Javascript Program For Inserting A Node After The N-th Node From The End

// JavaScript implementation to
// insert a node after 
// the n-th node from the end 

// structure of a node
class Node {
    constructor() {
        this.data = 0;
        this.next = null;
    }
}

// function to get a new node
function getNode(data) {
    // allocate memory for the node
    let newNode = new Node();

    // put in the data
    newNode.data = data;
    newNode.next = null;
    return newNode;
}

// function to insert a node after the
// nth node from the end
function insertAfterNthNode(head, n, x) {
    // if list is empty
    if (head == null)
        return;

    // get a new node for the value 'x'
    let newNode = getNode(x);
    let ptr = head;
    let len = 0, i;

    // find length of the list, i.e, the
    // number of nodes in the list
    while (ptr != null) {
        len++;
        ptr = ptr.next;
    }

    // traverse up to the nth node from the end
    ptr = head;
    for (i = 1; i <= (len - n); i++)
        ptr = ptr.next;

    // insert the 'newNode' by making the
    // necessary adjustment in the links
    newNode.next = ptr.next;
    ptr.next = newNode;
}

// function to print the list
function printList(head) {
    while (head != null) {
        console.log(head.data + " ");
        head = head.next;
    }
}

// Driver code

// Creating list 1->3->4->5
let head = getNode(1);
head.next = getNode(3);
head.next.next = getNode(4);
head.next.next.next = getNode(5);

let n = 4, x = 2;

console.log("Original Linked List: ");
printList(head);

insertAfterNthNode(head, n, x);
console.log("Linked List After Insertion: ");
printList(head);

// This code contributed by gauravrajput1

// JavaScript implementation to
// insert a node after the
// nth node from the end
// structure of a node
class Node {
    constructor() {
        this.data = 0;
        this.next = null;
    }
}

// function to get a new node
function getNode(data) {
    // allocate memory for the node
    let newNode = new Node();

    // put in the data
    newNode.data = data;
    newNode.next = null;
    return newNode;
}

// function to insert a node after
// the nth node from the end
function insertAfterNthNode(head, n, x) {
    // if list is empty
    if (head == null) return;

    // get a new node for the value 'x'
    let newNode = getNode(x);

    // Initializing the slow
    // and fast pointers
    let slow_ptr = head;
    let fast_ptr = head;

    // move 'fast_ptr' to point to the
    // nth node from the beginning
    for (let i = 1; i <= n - 1; i++)
        fast_ptr = fast_ptr.next;

    // iterate until 'fast_ptr' points
    // to the last node
    while (fast_ptr.next != null) {
        // move both the pointers to the
        // respective next nodes
        slow_ptr = slow_ptr.next;
        fast_ptr = fast_ptr.next;
    }

    // insert the 'newNode' by making the
    // necessary adjustment in the links
    newNode.next = slow_ptr.next;
    slow_ptr.next = newNode;
}

// function to print the list
function printList(head) {
    while (head != null) {
        console.log(head.data);
        head = head.next;
    }
}

// Driver code
// Creating list 1->3->4->5
let head = getNode(1);
head.next = getNode(3);
head.next.next = getNode(4);
head.next.next.next = getNode(5);

let n = 4,
    x = 2;
console.log("Original Linked List: ");
printList(head);

insertAfterNthNode(head, n, x);
console.log("Linked List After Insertion:");
printList(head);