Deletion of node at beginning(front) in DLL

To delete any node from front location of Doubly Linked List(DLL),we have to follow below steps :

• Take one Temp Variable and assign it by HeadPointer.
• Then we have to apply node arrangement and after node arrangement, delete the Temp variable.
• Refer the below Working Process :

Working Process

Code Implementation

#include <stdio.h>
#include<iostream>
#include<conio.h>
#include<math.h>
#include<stdlib.h>
#include<malloc.h>
struct CreateNode   // Node Structure Initialization
{
	int  data;          // for data element
	struct CreateNode* nextNode;   //for storing the address of next element
	struct CreateNode* prevNode;  // for storing the address of previuos element
};
struct CreateNode *HeadPointer = NULL;    // Initialization of HeadPointer

void DeletetNodeAtFrontDLL()   // Method of Front Deletion
{
	struct CreateNode* Temp = HeadPointer;
    
	Temp->nextNode->prevNode = NULL;
	HeadPointer = Temp->nextNode;
	std::cout << "\nDataElement " << Temp->data << " has been deleted at front\n";

}
int main()
{
	int choice=0;
	//Create 5 node statically and Initialize manually
	struct CreateNode* Node1 = (struct CreateNode *)malloc(sizeof(struct CreateNode *));
	struct CreateNode* Node2 = (struct CreateNode *)malloc(sizeof(struct CreateNode *));
	struct CreateNode* Node3 = (struct CreateNode *)malloc(sizeof(struct CreateNode *));
	struct CreateNode* Node4 = (struct CreateNode *)malloc(sizeof(struct CreateNode *));
	struct CreateNode* Node5 = (struct CreateNode *)malloc(sizeof(struct CreateNode *));
	//Data Initialization
	Node1->data = 90;
	Node2->data = 100;
	Node3->data = 200;
	Node4->data = 300;
	Node5->data = 400;
	//Address Initialization
	Node1->prevNode = NULL;
	Node1->nextNode = Node2;

	Node2->prevNode = Node1;
	Node2->nextNode = Node3;

	Node3->prevNode = Node2;
	Node3->nextNode = Node4;

	Node4->prevNode = Node3;
	Node4->nextNode = Node5;

	Node5->prevNode = Node4;
	Node5->nextNode = NULL;

	HeadPointer = Node1;  // HeadPointer pointing to the Node1

	printf("Node Before Deletion : ");
	struct CreateNode* Temp = HeadPointer;
	while (Temp->nextNode != NULL)
	{
		printf("%d ", Temp->data);
		Temp = Temp->nextNode;
	}
	printf("%d ", Temp->data);
	while (choice == 0)
	{
		printf("\nPress 0 for front deletion :");
		std::cin >> choice;
		if (choice == 0)
		{
			DeletetNodeAtFrontDLL();
		}
		else
		{
			choice = 1; // dont delete the front node
		}
	}


	printf("\nNode data after Deletion process :\n");
	Temp = HeadPointer;
	while (Temp->nextNode != NULL)
	{
		printf("%d ", Temp->data);
		Temp = Temp->nextNode;
	}
	printf("%d ", Temp->data);
	_getch();
	return 0;
}

Time & Space Complexity

• Time Complexity will be O(1).
• Space Complexity will be O(1).