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# Javascript Program For Writing A Function To Get Nth Node In A Linked List

Write a GetNth() function that takes a linked list and an integer index and returns the data value stored in the node at that index position.

Example:

```Input:  1->10->30->14,  index = 2
Output: 30
The node at index 2 is 30```

Algorithm:

```1. Initialize count = 0
2. Loop through the link list
a. If count is equal to the passed index then return
current node
b. Increment count
c. change current to point to next of the current.```

Implementation:

## Javascript

 `// Javascript program to find n'th ` `// node in linked list`   `class Node ` `{` `    ``constructor(d) ` `    ``{` `        ``this``.data = d;` `        ``this``.next = ``null``;` `    ``}` `}`   `// Head of list` `var` `head; `   `/* Takes index as argument and ` `   ``return data at index */` `function` `GetNth(index) ` `{` `    ``var` `current = head;`   `    ``// Index of Node we are currently ` `    ``// looking at` `    ``var` `count = 0; ` `    `  `    ``while` `(current != ``null``) ` `    ``{` `        ``if` `(count == index)` `           ``return` `current.data;` `        ``count++;` `        ``current = current.next;` `    ``}`   `    ``/* if we get to this line, the caller ` `       ``was asking for a non-existent element ` `       ``so we assert fail */` `    ``assert (``false``);` `    ``return` `0;` `}`   `/* Given a reference to the head of a ` `   ``list and an int, inserts a new Node ` `   ``on the front of the list. */` `function` `push(new_data) ` `{` `    ``// 1. Alloc the Node and put data ` `    ``var` `new_Node = ``new` `Node(new_data);`   `    ``// 2. Make next of new Node as head` `    ``new_Node.next = head;`   `    ``// 3. Move the head to point to new Node` `    ``head = new_Node;` `}`   `// Driver code` `    `  `// Start with empty list ` `// Use push() to construct list ` `// 1->12->1->4->1` `push(1);` `push(4);` `push(1);` `push(12);` `push(1);`   `// Check the count function ` `console.log(``"Element at index 3 is "` `+ ` `                ``GetNth(3));` `// This code is contributed by todaysgaurav`

Output:

`Element at index 3 is 4`

Time Complexity: O(n)

Space Complexity: O(1) since using constant space to create nodes and variables.

Method 2- With Recursion:

Algorithm:

```getnth(node,n)
1. Initialize count = 0
2. if count==n
return node->data
3. else
return getnth(node->next, n-1)```

Implementation:

## Javascript

 `// javascript program to find n'th node ` `// in linked list using recursion    `   `// Linked List node` `class Node` `{` `    ``constructor(val) ` `    ``{` `        ``this``.data = val;` `        ``this``.next = ``null``;` `    ``}` `}`   `/* Given a reference (pointer to pointer) to the` `   ``head of a list and an int, push a new node on` `   ``the front of the list. */` `function` `push(head, new_data) ` `{` `    ``// Allocate node` `    ``var` `new_node = ``new` `Node(new_data);`   `    ``// Put in the data ` `    ``new_node.data = new_data;` `    `  `    ``new_node.next = head;` `    ``head = new_node;` `    ``return` `head;` `}`   `/* Takes head pointer of the linked list and ` `   ``index as arguments and return data at index */` `function` `GetNth(head, n) ` `{` `    ``var` `count = 0;` `        `  `    ``// Edge case - if head is null` `    ``if` `(head == ``null``) ` `        ``return` `-1;` `        `  `    ``// if count equal too n return node.data` `    ``if` `(count == n)` `        ``return` `head.data;`   `    ``// Recursively decrease n and increase` `    ``// head to next pointer` `    ``return` `GetNth(head.next, n - 1);` `}`   `// Driver code` `    `  `// Start with the empty list ` `var` `head = ``null``;`   `// Use push() to construct list` `// 1->12->1->4->1` `head = push(head, 1);` `head = push(head, 4);` `head = push(head, 1);` `head = push(head, 12);` `head = push(head, 1);`   `// Check the count function ` `console.log(``"Element at index 3 is "``, ` `                ``GetNth(head, 3));` `// This code contributed by gauravrajput1`

Output:

`Element at index 3 is 4`

Time Complexity: O(n)

Space Complexity: O(n) for call stack because using recursion

Please refer complete article on Write a function to get Nth node in a Linked List for more details!

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