Implement in C++ a doubly linked list using two dummy nodes (one for the head an
ID: 3783363 • Letter: I
Question
Implement in C++ a doubly linked list using two dummy nodes (one for the head and one for the tail). The code must contain a ListNode, List, and Listltr class
The code for the copy constructor and the operator()= method are shown below
List::List(const List& source) t Copy Constructor head new ListNode; tail new ListNode; head next tail; tail previous head; count 0; List It r iter (source head->next) while (liter isPastEnd deep copy of the list insert AtTail(iter.retrieve iter.moveForward List& List operator (const List& source) //Equals operator if this &source;) return this; else t make Empty Listitr iter (source. head- next); while (liter. is PastEnd insertAtTail(iter. retrieve iter. moveForward return this;Explanation / Answer
#include <stdio.h>
#include <stdlib.h>
/* a node of the doubly linked list */
struct node
{
int data;
struct node *next;
struct node *prev;
};
/* Function to delete a node in a Doubly Linked List.
head_ref --> pointer to head node pointer.
del --> pointer to node to be deleted. */
void deleteNode(struct node **head_ref, struct node *del)
{
/* base case */
if(*head_ref == NULL || del == NULL)
return;
/* If node to be deleted is head node */
if(*head_ref == del)
*head_ref = del->next;
/* Change next only if node to be deleted is NOT the last node */
if(del->next != NULL)
del->next->prev = del->prev;
/* Change prev only if node to be deleted is NOT the first node */
if(del->prev != NULL)
del->prev->next = del->next;
/* Finally, free the memory occupied by del*/
free(del);
return;
}
/* UTILITY FUNCTIONS */
/* Function to insert a node at the beginning of the Doubly Linked List */
void push(struct node** head_ref, int new_data)
{
/* allocate node */
struct node* new_node =
(struct node*) malloc(sizeof(struct node));
/* put in the data */
new_node->data = new_data;
/* since we are adding at the begining,
prev is always NULL */
new_node->prev = NULL;
/* link the old list off the new node */
new_node->next = (*head_ref);
/* change prev of head node to new node */
if((*head_ref) != NULL)
(*head_ref)->prev = new_node ;
/* move the head to point to the new node */
(*head_ref) = new_node;
}
/* Function to print nodes in a given doubly linked list
This function is same as printList() of singly linked lsit */
void printList(struct node *node)
{
while(node!=NULL)
{
printf("%d ", node->data);
node = node->next;
}
}
/* Drier program to test above functions*/
int main()
{
/* Start with the empty list */
struct node* head = NULL;
/* Let us create the doubly linked list 10<->8<->4<->2 */
push(&head, 2);
push(&head, 4);
push(&head, 8);
push(&head, 10);
printf(" Original Linked list ");
printList(head);
/* delete nodes from the doubly linked list */
deleteNode(&head, head); /*delete first node*/
deleteNode(&head, head->next); /*delete middle node*/
deleteNode(&head, head->next); /*delete last node*/
/* Modified linked list will be NULL<-8->NULL */
printf(" Modified Linked list ");
printList(head);
getchar();
}
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