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# Java 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:

## Java

 `// Java program to find n'th node ` `// in linked list` `class` `Node` `{` `    ``int` `data;` `    ``Node next;` `    ``Node(``int` `d)` `    ``{` `        ``data = d;` `        ``next = ``null``;` `    ``}` `}`   `class` `LinkedList ` `{` `    ``// Head of list` `    ``Node head; `   `    ``// Takes index as argument and ` `    ``// return data at index` `    ``public` `int` `GetNth(``int` `index)` `    ``{` `        ``Node current = head;`   `        ``// Index of Node we are` `        ``// 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` `(``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. */` `    ``public` `void` `push(``int` `new_data)` `    ``{` `        ``// 1. Alloc the Node and put data` `        ``Node 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` `    ``public` `static` `void` `main(String[] args)` `    ``{` `        ``// Start with empty list` `        ``LinkedList llist = ``new` `LinkedList();`   `        ``// Use push() to construct list` `        ``// 1->12->1->4->1 ` `        ``llist.push(``1``);` `        ``llist.push(``4``);` `        ``llist.push(``1``);` `        ``llist.push(``12``);` `        ``llist.push(``1``);`   `        ``// Check the count function ` `        ``System.out.println(``"Element at index 3 is "` `+ ` `                            ``llist.GetNth(``3``));` `    ``}` `}`

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:

## Java

 `// Java program to find n'th node ` `// in linked list using recursion` `class` `GFG ` `{` `    ``// Link list node ` `    ``static` `class` `Node ` `    ``{` `        ``int` `data;` `        ``Node next;` `        ``Node(``int` `data) ` `        ``{ ` `           ``this``.data = data; ` `        ``}` `    ``}`   `    ``/* 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. */` `    ``static` `Node push(Node head, ``int` `new_data)` `    ``{` `        ``// Allocate node ` `        ``Node 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*/` `    ``static` `int` `GetNth(Node head, ``int` `n)` `    ``{` `        ``int` `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` `    ``public` `static` `void` `main(String args[])` `    ``{` `        ``// Start with the empty list` `        ``Node 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 ` `        ``System.out.printf(``"Element at index 3 is %d"``,` `                           ``GetNth(head, ``3``));` `    ``}` `}` `// This code is contributed by Arnab Kundu`

Output:

`Element at index 3 is 4`

Time Complexity: O(n)

Space complexity: O(n) for call stack

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

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