != null) {
      System.out.print("The list contains: ");
      while(true) {
        System.out.print(temp.data + " ");
        temp = temp.next;
        if(temp == this.head)
          break;
      }
      System.out.println();
    } else {
      System.out.println("The list is empty.");
    }
  }     
};

// test the code 
public class Implementation {
  public static void main(String[] args) {
    LinkedList MyList = new LinkedList();

    //Add five elements in the list.
    MyList.push_back(10);
    MyList.push_back(20);
    MyList.push_back(30);
    MyList.push_back(40);
    MyList.push_back(50);

    //Display the content of the list.
    MyList.PrintList();

    //swap values of node=1 and node=4
    MyList.swapNodeValues(1, 4);

    //Display the content of the list.
    MyList.PrintList(); 
  }
}

The above code will give the following output: 

The list contains: 10 20 30 40 50 
The list contains: 40 20 30 10 50 

using System;

//node structure
class Node {
  public int data;
  public Node next;
};

class LinkedList {
  Node head;

  public LinkedList(){
    head = null;
  }
  
  //Add new element at the end of the list
  public void push_back(int newElement) {
    Node newNode = new Node();
    newNode.data = newElement;
    newNode.next = null; 
    if(head == null) {
      head = newNode;
      newNode.next = head;
    } else {
      Node temp = new Node();
      temp = head;
      while(temp.next != head)
        temp = temp.next;
      temp.next = newNode;
      newNode.next = head;
    }    
  }

  //swap node values
  public void swapNodeValues(int node1, int node2) {
    
    Node temp = new Node();
    temp = this.head;
    int N = 0;
    if (temp != null) {
      N++;
      temp = temp.next;
    }
    while(temp != this.head) {
      N++;
      temp = temp.next;
    } 

    if(node1 < 1 || node1 > N || node2 < 1 || node2 > N)
      return;

    Node pos1 = this.head;
    Node pos2 = this.head;
    for(int i = 1; i < node1; i++) {
      pos1 = pos1.next;
    }
    for(int i = 1; i < node2; i++) {
      pos2 = pos2.next;
    }

    int val = pos1.data;
    pos1.data = pos2.data;
    pos2.data = val; 
  }   

  //display the content of the list
  public void PrintList() {
    Node temp = new Node();
    temp = this.head;
    if(temp != null) {
      Console.Write("The list contains: ");
      while(true) {
        Console.Write(temp.data + " ");
        temp = temp.next;
        if(temp == this.head)
          break;        
      }
      Console.WriteLine();
    } else {
      Console.WriteLine("The list is empty.");
    }
  }      
};

// test the code
class Implementation {  
  static void Main(string[] args) {
    LinkedList MyList = new LinkedList();

    //Add five elements in the list.
    MyList.push_back(10);
    MyList.push_back(20);
    MyList.push_back(30);
    MyList.push_back(40);
    MyList.push_back(50);

    //Display the content of the list.
    MyList.PrintList();  

    //swap values of node=1 and node=4
    MyList.swapNodeValues(1, 4);

    //Display the content of the list.
    MyList.PrintList();  
  }
}

The above code will give the following output: 

The list contains: 10 20 30 40 50 
The list contains: 40 20 30 10 50 

<?php
//node structure
class Node {
  public $data;
  public $next;
}

class LinkedList {
  public $head;

  public function __construct(){
    $this->head = null;
  }
  
  //Add new element at the end of the list
  public function push_back($newElement) {
    $newNode = new Node();
    $newNode->data = $newElement;
    $newNode->next = null; 
    if($this->head == null) {
      $this->head = $newNode;
      $newNode->next = $this->head;
    } else {
      $temp = new Node();
      $temp = $this->head;
      while($temp->next !== $this->head) {
        $temp = $temp->next;
      }
      $temp->next = $newNode;
      $newNode->next = $this->head;
    }    
  }

  //swap node values
  public function swapNodeValues($node1, $node2) {
    
    $temp = new Node();
    $temp = $this->head;
    $N = 0;
    if ($temp != null) {
      $N++;
      $temp = $temp->next;
    }
    while($temp != $this->head) {
      $N++;
      $temp = $temp->next;
    } 

    if($node1 < 1 || $node1 > $N || $node2 < 1 || $node2 > $N)
      return;

    $pos1 = $this->head;
    $pos2 = $this->head;
    for($i = 1; $i < $node1; $i++) {
      $pos1 = $pos1->next;
    }
    for($i = 1; $i < $node2; $i++) {
      $pos2 = $pos2->next;
    }

    $val = $pos1->data;
    $pos1->data = $pos2->data;
    $pos2->data = $val;
  }   

  //display the content of the list
  public function PrintList() {
    $temp = new Node();
    $temp = $this->head;
    if($temp != null) {
      echo "The list contains: ";
      while(true) {
        echo $temp->data." ";
        $temp = $temp->next;
        if($temp == $this->head)
          break;        
      }
      echo "\n";
    } else {
      echo "The list is empty.\n";
    }
  }    
};

// test the code  
$MyList = new LinkedList();

//Add five elements in the list.
$MyList->push_back(10);
$MyList->push_back(20);
$MyList->push_back(30);
$MyList->push_back(40);
$MyList->push_back(50);

//Display the content of the list.
$MyList->PrintList();

//swap values of node=1 and node=4
$MyList->swapNodeValues(1, 4);

//Display the content of the list.
$MyList->PrintList();
?>

The above code will give the following output: 

The list contains: 10 20 30 40 50 
The list contains: 40 20 30 10 50
AlphaCodingSkills
AlphaCodingSkills Android App
Facebook Page Twitter Page LinkedIn Page
Learning Tutorials
Learning Tutorials
Useful Links
Python Libraries
About Us  |  Privacy Policy  |  Contact Us
AlphaCodingSkills is a online learning portal that provides tutorials on Python, Java, C++, C, C#, PHP, R, Ruby, Rust, Scala, Swift, Perl, SQL, Data Structures and Algorithms. Tutorials, examples, references and content of the website are reviewed and simplified continuously to improve comprehensibility and eliminate any possible error. We use cookies to ensure best browsing experience on our website. While using this website, you acknowledge to have read and accepted our cookie and privacy policy.