Given a doubly linked list and a position **n**. The task is to delete the node at the given position **n** from the beginning.

Initial doubly linked list

Doubly Linked List after deletion of node at position **n** = 2

**Approach:** Following are the steps:

- Get the pointer to the node at position
**n**by traversing the doubly linked list up to the**nth**node from the beginning. - Delete the node using the pointer obtained in Step 1. Refer this post.

/* C++ implementation to delete a doubly Linked List node at the given position */ #include <bits/stdc++.h> using namespace std; /* 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); } /* Function to delete the node at the given position in the doubly linked list */ void deleteNodeAtGivenPos(struct Node** head_ref, int n) { /* if list in NULL or invalid position is given */ if (*head_ref == NULL || n <= 0) return; struct Node* current = *head_ref; int i; /* traverse up to the node at position 'n' from the beginning */ for (int i = 1; current != NULL && i < n; i++) current = current->next; /* if 'n' is greater than the number of nodes in the doubly linked list */ if (current == NULL) return; /* delete the node pointed to by 'current' */ deleteNode(head_ref, current); } /* 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 beginning, 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 */ void printList(struct Node* head) { while (head != NULL) { cout << head->data << " "; head = head->next; } } /* Driver program to test above functions*/ int main() { /* Start with the empty list */ struct Node* head = NULL; /* Create the doubly linked list 10<->8<->4<->2<->5 */ push(&head, 5); push(&head, 2); push(&head, 4); push(&head, 8); push(&head, 10); cout << "Doubly linked list before deletion:n"; printList(head); int n = 2; /* delete node at the given position 'n' */ deleteNodeAtGivenPos(&head, n); cout << "\nDoubly linked list after deletion:n"; printList(head); return 0; }

Output:

Doubly linked list before deletion: 10 8 4 2 5 Doubly linked list after deletion: 10 4 2 5

Time Complexity: O(n), in worst case where n is the number of nodes in the doubly linked list.

This article is contributed by **Ayush Jauhari**. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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