HackerRank Insert a Node at a Specific Position in a Linked List | JS Solution

Problem

HackerRank detailed problem description can be found here.

We need to create a function insertNodeAtPosition(head, data, position) {}. This function should:

• Create a new node using provided data
• Insert that newly created node at the provided position inside a Singly Linked List
• Lastly, return the head node

Inputs & Outputs

/*
param {Node} head
param {number} data
param {number} position
return {Node}
*/

Test Case

I am using data of a string data type in the example below in order to make this algorithm just a bit more visual, though in the actual coded solution the data of a number data type will be used.

Imagine this is our initial linked list with 3 nodes in it. We are asked to create a new node with data bacon and insert it in the position: 2

This is how our linked list would look like after we are done with our function:

Data Structures

Singly linked list, number

Code

function insertNodeAtPosition(head, data, position) {
  let count = 0;
  let prev = null;
  let current = head;
  let newNode = new SinglyLinkedListNode(data);

  while (count < position && current) {
    prev = current;
    current = current.next;
    count++;
  }

  if (prev) {
    prev.next = newNode;
    newNode.next = current;
  }

  return head;
}

* The code above doesn't consider the cases where we are given an empty linked list or position: 0.

Sources

Insert a node at a specific position in a linked list algorithm by HackerRank