Delete initial n nodes in a doubly linked list

Remove initial n nodes in a doubly linked list

Here given code implementation process.

//C Program
//Delete initial N nodes 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 rear
    while (temp != NULL) {
      //print Node value
      printf("%3d", temp->data);
      temp = temp->prev;
    }
  }

}
void delete_front_n(int n)
{
  if(head==NULL)
  {
    return;
  }
    
  struct Node*temp=head;
  int counter = 0;
  //Check given deleted node are exist or not
  while(temp!=NULL && counter < n)
  {
    counter++;
    temp=temp->next;
  }

  if(counter >= n)
  {
    counter = n;
    while(counter > 0 && head!=NULL)
    {
      temp=head;
      
      head=head->next;

      if(head!=NULL)
      {
        head->prev=NULL;
      }
      if(temp==tail)
      {
        //when delete all nodes
        tail=NULL;
      }
      free(temp);
      temp=NULL;
      counter--;
    }
  }
  else
  {
    printf("\n%d Nodes are not exist in linked list\n",n );
  }
  

}


int main() {

  //Insert element of linked list
  insert(1);
  insert(2);
  insert(3);
  insert(4);
  insert(5);
  insert(6);
  insert(7);
  insert(8);
 
  //display all node
  display();
  int n = 5;
  printf("\n\n After Delete Starting %d Nodes\n",n);
  delete_front_n(n);

  display();
  return 0;
}

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6  7  8
 Tail to Head Nodes : 
  8  7  6  5  4  3  2  1

 After Delete Starting 5 Nodes

 Head to Tail Nodes : 
  6  7  8
 Tail to Head Nodes : 
  8  7  6
/*
 C++ Program
 Delete initial N nodes 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 delete_front_n(int n) {
    if (this->head == NULL) {
      return;
    }
    Node *temp = this->head;
    int counter = 0;
    while (temp != NULL && counter < n) {
      counter++;
      temp = temp->next;
    }
    if (counter >= n) {
      counter = n;
      while (counter > 0 && this->head != NULL) {
        temp = this->head;
        this->head = this->head->next;
        if (this->head != NULL) {
          this->head->prev = NULL;
        }
        if (temp == this->tail) {
          this->tail = NULL;
        }
        temp = NULL;
        counter--;
      }
    } else {
      cout << "\n" << n << " Nodes are not exist in linked list\n";
    }
  }
};

int main() {
  LinkedList obj ;
  obj.insert(1);
  obj.insert(2);
  obj.insert(3);
  obj.insert(4);
  obj.insert(5);
  obj.insert(6);
  obj.insert(7);
  obj.insert(8);
  cout << "\nBefore Delete";
  obj.display();
  int n = 5;
  obj.delete_front_n(n);
  cout << "\n\n After Delete initial " << n << " Nodes\n";
  obj.display();
  return 0;
}

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6  7  8
 Tail to Head Nodes : 
  8  7  6  5  4  3  2  1

 After Delete Starting 5 Nodes

 Head to Tail Nodes : 
  6  7  8
 Tail to Head Nodes : 
  8  7  6
/*
  Java Program
  Delete initial N nodes 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;
    }

  }
  public void delete_front_n(int n) {

    if (head == null) {
      return;
    }
    Node temp = head;
    int counter = 0;

    while (temp != null && counter < n) {
      counter++;
      temp = temp.next;
    }

    if (counter >= n) {
      counter = n;

      while (counter > 0 && head != null) {
        temp = head;
        head = head.next;

        if (head != null) {
          head.prev = null;
        }

        if (temp == tail) {
          //Delete last node
          tail = null;
        }
      
        temp = null;
        counter--;
      }
    } else {

      System.out.print("\n"+n+" Nodes are not exist in linked list\n");
    }
  }



  public static void main(String[] args) {
    LinkedList obj = new LinkedList();
    obj.insert(1);
    obj.insert(2);
    obj.insert(3);
    obj.insert(4);
    obj.insert(5);
    obj.insert(6);
    obj.insert(7);
    obj.insert(8);
  
    System.out.print("\nBefore Delete");
    obj.display();

    int n = 5;
    obj.delete_front_n(n);

    System.out.print("\n\n After Delete initial "+n+" Nodes\n");
    obj.display();
  }


}

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6  7  8
 Tail to Head Nodes : 
  8  7  6  5  4  3  2  1

 After Delete Starting 5 Nodes

 Head to Tail Nodes : 
  6  7  8
 Tail to Head Nodes : 
  8  7  6
/*
  C# Program
  Delete initial N nodes 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;
		}

	}
	public void delete_front_n(int n) {

		if (head == null) {
			return;
		}
		Node temp = head;
		int counter = 0;

		while (temp != null && counter < n) {
			counter++;
			temp = temp.next;
		}

		if (counter >= n) {
			counter = n;

			while (counter > 0 && head != null) {
				temp = head;
				head = head.next;

				if (head != null) {
					head.prev = null;
				}

				if (temp == tail) {
					//Delete last node
					tail = null;
				}

				temp = null;
				counter--;
			}
		} else {

			Console.Write("\n"+n+" Nodes are not exist in linked list\n");
		}
	}



	public static void Main(String[] args) {
		LinkedList obj = new LinkedList();
		obj.insert(1);
		obj.insert(2);
		obj.insert(3);
		obj.insert(4);
		obj.insert(5);
		obj.insert(6);
		obj.insert(7);
		obj.insert(8);

		Console.Write("\nBefore Delete");
		obj.display();

		int n = 5;
		obj.delete_front_n(n);

		Console.Write("\n\n After Delete initial "+n+" Nodes\n");
		obj.display();
	}


}

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6  7  8
 Tail to Head Nodes : 
  8  7  6  5  4  3  2  1

 After Delete Starting 5 Nodes

 Head to Tail Nodes : 
  6  7  8
 Tail to Head Nodes : 
  8  7  6
# Python 3 Program
# Delete initial N nodes 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 delete_front_n(self, n) :
    if (self.head == None) :
      return
    
    temp = self.head
    counter = 0
    while (temp != None and counter < n) :
      counter += 1
      temp = temp.next
    
    if (counter >= n) :
      counter = n
      while (counter > 0 and self.head != None) :
        temp = self.head
        self.head = self.head.next
        if (self.head != None) :
          self.head.prev = None
        
        if (temp == self.tail) :
          self.tail = None
        
        temp = None
        counter -= 1
      
    else :
      print("\n", n ," Nodes are not exist in 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.insert(7)
  obj.insert(8)
  print("\nBefore Delete")
  obj.display()
  n = 5
  obj.delete_front_n(n)
  print("\n\n After Delete initial ", n ," Nodes")
  obj.display()
  

if __name__ == "__main__":
  main()

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6  7  8
 Tail to Head Nodes : 
  8  7  6  5  4  3  2  1

 After Delete Starting 5 Nodes

 Head to Tail Nodes : 
  6  7  8
 Tail to Head Nodes : 
  8  7  6
# Ruby Program
# Delete initial N nodes 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 delete_front_n(n) 
		if (@head == nil) 
			return
		end
		temp = @head
		counter = 0
		while (temp != nil and counter < n) 
			counter += 1
			temp = temp.next
		end
		if (counter >= n) 
			counter = n
			while (counter > 0 and @head != nil) 
				temp = @head
				@head = @head.next
				if (@head != nil) 
					@head.prev = nil
				end
				if (temp == @tail) 
					@tail = nil
				end
				temp = nil
				counter -= 1
			end
		else 
			print("\n", n ," Nodes are not exist in linked list\n")
		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.insert(7)
	obj.insert(8)
	print("\nBefore Delete")
	obj.display()
	n = 5
	obj.delete_front_n(n)
	print("\n\n After Delete initial ", n ," Nodes")
	obj.display()
end
main()

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6  7  8
 Tail to Head Nodes : 
  8  7  6  5  4  3  2  1

 After Delete Starting 5 Nodes

 Head to Tail Nodes : 
  6  7  8
 Tail to Head Nodes : 
  8  7  6
<?php
/*
 Php Program
 Delete initial N nodes 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 = $temp->prev;
    }
  }
  public  function delete_front_n($n) {
    if ($this->head == null) {
      return;
    }
    $temp = $this->head;
    $counter = 0;
    while ($temp != null && $counter < $n) {
      $counter++;
      $temp = $temp->next;
    }
    if ($counter >= $n) {
      $counter = $n;
      while ($counter > 0 && $this->head != null) {
        $temp = $this->head;
        $this->head = $this->head->next;
        if ($this->head != null) {
          $this->head->prev = null;
        }
        if ($temp == $this->tail) {
          $this->tail = null;
        }
        $temp = null;
        $counter--;
      }
    } else {
      echo("\n". $n ." Nodes are not exist in linked list\n");
    }
  }
}

function main() {
  $obj = new LinkedList();
  $obj->insert(1);
  $obj->insert(2);
  $obj->insert(3);
  $obj->insert(4);
  $obj->insert(5);
  $obj->insert(6);
  $obj->insert(7);
  $obj->insert(8);
  echo("\nBefore Delete");
  $obj->display();
  $n = 5;
  $obj->delete_front_n($n);
  echo("\n\n After Delete initial ". $n ." Nodes\n");
  $obj->display();
}
main();

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6  7  8
 Tail to Head Nodes : 
  8  7  6  5  4  3  2  1

 After Delete Starting 5 Nodes

 Head to Tail Nodes : 
  6  7  8
 Tail to Head Nodes : 
  8  7  6
/*
 Node Js Program
 Delete initial N nodes 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;
		}
	}
	delete_front_n(n) {
		if (this.head == null) {
			return;
		}
		var temp = this.head;
		var counter = 0;
		while (temp != null && counter < n) {
			counter++;
			temp = temp.next;
		}
		if (counter >= n) {
			counter = n;
			while (counter > 0 && this.head != null) {
				temp = this.head;
				this.head = this.head.next;
				if (this.head != null) {
					this.head.prev = null;
				}
				if (temp == this.tail) {
					this.tail = null;
				}
				temp = null;
				counter--;
			}
		} else {
			process.stdout.write("\n" + n + " Nodes are not exist in linked list\n");
		}
	}
}

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.insert(7);
	obj.insert(8);
	process.stdout.write("\nBefore Delete");
	obj.display();
	var n = 5;
	obj.delete_front_n(n);
	process.stdout.write("\n\n After Delete initial " + n + " Nodes\n");
	obj.display();
}


main();

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6  7  8
 Tail to Head Nodes : 
  8  7  6  5  4  3  2  1

 After Delete Starting 5 Nodes

 Head to Tail Nodes : 
  6  7  8
 Tail to Head Nodes : 
  8  7  6
/*
 Swift 4 Program
 Delete initial N nodes 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");
      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 delete_front_n(_ n: Int) {
    if (self.head == nil) {
      return;
    }
    var temp: Node? = self.head;
    var counter: Int = 0;
    while (temp != nil && counter < n) {
      counter += 1;
      temp = temp!.next;
    }
    if (counter >= n) {
      counter = n;
      while (counter > 0 && self.head != nil) {
        temp = self.head;
        self.head = self.head!.next;
        if (self.head != nil) {
          self.head!.prev = nil;
        }
        if (temp === self.tail) {
          self.tail = nil;
        }
        temp = nil;
        counter -= 1;
      }
    } else {
      print("\n", n ," Nodes are not exist in 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.insert(7);
  obj.insert(8);
  print("\nBefore Delete");
  obj.display();
  let n: Int = 5;
  obj.delete_front_n(n);
  print("\n\n After Delete initial ", n ," Nodes");
  obj.display();
}
main();

Output

 Head to Tail Nodes : 
  1  2  3  4  5  6  7  8
 Tail to Head Nodes : 
  8  7  6  5  4  3  2  1

 After Delete Starting 5 Nodes

 Head to Tail Nodes : 
  6  7  8
 Tail to Head Nodes : 
  8  7  6

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