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

• Last Updated : 27 Mar, 2023

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:

## C++

 `// C++ program to find n'th``// node in linked list``#include ``#include ``using` `namespace` `std;` `// Link list node``class` `Node``{``    ``public``:``    ``int` `data;``    ``Node* next;``};` `/* 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. */``void` `push(Node** head_ref,``          ``int` `new_data)``{``    ``// Allocate node``    ``Node* new_node = ``new` `Node();` `    ``// Put in the data``    ``new_node->data = new_data;` `    ``// Link the old list``    ``// of the new node``    ``new_node->next = (*head_ref);` `    ``// Move the head to point``    ``// to the new node``    ``(*head_ref) = new_node;``}` `// Takes head pointer of``// the linked list and index``// as arguments and return``// data at index``int` `GetNth(Node* head, ``int` `index)``{``    ``Node* current = head;` `    ``// The index of the``    ``// node we're currently``    ``// looking at``    ``int` `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``(0);``}` `// Driver Code``int` `main()``{``    ``// Start with the empty list``    ``Node* head = NULL;` `    ``// Use push() to construct list``    ``// 1->12->1->4->1``    ``push(&head, 1);``    ``push(&head, 4);``    ``push(&head, 1);``    ``push(&head, 12);``    ``push(&head, 1);` `    ``// Check the count function``    ``cout << ``"Element at index 3 is "` `<<``             ``GetNth(head, 3);``    ``return` `0;``}``// This code is contributed by rathbhupendra`

Output:

`Element at index 3 is 4`

Time Complexity: O(n)

Space complexity: O(1) using only constant variables

Method 2- With Recursion:
This method is contributed by MY_DOOM

Algorithm:

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

Implementation:

## C++

 `// C++ program to find n'th node in``// linked list using recursion``#include ``using` `namespace` `std;` `// Link list node``struct` `Node``{``    ``int` `data;``    ``struct` `Node* next;``};` `/*  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. */``void` `push(``struct` `Node** head_ref,``          ``int` `new_data)``{``    ``// Allocate node``    ``struct` `Node* new_node =``           ``(``struct` `Node*)``malloc``(``sizeof``(``struct` `Node));` `    ``// Put in the data``    ``new_node->data = new_data;` `    ``// Link the old list of the new node``    ``new_node->next = (*head_ref);` `    ``// Move the head to point to the new node``    ``(*head_ref) = new_node;``}` `/* Takes head pointer of the linked list and``   ``index as arguments and return data at index.``   ``(Don't use another variable)*/``int` `GetNth(``struct` `Node* head, ``int` `n)``{``    ``// If length of the list is less``    ``// than the given index, return -1``    ``if` `(head == NULL)``        ``return` `-1;` `    ``// If n equal to 0 return node->data``    ``if` `(n == 0)``        ``return` `head->data;` `    ``// Increase head to next pointer``    ``// n - 1: decrease the number of``    ``// recursions until n = 0``    ``return` `GetNth(head->next, n - 1);``}` `// Driver code``int` `main()``{``    ``// Start with the empty list``    ``struct` `Node* head = NULL;` `    ``// Use push() to construct list``    ``// 1->12->1->4->1``    ``push(&head, 1);``    ``push(&head, 4);``    ``push(&head, 1);``    ``push(&head, 12);``    ``push(&head, 1);` `    ``// Check the count function``    ``printf``(``"Element at index 3 is %d"``,``            ``GetNth(head, 3));``    ``getchar``();``}`

Output:

`Element at index 3 is 4`

Time Complexity: O(n)

Space Complexity: O(n) since using constant space to create nodes

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

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