Delete a Linked List node at a given position

• Difficulty Level : Easy
• Last Updated : 09 Jun, 2021

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->7Output: Linked List =  8->3->1->7Input: position = 0, Linked List = 8->2->3->1->7Output: Linked List = 2->3->1->

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++
• C
• Java
• Python
• C#
• Javascript

// 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 node

class 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 node

void printList( Node *node)

{

    while (node != NULL)

    {

        cout << node->data << " ";

        node = node->next;

    }

}

// Driver code

int 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 << "\nLinked List after Deletion at position 4: ";

    printList(head);

    return 0;

}

// This code is contributed by premsai2030

Output: 

Created Linked List: 8  2  3  1  7Linked List after Deletion at position 4: 8  2  3  1