Given a singly linked list and a position, delete a linked list node at the given position.
Example:
Input: position = 1, Linked List = 8->2->3->1->7 Output: Linked List = 8->3->1->7 Input: position = 0, Linked List = 8->2->3->1->7 Output: Linked List = 2->3->1->7
If the node to be deleted is the root, simply delete it. To delete a middle node, we must have a pointer to the node previous to the node to be deleted. So if positions are not zero, we run a loop position-1 times and get a pointer to the previous node.
Below is the implementation of the above idea.
C++
// A complete working C++ program to delete// a node in a linked list at a given position#include <iostream>using namespace std;// A linked list nodeclass Node{ public: int data; Node *next;};// Given a reference (pointer to pointer) to // the head of a list and an int inserts a // new node on the front of the list. void push(Node** head_ref, int new_data){ Node* new_node = new Node(); new_node->data = new_data; new_node->next = (*head_ref); (*head_ref) = new_node;}// Given a reference (pointer to pointer) to// the head of a list and a position, deletes// the node at the given position void deleteNode(Node **head_ref, int position){ // If linked list is empty if (*head_ref == NULL) return; // Store head node Node* temp = *head_ref; // If head needs to be removed if (position == 0) { // Change head *head_ref = temp->next; // Free old head free(temp); return; } // Find previous node of the node to be deleted for(int i = 0; temp != NULL && i < position - 1; i++) temp = temp->next; // If position is more than number of nodes if (temp == NULL || temp->next == NULL) return; // Node temp->next is the node to be deleted // Store pointer to the next of node to be deleted Node *next = temp->next->next; // Unlink the node from linked list free(temp->next); // Free memory // Unlink the deleted node from list temp->next = next; }// This function prints contents of linked // list starting from the given nodevoid printList( Node *node){ while (node != NULL) { cout << node->data << " "; node = node->next; }}// Driver codeint main(){ // Start with the empty list Node* head = NULL; push(&head, 7); push(&head, 1); push(&head, 3); push(&head, 2); push(&head, 8); cout << "Created Linked List: "; printList(head); deleteNode(&head, 4); cout << "Linked List after Deletion at position 4: "; printList(head); return 0;}// This code is contributed by premsai2030 |
Output:
Created Linked List: 8 2 3 1 7 Linked List after Deletion at position 4: 8 2 3 1
Time Complexity: O(n), where n represents the length of the given linked list.
Auxiliary Space: O(1), no extra space is required, so it is a constant.
Please refer complete article on Delete a Linked List node at a given position for more details!
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