Find middle element in doubly linked list

Find middle node in doubly linked list

Here given code implementation process.

//C Program
//Find middle element in doubly linked list
#include <stdio.h>

#include <stdlib.h> //for malloc function

//create structure
struct Node {
  int data;
  struct Node *next;
  struct Node *prev;
};


//head and tail pointers
struct Node *head = NULL, *tail = NULL;

//insert Node element of end of linked list
void insert(int value) {

  //Create a dynamic Node
  struct Node *node = (struct Node *) malloc(sizeof(struct Node));
  if (node == NULL) {
    printf("Memory overflow\n");
  } else {
    //set data value
    node->data = value;
    node->next = NULL;
    node->prev = NULL;
    if (head == NULL) {
      head = node;
      tail = node;

    } else {
      node->prev = tail;
      tail->next = node;

      tail = node;

    }
  }
}
//display element of Node
void display() {
  struct Node *temp = head;
  if (temp == NULL) {
    printf("Empty linked list");
  } else {

    printf("\n Head to Tail Nodes : \n");
    //Traverse doubly linked list from front to rear
    while (temp != NULL) {
      //print Node value
      printf("%3d", temp->data);
      temp = temp->next;
    }
    printf("\n Tail to Head Nodes : \n");

    temp = tail;

    //Traverse doubly linked list from rear to front
    while (temp != NULL) {
      //print Node value
      printf("%3d", temp->data);
      temp = temp->prev;
    }
  }

}
///find mid node
void  middle_node()
{
  if(head!=NULL)

  {

    struct Node*slow=head,*fast=head;

    while(fast!=NULL && fast->next != NULL && fast->next->next != NULL)
    {
      slow = slow->next;
      fast = fast->next->next;
    }
    printf("\n Middle : %d\n",slow->data);


  }else
  {
    //when linked list is empty
    printf("Empty linked list");

  }
}

int main() {

  //Insert element of linked list
  insert(1);
  insert(2);
  insert(3);
  insert(4);
  insert(5);
  insert(6);
  //Display all node
  display();

  middle_node();

  insert(7);
  display();
  middle_node();
  printf("\n");
  return 0;
}

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6
 Tail to Head Nodes : 
  6  5  4  3  2  1
 Middle : 3

 Head to Tail Nodes : 
  1  2  3  4  5  6  7
 Tail to Head Nodes : 
  7  6  5  4  3  2  1
 Middle : 4
/*
 C++ Program
 Find middle element in doubly linked list
*/

#include<iostream>

using namespace std;
class Node {
  public:
    int data;
  Node *next;
  Node *prev;
  Node(int value) {
    this->data = value;
    this->next = NULL;
    this->prev = NULL;
  }
};
class LinkedList {
  public:
    Node *head;
  Node *tail;
  LinkedList() {
    this->head = NULL;
    this->tail = NULL;
  }
  void insert(int value) {
    Node *node = new Node(value);
    if (node == NULL) {
      cout << "Memory overflow\n";
      return;
    }
    if (this->head == NULL) {
      this->head = node;
      this->tail = node;
    } else {
      node->prev = this->tail;
      this->tail->next = node;
      this->tail = node;
    }
  }
  void display() {
    Node *temp = this->head;
    if (temp == NULL) {
      cout << "\nEmpty linked list\n";
      return;
    }
    cout << "\n Head to Tail Nodes : \n  ";
    while (temp != NULL) {
      cout << temp->data << "  ";
      temp = temp->next;
    }
    temp = this->tail;
    cout << "\n Tail to Head Nodes : \n  ";
    while (temp != NULL) {
      cout << temp->data << "  ";
      temp = temp->prev;
    }
  }
  void middle_node() {
    if (this->head != NULL) {
      Node *slow = this->head, *fast = this->head;
      while (fast != NULL && fast->next != NULL && fast->next->next != NULL) {
        slow = slow->next;
        fast = fast->next->next;
      }
      cout << "\n Middle : " << slow->data << "\n";
    } else {
      cout << "Empty linked list";
    }
  }
};
int main() {
  LinkedList obj;
  obj.insert(1);
  obj.insert(2);
  obj.insert(3);
  obj.insert(4);
  obj.insert(5);
  obj.insert(6);
  obj.display();
  obj.middle_node();
  obj.insert(7);
  obj.display();
  obj.middle_node();
  return 0;
}

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6
 Tail to Head Nodes : 
  6  5  4  3  2  1
 Middle : 3

 Head to Tail Nodes : 
  1  2  3  4  5  6  7
 Tail to Head Nodes : 
  7  6  5  4  3  2  1
 Middle : 4
/*
  Java Program
  Find middle element in doubly linked list

*/
class Node {

  public int data;

  public Node next;

  public Node prev;

  public Node(int value) {
    //Setup initial values of linked list node
    this.data = value;
    this.next = null;
    this.prev = null;
  }
}
class LinkedList {

  public Node head;
  public Node tail;

  public LinkedList() {
    head = null;
    tail = null;
  }
  public void insert(int value) {
    Node node = new Node(value);

    if (node == null) {

      System.out.print("Memory overflow\n");
      return;
    }
    if (head == null) {
      head = node;
      tail = node;
    } else {
      //Add Node at the end of linked list
      node.prev = tail;
      tail.next = node;
      tail = node;
    }
  }



  public void display() {
    Node temp = head;
    if (temp == null) {
      System.out.print("\nEmpty linked list\n");
      return;
    }

    System.out.print("\n Head to Tail Nodes : \n  ");

    while (temp != null) {
      System.out.print(temp.data + "  ");
      temp = temp.next;
    }

    temp = tail;

    System.out.print("\n Tail to Head Nodes : \n  ");

    while (temp != null) {
      System.out.print(temp.data + "  ");
      temp = temp.prev;
    }

  }
  //Find out middle node 
  public void middle_node() {

    if (head != null) {
      Node slow = head, fast = head;

      while (fast != null && fast.next != null && fast.next.next != null) {
        slow = slow.next;
        fast = fast.next.next;
      }

      System.out.print("\n Middle : " + slow.data+ "\n");
    } else {

      System.out.print("Empty linked list");
    }
  }




  public static void main(String[] args) {
    LinkedList obj = new LinkedList();
    //Insert element of linked list
    obj.insert(1);
    obj.insert(2);
    obj.insert(3);
    obj.insert(4);
    obj.insert(5);
    obj.insert(6);
    //Display all node
    obj.display();

    obj.middle_node();

    obj.insert(7);
    obj.display();
    obj.middle_node();
   
  }


}

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6
 Tail to Head Nodes : 
  6  5  4  3  2  1
 Middle : 3

 Head to Tail Nodes : 
  1  2  3  4  5  6  7
 Tail to Head Nodes : 
  7  6  5  4  3  2  1
 Middle : 4
/*
  C# Program
  Find middle element in doubly linked list

*/
using System;
public class Node {

	public int data;

	public Node next;

	public Node prev;

	public Node(int value) {
		//Setup initial values of linked list node
		this.data = value;
		this.next = null;
		this.prev = null;
	}
}
class LinkedList {

	public Node head;
	public Node tail;

	public LinkedList() {
		head = null;
		tail = null;
	}
	public void insert(int value) {
		Node node = new Node(value);

		if (node == null) {

			Console.Write("Memory overflow\n");
			return;
		}
		if (head == null) {
			head = node;
			tail = node;
		} else {
			//Add Node at the end of linked list
			node.prev = tail;
			tail.next = node;
			tail = node;
		}
	}



	public void display() {
		Node temp = head;
		if (temp == null) {
			Console.Write("\nEmpty linked list\n");
			return;
		}

		Console.Write("\n Head to Tail Nodes : \n  ");

		while (temp != null) {
			Console.Write(temp.data + "  ");
			temp = temp.next;
		}

		temp = tail;

		Console.Write("\n Tail to Head Nodes : \n  ");

		while (temp != null) {
			Console.Write(temp.data + "  ");
			temp = temp.prev;
		}

	}
	//Find out middle node 
	public void middle_node() {

		if (head != null) {
			Node slow = head, fast = head;

			while (fast != null && fast.next != null && fast.next.next != null) {
				slow = slow.next;
				fast = fast.next.next;
			}

			Console.Write("\n Middle : " + slow.data+ "\n");
		} else {

			Console.Write("Empty linked list");
		}
	}




	public static void Main(String[] args) {
		LinkedList obj = new LinkedList();
		//Insert element of linked list
		obj.insert(1);
		obj.insert(2);
		obj.insert(3);
		obj.insert(4);
		obj.insert(5);
		obj.insert(6);
		//Display all node
		obj.display();

		obj.middle_node();

		obj.insert(7);
		obj.display();
		obj.middle_node();

	}


}

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6
 Tail to Head Nodes : 
  6  5  4  3  2  1
 Middle : 3

 Head to Tail Nodes : 
  1  2  3  4  5  6  7
 Tail to Head Nodes : 
  7  6  5  4  3  2  1
 Middle : 4
# Python 3 Program
# Find middle element in doubly linked list

class Node :

  def __init__(self, value) :
    self.data = value
    self.next = None
    self.prev = None
  

class LinkedList :

  def __init__(self) :
    self.head = None
    self.tail = None
  
  def insert(self, value) :
    node = Node(value)
    if (node == None) :
      print("Memory overflow\n")
      return
    
    if (self.head == None) :
      self.head = node
      self.tail = node
    else :
      node.prev = self.tail
      self.tail.next = node
      self.tail = node
    
  
  def display(self) :
    temp = self.head
    if (temp == None) :
      print("\nEmpty linked list")
      return
    
    print("\n Head to Tail Nodes :  ")
    while (temp != None) :
      print(temp.data ,end="  ")
      temp = temp.next
    
    temp = self.tail
    print("\n Tail to Head Nodes :  ")
    while (temp != None) :
      print(temp.data ,end="  ")
      temp = temp.prev
    
  
  def middle_node(self) :
    if (self.head != None) :
      slow = self.head
      fast = self.head
      while (fast != None and fast.next != None and fast.next.next != None) :
        slow = slow.next
        fast = fast.next.next
      
      print("\n Middle : ", slow.data )
    else :
      print("Empty linked list")
    
  

def main() :
  obj = LinkedList()
  obj.insert(1)
  obj.insert(2)
  obj.insert(3)
  obj.insert(4)
  obj.insert(5)
  obj.insert(6)
  obj.display()
  obj.middle_node()
  obj.insert(7)
  obj.display()
  obj.middle_node()

if __name__ == "__main__":
  main()

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6
 Tail to Head Nodes : 
  6  5  4  3  2  1
 Middle : 3

 Head to Tail Nodes : 
  1  2  3  4  5  6  7
 Tail to Head Nodes : 
  7  6  5  4  3  2  1
 Middle : 4
# Ruby Program
# Find middle element in doubly linked list

class Node 
	attr_reader :data, :next, :prev
	attr_accessor :data, :next, :prev
	def initialize(value) 
		self.data = value
		self.next = nil
		self.prev = nil
	end
end

class LinkedList 
	attr_reader :head, :tail
	attr_accessor :head, :tail
	def initialize() 
		@head = nil
		@tail = nil
	end
	def insert(value) 
		node = Node.new(value)
		if (node == nil) 
			print("Memory overflow\n")
			return
		end
		if (@head == nil) 
			@head = node
			@tail = node
		else 
			node.prev = @tail
			@tail.next = node
			@tail = node
		end
	end
	def display() 
		temp = @head
		if (temp == nil) 
			print("\nEmpty linked list\n")
			return
		end
		print("\n Head to Tail Nodes  :\n  ")
		while (temp != nil) 
			print(temp.data ,"  ")
			temp = temp.next
		end
		temp = @tail
		print("\n Tail to Head Nodes  :\n  ")
		while (temp != nil) 
			print(temp.data ,"  ")
			temp = temp.prev
		end
	end
	def middle_node() 
		if (@head != nil) 
			slow = @head
			fast = @head
			while (fast != nil and fast.next != nil and fast.next.next != nil) 
				slow = slow.next
				fast = fast.next.next
			end
			print("\n Middle  : ", slow.data ,"\n")
		else 
			print("Empty linked list")
		end
	end
end
def main() 
	obj = LinkedList.new()
	obj.insert(1)
	obj.insert(2)
	obj.insert(3)
	obj.insert(4)
	obj.insert(5)
	obj.insert(6)
	obj.display()
	obj.middle_node()
	obj.insert(7)
	obj.display()
	obj.middle_node()
end


main()

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6
 Tail to Head Nodes : 
  6  5  4  3  2  1
 Middle : 3

 Head to Tail Nodes : 
  1  2  3  4  5  6  7
 Tail to Head Nodes : 
  7  6  5  4  3  2  1
 Middle : 4
<?Php 
/*
 Php Program
 Find middle element in doubly linked list
*/

class Node {
  public $data;
  public $next;
  public $prev;

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

  function __construct() {
    $this->head = null;
    $this->tail = null;
  }
  public  function insert($value) {
    $node = new Node($value);
    if ($node == null) {
      echo("Memory overflow\n");
      return;
    }
    if ($this->head == null) {
      $this->head = $node;
      $this->tail = $node;
    } else {
      $node->prev = $this->tail;
      $this->tail->next = $node;
      $this->tail = $node;
    }
  }
  public  function display() {
    $temp = $this->head;
    if ($temp == null) {
      echo("\nEmpty linked list\n");
      return;
    }
    echo("\n Head to Tail Nodes : \n  ");
    while ($temp != null) {
      echo($temp->data ."  ");
      $temp = $temp->next;
    }
    $temp = $this->tail;
    echo("\n Tail to Head Nodes : \n  ");
    while ($temp != null) {
      echo($temp->data ."  ");
      $temp = $temp->prev;
    }
  }
  public  function middle_node() {
    if ($this->head != null) {
      $slow = $this->head;
      $fast = $this->head;
      while ($fast != null && $fast->next != null && $fast->next->next != null) {
        $slow = $slow->next;
        $fast = $fast->next->next;
      }
      echo("\n Middle : ". $slow->data ."\n");
    } else {
      echo("Empty linked list");
    }
  }
}

function main() {
  $obj = new LinkedList();
  $obj->insert(1);
  $obj->insert(2);
  $obj->insert(3);
  $obj->insert(4);
  $obj->insert(5);
  $obj->insert(6);
  $obj->display();
  $obj->middle_node();
  $obj->insert(7);
  $obj->display();
  $obj->middle_node();
}
main();

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6
 Tail to Head Nodes : 
  6  5  4  3  2  1
 Middle : 3

 Head to Tail Nodes : 
  1  2  3  4  5  6  7
 Tail to Head Nodes : 
  7  6  5  4  3  2  1
 Middle : 4
/*
 Node Js Program
 Find middle element in doubly linked list
*/

class Node {

	constructor(value) {
		this.data = value;
		this.next = null;
		this.prev = null;
	}
}
class LinkedList {
	
	constructor() {
		this.head = null;
		this.tail = null;
	}
	insert(value) {
		var node = new Node(value);
		if (node == null) {
			process.stdout.write("Memory overflow\n");
			return;
		}
		if (this.head == null) {
			this.head = node;
			this.tail = node;
		} else {
			node.prev = this.tail;
			this.tail.next = node;
			this.tail = node;
		}
	}
	display() {
		var temp = this.head;
		if (temp == null) {
			process.stdout.write("\nEmpty linked list\n");
			return;
		}
		process.stdout.write("\n Head to Tail Nodes : \n  ");
		while (temp != null) {
			process.stdout.write(temp.data + "  ");
			temp = temp.next;
		}
		temp = this.tail;
		process.stdout.write("\n Tail to Head Nodes : \n  ");
		while (temp != null) {
			process.stdout.write(temp.data + "  ");
			temp = temp.prev;
		}
	}
	middle_node() {
		if (this.head != null) {
			var slow = this.head;
			var fast = this.head;
			while (fast != null && fast.next != null && fast.next.next != null) {
				slow = slow.next;
				fast = fast.next.next;
			}
			process.stdout.write("\n Middle : " + slow.data + "\n");
		} else {
			process.stdout.write("Empty linked list");
		}
	}
}

function main() {
	var obj = new LinkedList();
	obj.insert(1);
	obj.insert(2);
	obj.insert(3);
	obj.insert(4);
	obj.insert(5);
	obj.insert(6);
	obj.display();
	obj.middle_node();
	obj.insert(7);
	obj.display();
	obj.middle_node();
}

main();

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6
 Tail to Head Nodes : 
  6  5  4  3  2  1
 Middle : 3

 Head to Tail Nodes : 
  1  2  3  4  5  6  7
 Tail to Head Nodes : 
  7  6  5  4  3  2  1
 Middle : 4
/*
 Swift 4 Program
 Find middle element in doubly linked list
*/

class Node {
  var data: Int;
  var next: Node? ;
  var prev: Node? ;
  init(_ value: Int) {
    self.data = value;
    self.next = nil;
    self.prev = nil;
  }
}
class LinkedList {
  var head: Node? ;
  var tail: Node? ;
  init() {
    self.head = nil;
    self.tail = nil;
  }
  func insert(_ value: Int) {
    let node: Node? = Node(value);
    if (node == nil) {
      print("Memory overflow\n");
      return;
    }
    if (self.head == nil) {
      self.head = node;
      self.tail = node;
    } else {
      node!.prev = self.tail;
      self.tail!.next = node;
      self.tail = node;
    }
  }
  func display() {
    var temp: Node? = self.head;
    if (temp == nil) {
      print("\nEmpty linked list\n");
      return;
    }
    print("\n Head to Tail Nodes :  ");
    while (temp != nil) {
      print(temp!.data ,terminator:"  ");
      temp = temp!.next;
    }
    temp = self.tail;
    print("\n Tail to Head Nodes : ");
    while (temp != nil) {
      print(temp!.data ,terminator:"  ");
      temp = temp!.prev;
    }
  }
  func middle_node() {
    if (self.head != nil) {
      var slow: Node? = self.head;
      var fast = self.head;
      while (fast != nil && fast!.next != nil && fast!.next!.next != nil) {
        slow = slow!.next;
        fast = fast!.next!.next;
      }
      print("\n Middle : ", slow!.data ,"\n");
    } else {
      print("Empty linked list");
    }
  }
}
func main() {
  let obj: LinkedList = LinkedList();
  obj.insert(1);
  obj.insert(2);
  obj.insert(3);
  obj.insert(4);
  obj.insert(5);
  obj.insert(6);
  obj.display();
  obj.middle_node();
  obj.insert(7);
  obj.display();
  obj.middle_node();
}
main();

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6
 Tail to Head Nodes : 
  6  5  4  3  2  1
 Middle : 3

 Head to Tail Nodes : 
  1  2  3  4  5  6  7
 Tail to Head Nodes : 
  7  6  5  4  3  2  1
 Middle : 4


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