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Program to swap nodes in a singly linked list without swapping dataExplanationIn this program, we need to swap given two nodes in the singly linked list without swapping data. One of the approaches to accomplish this task is to swap the previous nodes of the given two nodes and then, swap the next nodes of two nodes. Algorithm
SolutionPython#Represent a node of the singly linked list class Node: def __init__(self,data): self.data = data; self.next = None; class SwapNodes: #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; #swap() will swap the given two nodes def swap(self, n1, n2): prevNode1 = None; prevNode2 = None; node1 = self.head; node2 = self.head; #Checks if list is empty if(self.head == None): return; #If n1 and n2 are equal, then list will remain the same if(n1 == n2): return; #Search for node1 while(node1 != None and node1.data != n1): prevNode1 = node1; node1 = node1.next; #Search for node2 while(node2 != None and node2.data != n2): prevNode2 = node2; node2 = node2.next; if(node1 != None and node2 != None): #If previous node to node1 is not None then, it will point to node2 if(prevNode1 != None): prevNode1.next = node2; else: self.head = node2; #If previous node to node2 is not None then, it will point to node1 if(prevNode2 != None): prevNode2.next = node1; else: self.head = node1; #Swaps the next nodes of node1 and node2 temp = node1.next; node1.next = node2.next; node2.next = temp; else: print("Swapping is not possible"); #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; sList = SwapNodes(); #Add nodes to the list sList.addNode(1); sList.addNode(2); sList.addNode(3); sList.addNode(4); sList.addNode(5); print("Original list: "); sList.display(); #Swaps the node 2 with node 5 sList.swap(2,5); print("List after swapping nodes: "); sList.display(); Output: Original list: 1 2 3 4 5 List after swapping nodes: 1 5 3 4 2 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; } } //swap() will swap the given two nodes void swap(int n1, int n2){ struct node *prevNode1 = NULL, *prevNode2 = NULL, *node1 = head, *node2 = head, *temp = NULL; //Checks if list is empty if(head == NULL) { return; } //If n1 and n2 are equal, then list will remain the same if(n1 == n2) return; //Search for node1 while(node1 != NULL && node1>data != n1){ prevNode1 = node1; node1 = node1>next; } //Search for node2 while(node2 != NULL && node2>data != n2){ prevNode2 = node2; node2 = node2>next; } if(node1 != NULL && node2 != NULL) { //If previous node to node1 is not null then, it will point to node2 if(prevNode1 != NULL) prevNode1>next = node2; else head = node2; //If previous node to node2 is not null then, it will point to node1 if(prevNode2 != NULL) prevNode2>next = node1; else head = node1; //Swaps the next nodes of node1 and node2 temp = node1>next; node1>next = node2>next; node2>next = temp; } else{ printf("Swapping is not possible\n"); } } //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() { //Add nodes to the list addNode(1); addNode(2); addNode(3); addNode(4); addNode(5); printf("Original list: \n"); display(); //Swaps the node 2 with node 5 swap(2,5); printf("List after swapping nodes: \n"); display(); return 0; } Output: Original list: 1 2 3 4 5 List after swapping nodes: 1 5 3 4 2 JAVApublic class SwapNodes { //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; } } //swap() will swap the given two nodes public void swap(int n1, int n2){ Node prevNode1 = null, prevNode2 = null, node1 = head, node2 = head; //Checks if list is empty if(head == null) { return; } //If n1 and n2 are equal, then list will remain the same if(n1 == n2) return; //Search for node1 while(node1 != null && node1.data != n1){ prevNode1 = node1; node1 = node1.next; } //Search for node2 while(node2 != null && node2.data != n2){ prevNode2 = node2; node2 = node2.next; } if(node1 != null && node2 != null) { //If previous node to node1 is not null then, it will point to node2 if(prevNode1 != null) prevNode1.next = node2; else head = node2; //If previous node to node2 is not null then, it will point to node1 if(prevNode2 != null) prevNode2.next = node1; else head = node1; //Swaps the next nodes of node1 and node2 Node temp = node1.next; node1.next = node2.next; node2.next = temp; } else { System.out.println("Swapping is not possible"); } } //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) { SwapNodes sList = new SwapNodes(); //Add nodes to the list sList.addNode(1); sList.addNode(2); sList.addNode(3); sList.addNode(4); sList.addNode(5); System.out.println("Original list: "); sList.display(); //Swaps the node 2 with node 5 sList.swap(2,5); System.out.println("List after swapping nodes: "); sList.display(); } } Output: Original list: 1 2 3 4 5 List after swapping nodes: 1 5 3 4 2 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 SwapNodes<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; } } //swap() will swap the given two nodes public void swap(int n1, int n2){ Node<T> prevNode1 = null, prevNode2 = null, node1 = head, node2 = head; //Checks if list is empty if(head == null) { return; } //If n1 and n2 are equal, then list will remain the same if(n1 == n2) return; //Search for node1 while(node1 != null && !(node1.data.Equals(n1))){ prevNode1 = node1; node1 = node1.next; } //Search for node2 while(node2 != null && !(node2.data.Equals(n2))){ prevNode2 = node2; node2 = node2.next; } if(node1 != null && node2 != null) { //If previous node to node1 is not null then, it will point to node2 if(prevNode1 != null) prevNode1.next = node2; else head = node2; //If previous node to node2 is not null then, it will point to node1 if(prevNode2 != null) prevNode2.next = node1; else head = node1; //Swaps the next nodes of node1 and node2 Node<T> temp = node1.next; node1.next = node2.next; node2.next = temp; } else { Console.WriteLine("Swapping is not possible"); } } //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() { SwapNodes<int> sList = new SwapNodes<int>(); //Add nodes to the list sList.addNode(1); sList.addNode(2); sList.addNode(3); sList.addNode(4); sList.addNode(5); Console.WriteLine("Original list: "); sList.display(); //Swaps the node 2 with node 5 sList.swap(2,5); Console.WriteLine("List after swapping nodes: "); sList.display(); } } Output: Original list: 1 2 3 4 5 List after swapping nodes: 1 5 3 4 2 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 SwapNodes{ //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 = $newNode; } } //swap() will swap the given two nodes function swap($n1, $n2){ $prevNode1 = null; $prevNode2 = null; $node1 = $this>head; $node2 = $this>head; //Checks if list is empty if($this>head == null) { return; } //If n1 and n2 are equal, then list will remain the same if($n1 == $n2) return; //Search for node1 while($node1 != null && $node1>data != $n1){ $prevNode1 = $node1; $node1 = $node1>next; } //Search for node2 while($node2 != null && $node2>data != $n2){ $prevNode2 = $node2; $node2 = $node2>next; } if($node1 != null && $node2 != null) { //If previous node to node1 is not null then, it will point to node2 if($prevNode1 != null) $prevNode1>next = $node2; else $this>head = $node2; //If previous node to node2 is not null then, it will point to node1 if($prevNode2 != null) $prevNode2>next = $node1; else $this>head = $node1; //Swaps the next nodes of node1 and node2 $temp = $node1>next; $node1>next = $node2>next; $node2>next = $temp; } else { print("Swapping is not possible <br>"); } } //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 SwapNodes(); //Add nodes to the list $sList>addNode(1); $sList>addNode(2); $sList>addNode(3); $sList>addNode(4); $sList>addNode(5); print("Original list: <br>"); $sList>display(); //Swaps the node 2 with node 5 $sList>swap(2,5); print("List after swapping nodes: <br>"); $sList>display(); ?> </body> </html> Output: Original list: 1 2 3 4 5 List after swapping nodes: 1 5 3 4 2
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