Find the common nodes in two singly linked list

Given two linked list which consists similar type of node values. Our goal is to print all common node which is present in this linked list.

 Example A
 ---------
 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Output :  [3   8   -2   9]

 Example B
 ---------
 Linked List 1
 2 → 11 → 2 → 4 → NULL
 Linked List 2
 4 → 2 → 8 → 6 → -3 → NULL

 Output : [2  2  4]

That is an problems of linked list traversal, which is concurrent execute two linked list and test similar nodes. Given below solution is based on simple approach. Its take O(n^2) time.

// C Program 
// Find the common nodes in two singly linked list
#include <stdio.h>
#include <stdlib.h> //for malloc function

// Linked List LinkNode
struct LinkNode
{
	int data;
	struct LinkNode *next;
};
// Singly linked list 
struct SingleLL
{
	struct LinkNode *head;
	struct LinkNode *tail;
};
// Returns the new linked list
struct SingleLL *newLinkedList()
{
	// Create memory of head and tail Nodes
	struct SingleLL *sll = (struct SingleLL *) malloc(sizeof(struct SingleLL));
	if (sll == NULL)
	{
		printf("Memory overflow\n");
	}
	else
	{
		sll->head = NULL;
		sll->tail = NULL;
	}
	return sll;
}
// Add new Node at end of linked list 
void appendNode(struct SingleLL *sll, struct LinkNode *node)
{
	if (sll->head == NULL)
	{
		sll->head = node;
	}
	else
	{
		// Append the node at last position
		sll->tail->next = node;
	}
	sll->tail = node;
}
// Handles the request of adding new node in linked list
void addNode(struct SingleLL *sll, int data)
{
	// Create dynamic node
	struct LinkNode *node = (struct LinkNode *) malloc(sizeof(struct LinkNode));
	if (node == NULL)
	{
		printf("Memory overflow to Create LinkNode\n");
		return;
	}
	else
	{
		// Set initial node value
		node->data = data;
		node->next = NULL;
	}
	appendNode(sll, node);
}
// Display linked list element
void display(struct SingleLL *sll)
{
	if (sll->head == NULL)
	{
		printf("\n Empty linked list\n");
		return;
	}
	struct LinkNode *temp = sll->head;
	// iterating linked list elements
	while (temp != NULL)
	{
		printf(" %d →", temp->data);
		// Visit to next node
		temp = temp->next;
	}
	printf(" NULL\n");
}
// Find common nodes
void findCommonNodes(struct SingleLL *sll1, struct SingleLL *sll2)
{
	if (sll1->head == NULL || sll2->head == NULL)
	{
		return;
	}
	// Display linked list
	printf(" Linked List 1 \n");
	display(sll1);
	// Display linked list
	printf(" Linked List 2 \n");
	display(sll2);
	printf("\n Common Value \n");
	// Get first node of both linked list
	struct LinkNode *auxiliary = sll1->head;
	struct LinkNode *deviation = sll2->head;
	// Define some counter variables 
	int status = 0;
	int counter = 0;
	// iterating linked list elements
	while (auxiliary != NULL)
	{
		// Compare first linked list node to second linked list node value
		while (deviation != NULL)
		{
			if (deviation->data == auxiliary->data)
			{
				// Print common node
				printf("  %d ", auxiliary->data);
				// Like a break operation
				deviation = NULL;
				// Active state because we are got similar node
				status = 1;
				counter++;
			}
			else
			{
				// Visit to next node
				deviation = deviation->next;
			}
		}
		// Visit to next node
		auxiliary = auxiliary->next;
		// Reset second linked position
		// Start to first node of second linked list
		deviation = sll2->head;
	}
	if (status == 0)
	{
		// When no common node exists
		printf(" None \n");
	}
	else
	{
		printf("\n Total common element is : %d\n", counter);
	}
}
int main()
{
	struct SingleLL *sll1 = newLinkedList();
	struct SingleLL *sll2 = newLinkedList();
	// First linked list
	//  3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
	addNode(sll1, 3);
	addNode(sll1, 11);
	addNode(sll1, 8);
	addNode(sll1, 5);
	addNode(sll1, -2);
	addNode(sll1, 16);
	addNode(sll1, 9);
	// Second linked list
	//  4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
	addNode(sll2, 4);
	addNode(sll2, 9);
	addNode(sll2, 7);
	addNode(sll2, 3);
	addNode(sll2, 8);
	addNode(sll2, 6);
	addNode(sll2, -2);
	findCommonNodes(sll1, sll2);
	return 0;
}

Output

 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value
  3   8   -2   9
 Total common element is : 4
/*
  Java Program 
  Find the common nodes in two singly linked list
*/
// Linked list node
class LinkNode
{
    public int data;
    public LinkNode next;
    public LinkNode(int data)
    {
        this.data = data;
        this.next = null;
    }
}
public class SingleLL
{
    public LinkNode head;
    public LinkNode tail;
    public SingleLL()
    {
        this.head = null;
        this.tail = null;
    }
   
    // Add new Node at end of linked list 
    public void addNode(int data)
    {
        LinkNode node = new LinkNode(data);
        if (this.head == null)
        {
            this.head = node;
        }
        else
        {
            // Append the node at last position
            this.tail.next = node;
        }
        this.tail = node;
    }
    
    // Display linked list element
    public void display()
    {
        if (this.head == null)
        {
            System.out.print("\n Empty linked list\n");
            return;
        }
        LinkNode temp = this.head;
        //iterating linked list elements
        while (temp != null)
        {
            System.out.print(" " + temp.data + " →");
            // Visit to next node
            temp = temp.next;
        }
        System.out.print(" NULL\n");
    }
    // Find common nodes
    public void findCommonNodes(SingleLL second)
    {
        if (this.head == null || second.head == null)
        {
            return;
        }
        // Display linked list
        System.out.print(" Linked List 1 \n");
        this.display();
        // Display linked list
        System.out.print(" Linked List 2 \n");
        second.display();
        System.out.print("\n Common Value \n");
        // Get first node of both linked list
        LinkNode auxiliary = this.head;
        LinkNode deviation = second.head;
        // Define some counter variables 
        boolean status = false;
        int counter = 0;
        // iterating linked list elements
        while (auxiliary != null)
        {
            // Compare first linked list node to second linked list node value
            while (deviation != null)
            {
                if (deviation.data == auxiliary.data)
                {
                    // Print common node
                    System.out.print("  " + auxiliary.data );
                    // Like a break operation
                    deviation = null;
                    // Active state because we are got similar node
                    status = true;
                    // increase resultant count by 1
                    counter++;
                }
                else
                {
                    // Visit to next node
                    deviation = deviation.next;
                }
            }
            // Visit to next node
            auxiliary = auxiliary.next;
            // Reset second linked position
            // Start to first node of second linked list
            deviation = second.head;
        }
        if (status == false)
        {
            // When no common node exists
            System.out.print(" None \n");
        }
        else
        {
            System.out.print("\n Total common element is : " + counter + "\n");
        }
    }
   
    public static void main(String[] args)
    {
        SingleLL sll1 = new SingleLL();
        SingleLL sll2 = new SingleLL();
        // First linked list
        //  3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
        sll1.addNode(3);
        sll1.addNode(11);
        sll1.addNode(8);
        sll1.addNode(5);
        sll1.addNode(-2);
        sll1.addNode(16);
        sll1.addNode(9);
        // Second linked list
        //  4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
       sll2.addNode(4);
       sll2.addNode(9);
       sll2.addNode(7);
       sll2.addNode(3);
       sll2.addNode(8);
       sll2.addNode(6);
       sll2.addNode(-2);
       sll1.findCommonNodes(sll2);
    }
}

Output

 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value
  3  8  -2  9
 Total common element is : 4
// Include header file
#include <iostream>

using namespace std;
/*
  C++ Program 
  Find the common nodes in two singly linked list
*/
// Linked list node
class LinkNode
{
	public: int data;
	LinkNode *next;
	LinkNode(int data)
	{
		this->data = data;
		this->next = NULL;
	}
};
class SingleLL
{
	public: LinkNode *head;
	LinkNode *tail;
	SingleLL()
	{
		this->head = NULL;
		this->tail = NULL;
	}
	// Add new Node at end of linked list
	void addNode(int data)
	{
		LinkNode *node = new LinkNode(data);
		if (this->head == NULL)
		{
			this->head = node;
		}
		else
		{
			// Append the node at last position
			this->tail->next = node;
		}
		this->tail = node;
	}
	// Display linked list element
	void display()
	{
		if (this->head == NULL)
		{
			cout << "\n Empty linked list\n";
			return;
		}
		LinkNode *temp = this->head;
		//iterating linked list elements
		while (temp != NULL)
		{
			cout << " " << temp->data << " →";
			// Visit to next node
			temp = temp->next;
		}
		cout << " NULL\n";
	}
	// Find common nodes
	void findCommonNodes(SingleLL second)
	{
		if (this->head == NULL || second.head == NULL)
		{
			return;
		}
		// Display linked list
		cout << " Linked List 1 \n";
		this->display();
		// Display linked list
		cout << " Linked List 2 \n";
		second.display();
		cout << "\n Common Value \n";
		// Get first node of both linked list
		LinkNode *auxiliary = this->head;
		LinkNode *deviation = second.head;
		// Define some counter variables
		bool status = false;
		int counter = 0;
		// iterating linked list elements
		while (auxiliary != NULL)
		{
			// Compare first linked list node to second linked list node value
			while (deviation != NULL)
			{
				if (deviation->data == auxiliary->data)
				{
					// increase resultant count by 1
					// Print common node
					cout << "  " << auxiliary->data;
					// Like a break operation
					deviation = NULL;
					// Active state because we are got similar node
					status = true;
					counter++;
				}
				else
				{
					// Visit to next node
					deviation = deviation->next;
				}
			}
			// Visit to next node
			auxiliary = auxiliary->next;
			// Reset second linked position
			// Start to first node of second linked list
			deviation = second.head;
		}
		if (status == false)
		{
			// When no common node exists
			cout << " None \n";
		}
		else
		{
			cout << "\n Total common element is : " << counter << "\n";
		}
	}
};
int main()
{
	SingleLL sll1 = SingleLL();
	SingleLL sll2 = SingleLL();
	// First linked list
	//  3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
	sll1.addNode(3);
	sll1.addNode(11);
	sll1.addNode(8);
	sll1.addNode(5);
	sll1.addNode(-2);
	sll1.addNode(16);
	sll1.addNode(9);
	// Second linked list
	//  4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
	sll2.addNode(4);
	sll2.addNode(9);
	sll2.addNode(7);
	sll2.addNode(3);
	sll2.addNode(8);
	sll2.addNode(6);
	sll2.addNode(-2);
	sll1.findCommonNodes(sll2);
	return 0;
}

Output

 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value
  3  8  -2  9
 Total common element is : 4
// Include namespace system
using System;
/*
  C# Program 
  Find the common nodes in two singly linked list
*/
// Linked list node
public class LinkNode
{
	public int data;
	public LinkNode next;
	public LinkNode(int data)
	{
		this.data = data;
		this.next = null;
	}
}
public class SingleLL
{
	public LinkNode head;
	public LinkNode tail;
	public SingleLL()
	{
		this.head = null;
		this.tail = null;
	}
	// Add new Node at end of linked list
	public void addNode(int data)
	{
		LinkNode node = new LinkNode(data);
		if (this.head == null)
		{
			this.head = node;
		}
		else
		{
			// Append the node at last position
			this.tail.next = node;
		}
		this.tail = node;
	}
	// Display linked list element
	public void display()
	{
		if (this.head == null)
		{
			Console.Write("\n Empty linked list\n");
			return;
		}
		LinkNode temp = this.head;
		//iterating linked list elements
		while (temp != null)
		{
			Console.Write(" " + temp.data + " →");
			// Visit to next node
			temp = temp.next;
		}
		Console.Write(" NULL\n");
	}
	// Find common nodes
	public void findCommonNodes(SingleLL second)
	{
		if (this.head == null || second.head == null)
		{
			return;
		}
		// Display linked list
		Console.Write(" Linked List 1 \n");
		this.display();
		// Display linked list
		Console.Write(" Linked List 2 \n");
		second.display();
		Console.Write("\n Common Value \n");
		// Get first node of both linked list
		LinkNode auxiliary = this.head;
		LinkNode deviation = second.head;
		// Define some counter variables
		Boolean status = false;
		int counter = 0;
		// iterating linked list elements
		while (auxiliary != null)
		{
			// Compare first linked list node to second linked list node value
			while (deviation != null)
			{
				if (deviation.data == auxiliary.data)
				{
					// increase resultant count by 1
					// Print common node
					Console.Write("  " + auxiliary.data);
					// Like a break operation
					deviation = null;
					// Active state because we are got similar node
					status = true;
					counter++;
				}
				else
				{
					// Visit to next node
					deviation = deviation.next;
				}
			}
			// Visit to next node
			auxiliary = auxiliary.next;
			// Reset second linked position
			// Start to first node of second linked list
			deviation = second.head;
		}
		if (status == false)
		{
			// When no common node exists
			Console.Write(" None \n");
		}
		else
		{
			Console.Write("\n Total common element is : " + counter + "\n");
		}
	}
	public static void Main(String[] args)
	{
		SingleLL sll1 = new SingleLL();
		SingleLL sll2 = new SingleLL();
		// First linked list
		//  3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
		sll1.addNode(3);
		sll1.addNode(11);
		sll1.addNode(8);
		sll1.addNode(5);
		sll1.addNode(-2);
		sll1.addNode(16);
		sll1.addNode(9);
		// Second linked list
		//  4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
		sll2.addNode(4);
		sll2.addNode(9);
		sll2.addNode(7);
		sll2.addNode(3);
		sll2.addNode(8);
		sll2.addNode(6);
		sll2.addNode(-2);
		sll1.findCommonNodes(sll2);
	}
}

Output

 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value
  3  8  -2  9
 Total common element is : 4
<?php
/*
  Php Program 
  Find the common nodes in two singly linked list
*/
// Linked list node
class LinkNode
{
	public $data;
	public $next;

	function __construct($data)
	{
		$this->data = $data;
		$this->next = null;
	}
}
class SingleLL
{
	public $head;
	public $tail;

	function __construct()
	{
		$this->head = null;
		$this->tail = null;
	}
	// Add new Node at end of linked list
	public	function addNode($data)
	{
		$node = new LinkNode($data);
		if ($this->head == null)
		{
			$this->head = $node;
		}
		else
		{
			// Append the node at last position
			$this->tail->next = $node;
		}
		$this->tail = $node;
	}
	// Display linked list element
	public	function display()
	{
		if ($this->head == null)
		{
			echo "\n Empty linked list\n";
			return;
		}
		$temp = $this->head;
		//iterating linked list elements
		while ($temp != null)
		{
			echo " ". $temp->data ." →";
			// Visit to next node
			$temp = $temp->next;
		}
		echo " NULL\n";
	}
	// Find common nodes
	public	function findCommonNodes($second)
	{
		if ($this->head == null || $second->head == null)
		{
			return;
		}
		// Display linked list
		echo " Linked List 1 \n";
		$this->display();
		// Display linked list
		echo " Linked List 2 \n";
		$second->display();
		echo "\n Common Value \n";
		// Get first node of both linked list
		$auxiliary = $this->head;
		$deviation = $second->head;
		// Define some counter variables
		$status = false;
		$counter = 0;
		// iterating linked list elements
		while ($auxiliary != null)
		{
			// Compare first linked list node to second linked list node value
			while ($deviation != null)
			{
				if ($deviation->data == $auxiliary->data)
				{
					// increase resultant count by 1
					// Print common node
					echo "  ". $auxiliary->data;
					// Like a break operation
					$deviation = null;
					// Active state because we are got similar node
					$status = true;
					$counter++;
				}
				else
				{
					// Visit to next node
					$deviation = $deviation->next;
				}
			}
			// Visit to next node
			$auxiliary = $auxiliary->next;
			// Reset second linked position
			// Start to first node of second linked list
			$deviation = $second->head;
		}
		if ($status == false)
		{
			// When no common node exists
			echo " None \n";
		}
		else
		{
			echo "\n Total common element is : ". $counter ."\n";
		}
	}
}

function main()
{
	$sll1 = new SingleLL();
	$sll2 = new SingleLL();
	// First linked list
	//  3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
	$sll1->addNode(3);
	$sll1->addNode(11);
	$sll1->addNode(8);
	$sll1->addNode(5);
	$sll1->addNode(-2);
	$sll1->addNode(16);
	$sll1->addNode(9);
	// Second linked list
	//  4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
	$sll2->addNode(4);
	$sll2->addNode(9);
	$sll2->addNode(7);
	$sll2->addNode(3);
	$sll2->addNode(8);
	$sll2->addNode(6);
	$sll2->addNode(-2);
	$sll1->findCommonNodes($sll2);
}
main();

Output

 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value
  3  8  -2  9
 Total common element is : 4
/*
  Node Js Program 
  Find the common nodes in two singly linked list
*/
// Linked list node
class LinkNode
{
	constructor(data)
	{
		this.data = data;
		this.next = null;
	}
}
class SingleLL
{
	constructor()
	{
		this.head = null;
		this.tail = null;
	}
	// Add new Node at end of linked list
	addNode(data)
	{
		var node = new LinkNode(data);
		if (this.head == null)
		{
			this.head = node;
		}
		else
		{
			// Append the node at last position
			this.tail.next = node;
		}
		this.tail = node;
	}
	// Display linked list element
	display()
	{
		if (this.head == null)
		{
			process.stdout.write("\n Empty linked list\n");
			return;
		}
		var temp = this.head;
		//iterating linked list elements
		while (temp != null)
		{
			process.stdout.write(" " + temp.data + " →");
			// Visit to next node
			temp = temp.next;
		}
		process.stdout.write(" NULL\n");
	}
	// Find common nodes
	findCommonNodes(second)
	{
		if (this.head == null || second.head == null)
		{
			return;
		}
		// Display linked list
		process.stdout.write(" Linked List 1 \n");
		this.display();
		// Display linked list
		process.stdout.write(" Linked List 2 \n");
		second.display();
		process.stdout.write("\n Common Value \n");
		// Get first node of both linked list
		var auxiliary = this.head;
		var deviation = second.head;
		// Define some counter variables
		var status = false;
		var counter = 0;
		// iterating linked list elements
		while (auxiliary != null)
		{
			// Compare first linked list node to second linked list node value
			while (deviation != null)
			{
				if (deviation.data == auxiliary.data)
				{
					// increase resultant count by 1
					// Print common node
					process.stdout.write("  " + auxiliary.data);
					// Like a break operation
					deviation = null;
					// Active state because we are got similar node
					status = true;
					counter++;
				}
				else
				{
					// Visit to next node
					deviation = deviation.next;
				}
			}
			// Visit to next node
			auxiliary = auxiliary.next;
			// Reset second linked position
			// Start to first node of second linked list
			deviation = second.head;
		}
		if (status == false)
		{
			// When no common node exists
			process.stdout.write(" None \n");
		}
		else
		{
			process.stdout.write("\n Total common element is : " + counter + "\n");
		}
	}
}

function main()
{
	var sll1 = new SingleLL();
	var sll2 = new SingleLL();
	// First linked list
	//  3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
	sll1.addNode(3);
	sll1.addNode(11);
	sll1.addNode(8);
	sll1.addNode(5);
	sll1.addNode(-2);
	sll1.addNode(16);
	sll1.addNode(9);
	// Second linked list
	//  4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
	sll2.addNode(4);
	sll2.addNode(9);
	sll2.addNode(7);
	sll2.addNode(3);
	sll2.addNode(8);
	sll2.addNode(6);
	sll2.addNode(-2);
	sll1.findCommonNodes(sll2);
}
main();

Output

 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value
  3  8  -2  9
 Total common element is : 4
#   Python 3 Program 
#   Find the common nodes in two singly linked list

#  Linked list node
class LinkNode :
	
	def __init__(self, data) :
		self.data = data
		self.next = None
	

class SingleLL :
	
	def __init__(self) :
		self.head = None
		self.tail = None
	
	#  Add new Node at end of linked list 
	def addNode(self, data) :
		node = LinkNode(data)
		if (self.head == None) :
			self.head = node
		else :
			#  Append the node at last position
			self.tail.next = node
		
		self.tail = node
	
	#  Display linked list element
	def display(self) :
		if (self.head == None) :
			print("\n Empty linked list")
			return
		
		temp = self.head
		# iterating linked list elements
		while (temp != None) :
			print("", temp.data ,"→", end = "")
			#  Visit to next node
			temp = temp.next
		
		print(" NULL")
	
	#  Find common nodes
	def findCommonNodes(self, second) :
		if (self.head == None or second.head == None) :
			return
		
		#  Display linked list
		print(" Linked List 1 ")
		self.display()
		#  Display linked list
		print(" Linked List 2 ")
		second.display()
		print("\n Common Value ")
		#  Get first node of both linked list
		auxiliary = self.head
		deviation = second.head
		#  Define some counter variables 
		status = False
		counter = 0
		#  iterating linked list elements
		while (auxiliary != None) :
			#  Compare first linked list node to second linked list node value
			while (deviation != None) :
				if (deviation.data == auxiliary.data) :
					#  Print common node
					print("  ", auxiliary.data, end = "")
					#  Like a break operation
					deviation = None
					#  Active state because we are got similar node
					status = True
					#  increase resultant count by 1
					counter += 1
				else :
					#  Visit to next node
					deviation = deviation.next
				
			
			#  Visit to next node
			auxiliary = auxiliary.next
			#  Reset second linked position
			#  Start to first node of second linked list
			deviation = second.head
		
		if (status == False) :
			#  When no common node exists
			print(" None ")
		else :
			print("\n Total common element is : ", counter )
		
	

def main() :
	sll1 = SingleLL()
	sll2 = SingleLL()
	#  First linked list
	#   3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
	sll1.addNode(3)
	sll1.addNode(11)
	sll1.addNode(8)
	sll1.addNode(5)
	sll1.addNode(-2)
	sll1.addNode(16)
	sll1.addNode(9)
	#  Second linked list
	#   4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
	sll2.addNode(4)
	sll2.addNode(9)
	sll2.addNode(7)
	sll2.addNode(3)
	sll2.addNode(8)
	sll2.addNode(6)
	sll2.addNode(-2)
	sll1.findCommonNodes(sll2)

if __name__ == "__main__": main()

Output

 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value
   3   8   -2   9
 Total common element is :  4
#   Ruby Program 
#   Find the common nodes in two singly linked list

#  Linked list node
class LinkNode  
	# Define the accessor and reader of class LinkNode  
	attr_reader :data, :next
	attr_accessor :data, :next
 
	
	def initialize(data) 
		self.data = data
		self.next = nil
	end

end

class SingleLL  
	# Define the accessor and reader of class SingleLL  
	attr_reader :head, :tail
	attr_accessor :head, :tail
 
	
	def initialize() 
		self.head = nil
		self.tail = nil
	end

	#  Add new Node at end of linked list 
	def addNode(data) 
		node = LinkNode.new(data)
		if (self.head == nil) 
			self.head = node
		else 
			#  Append the node at last position
			self.tail.next = node
		end

		self.tail = node
	end

	#  Display linked list element
	def display() 
		if (self.head == nil) 
			print("\n Empty linked list\n")
			return
		end

		temp = self.head
		# iterating linked list elements
		while (temp != nil) 
			print(" ", temp.data ," →")
			#  Visit to next node
			temp = temp.next
		end

		print(" NULL\n")
	end

	#  Find common nodes
	def findCommonNodes(second) 
		if (self.head == nil || second.head == nil) 
			return
		end

		#  Display linked list
		print(" Linked List 1 \n")
		self.display()
		#  Display linked list
		print(" Linked List 2 \n")
		second.display()
		print("\n Common Value \n")
		#  Get first node of both linked list
		auxiliary = self.head
		deviation = second.head
		#  Define some counter variables 
		status = false
		counter = 0
		#  iterating linked list elements
		while (auxiliary != nil) 
			#  Compare first linked list node to second linked list node value
			while (deviation != nil) 
				if (deviation.data == auxiliary.data) 
					#  Print common node
					print("  ", auxiliary.data)
					#  Like a break operation
					deviation = nil
					#  Active state because we are got similar node
					status = true
					#  increase resultant count by 1
					counter += 1
				else 
					#  Visit to next node
					deviation = deviation.next
				end

			end

			#  Visit to next node
			auxiliary = auxiliary.next
			#  Reset second linked position
			#  Start to first node of second linked list
			deviation = second.head
		end

		if (status == false) 
			#  When no common node exists
			print(" None \n")
		else 
			print("\n Total common element is : ", counter ,"\n")
		end

	end

end

def main() 
	sll1 = SingleLL.new()
	sll2 = SingleLL.new()
	#  First linked list
	#   3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
	sll1.addNode(3)
	sll1.addNode(11)
	sll1.addNode(8)
	sll1.addNode(5)
	sll1.addNode(-2)
	sll1.addNode(16)
	sll1.addNode(9)
	#  Second linked list
	#   4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
	sll2.addNode(4)
	sll2.addNode(9)
	sll2.addNode(7)
	sll2.addNode(3)
	sll2.addNode(8)
	sll2.addNode(6)
	sll2.addNode(-2)
	sll1.findCommonNodes(sll2)
end

main()

Output

 Linked List 1 
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2 
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value 
  3  8  -2  9
 Total common element is : 4
/*
  Scala Program 
  Find the common nodes in two singly linked list
*/
// Linked list node
class LinkNode(var data: Int , var next: LinkNode)
{
	def this(data: Int)
	{
		this(data, null);
	}
}
class SingleLL(var head: LinkNode , var tail: LinkNode)
{
	def this()
	{
		this(null, null);
	}
	// Add new Node at end of linked list
	def addNode(data: Int): Unit = {
		var node: LinkNode = new LinkNode(data);
		if (this.head == null)
		{
			this.head = node;
		}
		else
		{
			// Append the node at last position
			this.tail.next = node;
		}
		this.tail = node;
	}
	// Display linked list element
	def display(): Unit = {
		if (this.head == null)
		{
			print("\n Empty linked list\n");
			return;
		}
		var temp: LinkNode = this.head;
		//iterating linked list elements
		while (temp != null)
		{
			print(" " + temp.data + " →");
			// Visit to next node
			temp = temp.next;
		}
		print(" NULL\n");
	}
	// Find common nodes
	def findCommonNodes(second: SingleLL): Unit = {
		if (this.head == null || second.head == null)
		{
			return;
		}
		// Display linked list
		print(" Linked List 1 \n");
		this.display();
		// Display linked list
		print(" Linked List 2 \n");
		second.display();
		print("\n Common Value \n");
		// Get first node of both linked list
		var auxiliary: LinkNode = this.head;
		var deviation: LinkNode = second.head;
		// Define some counter variables
		var status: Boolean = false;
		var counter: Int = 0;
		// iterating linked list elements
		while (auxiliary != null)
		{
			// Compare first linked list node to second linked list node value
			while (deviation != null)
			{
				if (deviation.data == auxiliary.data)
				{
					// increase resultant count by 1
					// Print common node
					print("  " + auxiliary.data);
					// Like a break operation
					deviation = null;
					// Active state because we are got similar node
					status = true;
					counter += 1;
				}
				else
				{
					// Visit to next node
					deviation = deviation.next;
				}
			}
			// Visit to next node
			auxiliary = auxiliary.next;
			// Reset second linked position
			// Start to first node of second linked list
			deviation = second.head;
		}
		if (status == false)
		{
			// When no common node exists
			print(" None \n");
		}
		else
		{
			print("\n Total common element is : " + counter + "\n");
		}
	}
}
object Main
{
	def main(args: Array[String]): Unit = {
		var sll1: SingleLL = new SingleLL();
		var sll2: SingleLL = new SingleLL();
		// First linked list
		//  3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
		sll1.addNode(3);
		sll1.addNode(11);
		sll1.addNode(8);
		sll1.addNode(5);
		sll1.addNode(-2);
		sll1.addNode(16);
		sll1.addNode(9);
		// Second linked list
		//  4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
		sll2.addNode(4);
		sll2.addNode(9);
		sll2.addNode(7);
		sll2.addNode(3);
		sll2.addNode(8);
		sll2.addNode(6);
		sll2.addNode(-2);
		sll1.findCommonNodes(sll2);
	}
}

Output

 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value
  3  8  -2  9
 Total common element is : 4
/*
  Swift 4 Program 
  Find the common nodes in two singly linked list
*/
// Linked list node
class LinkNode
{
	var data: Int;
	var next: LinkNode? ;
	init(_ data: Int)
	{
		self.data = data;
		self.next = nil;
	}
}
class SingleLL
{
	var head: LinkNode? ;
	var tail: LinkNode? ;
	init()
	{
		self.head = nil;
		self.tail = nil;
	}
	// Add new Node at end of linked list
	func addNode(_ data: Int)
	{
		let node: LinkNode? = LinkNode(data);
		if (self.head == nil)
		{
			self.head = node;
		}
		else
		{
			// Append the node at last position
			self.tail!.next = node;
		}
		self.tail = node;
	}
	// Display linked list element
	func display()
	{
		if (self.head == nil)
		{
			print("\n Empty linked list");
			return;
		}
		var temp: LinkNode? = self.head;
		//iterating linked list elements
		while (temp  != nil)
		{
			print("", temp!.data ,"→", terminator: "");
			// Visit to next node
			temp = temp!.next;
		}
		print(" NULL");
	}
	// Find common nodes
	func findCommonNodes(_ second: SingleLL)
	{
		if (self.head == nil || second.head == nil)
		{
			return;
		}
		// Display linked list
		print(" Linked List 1 ");
		self.display();
		// Display linked list
		print(" Linked List 2 ");
		second.display();
		print("\n Common Value ");
		// Get first node of both linked list
		var auxiliary: LinkNode? = self.head;
		var deviation: LinkNode? = second.head;
		// Define some counter variables
		var status: Bool = false;
		var counter: Int = 0;
		// iterating linked list elements
		while (auxiliary  != nil)
		{
			// Compare first linked list node to second linked list node value
			while (deviation  != nil)
			{
				if (deviation!.data == auxiliary!.data)
				{
					// increase resultant count by 1
					// Print common node
					print("  ", auxiliary!.data, terminator: "");
					// Like a break operation
					deviation = nil;
					// Active state because we are got similar node
					status = true;
					counter += 1;
				}
				else
				{
					// Visit to next node
					deviation = deviation!.next;
				}
			}
			// Visit to next node
			auxiliary = auxiliary!.next;
			// Reset second linked position
			// Start to first node of second linked list
			deviation = second.head;
		}
		if (status == false)
		{
			// When no common node exists
			print(" None ");
		}
		else
		{
			print("\n Total common element is : ", counter );
		}
	}
}
func main()
{
	let sll1: SingleLL = SingleLL();
	let sll2: SingleLL = SingleLL();
	// First linked list
	//  3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
	sll1.addNode(3);
	sll1.addNode(11);
	sll1.addNode(8);
	sll1.addNode(5);
	sll1.addNode(-2);
	sll1.addNode(16);
	sll1.addNode(9);
	// Second linked list
	//  4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
	sll2.addNode(4);
	sll2.addNode(9);
	sll2.addNode(7);
	sll2.addNode(3);
	sll2.addNode(8);
	sll2.addNode(6);
	sll2.addNode(-2);
	sll1.findCommonNodes(sll2);
}
main();

Output

 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value
   3   8   -2   9
 Total common element is :  4
/*
  Kotlin Program 
  Find the common nodes in two singly linked list
*/
// Linked list node
class LinkNode
{
	var data: Int;
	var next: LinkNode ? ;
	constructor(data: Int)
	{
		this.data = data;
		this.next = null;
	}
}
class SingleLL
{
	var head: LinkNode ? ;
	var tail: LinkNode ? ;
	constructor()
	{
		this.head = null;
		this.tail = null;
	}
	// Add new Node at end of linked list
	fun addNode(data: Int): Unit
	{
		var node: LinkNode = LinkNode(data);
		if (this.head == null)
		{
			this.head = node;
		}
		else
		{
			// Append the node at last position
			this.tail?.next = node;
		}
		this.tail = node;
	}
	// Display linked list element
	fun display(): Unit
	{
		if (this.head == null)
		{
			print("\n Empty linked list\n");
			return;
		}
		var temp: LinkNode ? = this.head;
		//iterating linked list elements
		while (temp != null)
		{
			print(" " + temp.data + " →");
			// Visit to next node
			temp = temp.next;
		}
		print(" NULL\n");
	}
	// Find common nodes
	fun findCommonNodes(second: SingleLL): Unit
	{
		if (this.head == null || second.head == null)
		{
			return;
		}
		// Display linked list
		print(" Linked List 1 \n");
		this.display();
		// Display linked list
		print(" Linked List 2 \n");
		second.display();
		print("\n Common Value \n");
		// Get first node of both linked list
		var auxiliary: LinkNode ? = this.head;
		var deviation: LinkNode ? = second.head;
		// Define some counter variables
		var status: Boolean = false;
		var counter: Int = 0;
		// iterating linked list elements
		while (auxiliary != null)
		{
			// Compare first linked list node to second linked list node value
			while (deviation != null)
			{
				if (deviation.data == auxiliary.data)
				{
					// increase resultant count by 1
					// Print common node
					print("  " + auxiliary.data);
					// Like a break operation
					deviation = null;
					// Active state because we are got similar node
					status = true;
					counter += 1;
				}
				else
				{
					// Visit to next node
					deviation = deviation.next;
				}
			}
			// Visit to next node
			auxiliary = auxiliary.next;
			// Reset second linked position
			// Start to first node of second linked list
			deviation = second.head;
		}
		if (status == false)
		{
			// When no common node exists
			print(" None \n");
		}
		else
		{
			print("\n Total common element is : " + counter + "\n");
		}
	}
}
fun main(args: Array < String > ): Unit
{
	var sll1: SingleLL = SingleLL();
	var sll2: SingleLL = SingleLL();
	// First linked list
	//  3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
	sll1.addNode(3);
	sll1.addNode(11);
	sll1.addNode(8);
	sll1.addNode(5);
	sll1.addNode(-2);
	sll1.addNode(16);
	sll1.addNode(9);
	// Second linked list
	//  4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL
	sll2.addNode(4);
	sll2.addNode(9);
	sll2.addNode(7);
	sll2.addNode(3);
	sll2.addNode(8);
	sll2.addNode(6);
	sll2.addNode(-2);
	sll1.findCommonNodes(sll2);
}

Output

 Linked List 1
 3 → 11 → 8 → 5 → -2 → 16 → 9 → NULL
 Linked List 2
 4 → 9 → 7 → 3 → 8 → 6 → -2 → NULL

 Common Value
  3  8  -2  9
 Total common element is : 4


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