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

• Last Updated : 22 Jun, 2022

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 ` `#include `   `// 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` `    ``// off 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(``struct` `Node* head, ` `           ``int` `index)` `{` `    ``struct` `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` `    ``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(1)  since using constant space for nodes and variables.

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

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