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Delete a Doubly Linked List node at a given position in C++
In this tutorial, we are going to learn how to delete a node in doubly linked list with the given position.
Let's see the steps to solve the problem.
Write struct with data, prev and next pointers.
Write a function to insert the node into the doubly linked list.
Initialize the doubly linked list with dummy data.
Initialize the position to delete the node.
Iterate over the linked list and find the node with the given position to delete the node.
Write a function to delete the node. Consider the following three cases while deleting the node.
If the node is head node, then move the head to next node.
If the node is middle node, then link the next node to the previous node
If the node is end node, then remove the previous node link.
Example
Let's see the code.
#include <bits/stdc++.h>
using namespace std;
struct Node {
int data;
struct Node *prev, *next;
};
void deleteNode(struct Node** head_ref, struct Node* del) {
if (*head_ref == NULL || del == NULL) {
return;
}
// head node
if (*head_ref == del) {
*head_ref = del->next;
}
// middle node
if (del->next != NULL) {
del->next->prev = del->prev;
}
// end node
if (del->prev != NULL) {
del->prev->next = del->next;
}
free(del);
}
void deleteNodeAtGivenPosition(struct Node** head_ref, int n) {
if (*head_ref == NULL || n <= 0) {
return;
}
struct Node* current = *head_ref;
int i;
for (int i = 1; current != NULL && i < n; i++) {
current = current->next;
}
if (current == NULL) {
return;
}
deleteNode(head_ref, current);
}
void insertNode(struct Node** head_ref, int new_data) {
struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
new_node->data = new_data;
new_node->prev = NULL;
new_node->next = (*head_ref);
if ((*head_ref) != NULL) {
(*head_ref)->prev = new_node;
}
(*head_ref) = new_node;
}
void printLinkedList(struct Node* head) {
while (head != NULL) {
cout << head->data << "->";
head = head->next;
}
}
int main() {
struct Node* head = NULL;
insertNode(&head, 5);
insertNode(&head, 2);
insertNode(&head, 4);
insertNode(&head, 8);
insertNode(&head, 10);
cout << "Doubly linked list before deletion" << endl;
printLinkedList(head);
int n = 2;
deleteNodeAtGivenPosition(&head, n);
cout << "\nDoubly linked list after deletion" << endl;
printLinkedList(head);
return 0;
}Output
If you execute the above program, then you will get the following result.
Doubly linked list before deletion 10->8->4->2->5-> Doubly linked list after deletion 10->4->2->5->
Conclusion
If you have any queries in the tutorial, mention them in the comment section.
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