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# Find the middle of a given linked list

• Difficulty Level : Easy
• Last Updated : 12 Oct, 2021

Given a singly linked list, find the middle of the linked list. For example, if the given linked list is 1->2->3->4->5 then the output should be 3.
If there are even nodes, then there would be two middle nodes, we need to print the second middle element. For example, if given linked list is 1->2->3->4->5->6 then the output should be 4.

Method 1:
Traverse the whole linked list and count the no. of nodes. Now traverse the list again till count/2 and return the node at count/2.

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Method 2:
Traverse linked list using two pointers. Move one pointer by one and the other pointers by two. When the fast pointer reaches the end slow pointer will reach the middle of the linked list.

Below image shows how printMiddle function works in the code : ## C++

 `// C++ program for the above approach`   `#include ` `using` `namespace` `std;`   `class` `Node{` `    ``public``:` `        ``int` `data;` `        ``Node *next;` `};`   `class` `NodeOperation{` `  ``public``: ` `  `  `    ``// Function to add a new node` `    ``void` `pushNode(``class` `Node** head_ref,``int` `data_val){` `      `  `        ``// Allocate node ` `        ``class` `Node *new_node = ``new` `Node();` `        `  `         ``// Put in the data ` `        ``new_node->data = data_val;` `        `  `        ``// 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;` `    ``}` `    `  `    ``// A utility function to print a given linked list` `    ``void` `printNode(``class` `Node *head){` `        ``while``(head != NULL){` `            ``cout <data << ``"->"``;` `            ``head = head->next;` `        ``}` `        ``cout << ``"NULL"` `<< endl;` `    ``}` `    `  `    ``void` `printMiddle(``class` `Node *head){` `        ``struct` `Node *slow_ptr = head;` `        ``struct` `Node *fast_ptr = head;` ` `  `        ``if` `(head!=NULL)` `        ``{` `            ``while` `(fast_ptr != NULL && fast_ptr->next != NULL)` `            ``{` `                ``fast_ptr = fast_ptr->next->next;` `                ``slow_ptr = slow_ptr->next;` `            ``}` `            ``cout << ``"The middle element is ["` `<< slow_ptr->data << ``"]"` `<< endl;` `        ``}` `    ``}` `};`   `// Driver Code` `int` `main(){` `    ``class` `Node *head = NULL;` `    ``class` `NodeOperation *temp = ``new` `NodeOperation();` `    ``for``(``int` `i=5; i>0; i--){` `        ``temp->pushNode(&head, i);` `        ``temp->printNode(head);` `        ``temp->printMiddle(head);` `    ``}` `    ``return` `0;` `}`

## C

 `// C program to find middle of linked list` `#include ` `#include `   `/* Link list node */` `struct` `Node ` `{ ` `    ``int` `data; ` `    ``struct` `Node* next; ` `}; `   `/* Function to get the middle of the linked list*/` `void` `printMiddle(``struct` `Node *head) ` `{ ` `    ``struct` `Node *slow_ptr = head; ` `    ``struct` `Node *fast_ptr = head; `   `    ``if` `(head!=NULL) ` `    ``{ ` `        ``while` `(fast_ptr != NULL && fast_ptr->next != NULL) ` `        ``{ ` `            ``fast_ptr = fast_ptr->next->next; ` `            ``slow_ptr = slow_ptr->next; ` `        ``} ` `        ``printf``(``"The middle element is [%d]\n\n"``, slow_ptr->data); ` `    ``} ` `} `   `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; ` `} `   `// A utility function to print a given linked list ` `void` `printList(``struct` `Node *ptr) ` `{ ` `    ``while` `(ptr != NULL) ` `    ``{ ` `        ``printf``(``"%d->"``, ptr->data); ` `        ``ptr = ptr->next; ` `    ``} ` `    ``printf``(``"NULL\n"``); ` `} `   `/* Driver program to test above function*/` `int` `main() ` `{ ` `    ``/* Start with the empty list */` `    ``struct` `Node* head = NULL; ` `    ``int` `i; `   `    ``for` `(i=5; i>0; i--) ` `    ``{ ` `        ``push(&head, i); ` `        ``printList(head); ` `        ``printMiddle(head); ` `    ``} `   `    ``return` `0; ` `} `

## Java

 `// Java program to find middle of linked list` `class` `LinkedList` `{` `    ``Node head; ``// head of linked list`   `    ``/* Linked list node */` `    ``class` `Node` `    ``{` `        ``int` `data;` `        ``Node next;` `        ``Node(``int` `d)` `        ``{` `            ``data = d;` `            ``next = ``null``;` `        ``}` `    ``}`   `    ``/* Function to print middle of linked list */` `    ``void` `printMiddle()` `    ``{` `        ``Node slow_ptr = head;` `        ``Node fast_ptr = head;` `        `  `            ``while` `(fast_ptr != ``null` `&& fast_ptr.next != ``null``)` `            ``{` `                ``fast_ptr = fast_ptr.next.next;` `                ``slow_ptr = slow_ptr.next;` `            ``}` `            ``System.out.println(``"The middle element is ["` `+` `                                ``slow_ptr.data + ``"] \n"``);` `        `  `    ``}`   `    ``/* Inserts a new Node at front of the list. */` `    ``public` `void` `push(``int` `new_data)` `    ``{` `        ``/* 1 & 2: Allocate the Node &` `                  ``Put in the data*/` `        ``Node new_node = ``new` `Node(new_data);`   `        ``/* 3. Make next of new Node as head */` `        ``new_node.next = head;`   `        ``/* 4. Move the head to point to new Node */` `        ``head = new_node;` `    ``}`   `    ``/* This function prints contents of linked list` `       ``starting from  the given node */` `    ``public` `void` `printList()` `    ``{` `        ``Node tnode = head;` `        ``while` `(tnode != ``null``)` `        ``{` `            ``System.out.print(tnode.data+``"->"``);` `            ``tnode = tnode.next;` `        ``}` `        ``System.out.println(``"NULL"``);` `    ``}`   `    ``public` `static` `void` `main(String [] args)` `    ``{` `        ``LinkedList llist = ``new` `LinkedList();` `        ``for` `(``int` `i=``5``; i>``0``; --i)` `        ``{` `            ``llist.push(i);` `            ``llist.printList();` `            ``llist.printMiddle();` `        ``}` `    ``}` `}` `// This code is contributed by Rajat Mishra`

## C#

 `// C# program to find middle of linked list` `using` `System;`   `class` `LinkedList{` `    `  `// Head of linked list  ` `Node head; `   `// Linked list node ` `class` `Node` `{` `    ``public` `int` `data;` `    ``public` `Node next;` `    `  `    ``public` `Node(``int` `d)` `    ``{` `        ``data = d;` `        ``next = ``null``;` `    ``}` `}`   `// Function to print middle of linked list` `void` `printMiddle()` `{` `    ``Node slow_ptr = head;` `    ``Node fast_ptr = head;` `    `  `    ``if` `(head != ``null``)` `    ``{` `        ``while` `(fast_ptr != ``null` `&&` `               ``fast_ptr.next != ``null``)` `        ``{` `            ``fast_ptr = fast_ptr.next.next;` `            ``slow_ptr = slow_ptr.next;` `        ``}` `        ``Console.WriteLine(``"The middle element is ["` `+` `                          ``slow_ptr.data + ``"] \n"``);` `    ``}` `}`   `// Inserts a new Node at front of the list. ` `public` `void` `push(``int` `new_data)` `{` `    `  `    ``/* 1 & 2: Allocate the Node &` `              ``Put in the data*/` `    ``Node new_node = ``new` `Node(new_data);`   `    ``/* 3. Make next of new Node as head */` `    ``new_node.next = head;`   `    ``/* 4. Move the head to point to new Node */` `    ``head = new_node;` `}`   `// This function prints contents of linked ` `// list starting from  the given node ` `public` `void` `printList()` `{` `    ``Node tnode = head;` `    ``while` `(tnode != ``null``)` `    ``{` `        ``Console.Write(tnode.data + ``"->"``);` `        ``tnode = tnode.next;` `    ``}` `    ``Console.WriteLine(``"NULL"``);` `}`   `// Driver code` `static` `public` `void` `Main()` `{` `    ``LinkedList llist = ``new` `LinkedList();` `    ``for``(``int` `i = 5; i > 0; --i)` `    ``{` `        ``llist.push(i);` `        ``llist.printList();` `        ``llist.printMiddle();` `    ``}` `}` `}`   `// This code is contributed by Dharanendra L V.`

## Python3

 `# Python3 program to find middle of linked list` `# Node class ` `class` `Node: ` `  `  `    ``# Function to initialise the node object ` `    ``def` `__init__(``self``, data): ` `        ``self``.data ``=` `data  ``# Assign data ` `        ``self``.``next` `=` `None`  `# Initialize next as null ` `  `  `  `  `# Linked List class contains a Node object ` `class` `LinkedList: ` `  `  `    ``# Function to initialize head ` `    ``def` `__init__(``self``): ` `        ``self``.head ``=` `None`   `    ``# Function to insert a new node at the beginning  ` `    ``def` `push(``self``, new_data):  ` `        ``new_node ``=` `Node(new_data)  ` `        ``new_node.``next` `=` `self``.head  ` `        ``self``.head ``=` `new_node`   `    ``# Print the linked list` `    ``def` `printList(``self``):` `        ``node ``=` `self``.head` `        ``while` `node:` `            ``print``(``str``(node.data) ``+` `"->"``, end``=``"")` `            ``node ``=` `node.``next` `        ``print``(``"NULL"``)`   `    ``# Function that returns middle.` `    ``def` `printMiddle(``self``):` `        ``# Initialize two pointers, one will go one step a time (slow), another two at a time (fast)` `        ``slow ``=` `self``.head` `        ``fast ``=` `self``.head`   `        ``# Iterate till fast's next is null (fast reaches end)` `        ``while` `fast ``and` `fast.``next``:` `            ``slow ``=` `slow.``next` `            ``fast ``=` `fast.``next``.``next` `        `  `        ``# return the slow's data, which would be the middle element.` `        ``print``(``"The middle element is "``, slow.data)`   `# Code execution starts here ` `if` `__name__``=``=``'__main__'``: ` `  `  `    ``# Start with the empty list ` `    ``llist ``=` `LinkedList() ` `  `  `    ``for` `i ``in` `range``(``5``, ``0``, ``-``1``):` `        ``llist.push(i)` `        ``llist.printList()` `        ``llist.printMiddle()`   ` ``# Code is contributed by Kumar Shivam (kshivi99)`

## Javascript

 ``

Output
```5->NULL
The middle element is 

4->5->NULL
The middle element is 

3->4->5->NULL
The middle element is 

2->3->4->5->NULL
The middle element is 

1->2->3->4->5->NULL
The middle element is ```

Method 3:
Initialize mid element as head and initialize a counter as 0. Traverse the list from head, while traversing increment the counter and change mid to mid->next whenever the counter is odd. So the mid will move only half of the total length of the list.
Thanks to Narendra Kangralkar for suggesting this method.

## C++

 `#include ` `using` `namespace` `std;`   `// Link list node ` `struct` `node` `{` `    ``int` `data;` `    ``struct` `node* next;` `};`   `// Function to get the middle of` `// the linked list` `void` `printMiddle(``struct` `node* head)` `{` `    ``int` `count = 0;` `    ``struct` `node* mid = head;`   `    ``while` `(head != NULL)` `    ``{` `        `  `        ``// Update mid, when 'count'` `        ``// is odd number ` `        ``if` `(count & 1)` `            ``mid = mid->next;`   `        ``++count;` `        ``head = head->next;` `    ``}`   `    ``// If empty list is provided ` `    ``if` `(mid != NULL)` `        ``printf``(``"The middle element is [%d]\n\n"``, ` `                ``mid->data);` `}`   `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;` `}`   `// A utility function to print ` `// a given linked list` `void` `printList(``struct` `node* ptr)` `{` `    ``while` `(ptr != NULL)` `    ``{` `        ``printf``(``"%d->"``, ptr->data);` `        ``ptr = ptr->next;` `    ``}` `    ``printf``(``"NULL\n"``);` `}`   `// Driver code` `int` `main()` `{` `    `  `    ``// Start with the empty list ` `    ``struct` `node* head = NULL;` `    ``int` `i;`   `    ``for``(i = 5; i > 0; i--) ` `    ``{` `        ``push(&head, i);` `        ``printList(head);` `        ``printMiddle(head);` `    ``}` `    ``return` `0;` `}`   `// This code is contributed by ac121102`

## C

 `#include ` `#include `   `/* Link list node */` `struct` `node {` `    ``int` `data;` `    ``struct` `node* next;` `};`   `/* Function to get the middle of the linked list*/` `void` `printMiddle(``struct` `node* head)` `{` `    ``int` `count = 0;` `    ``struct` `node* mid = head;`   `    ``while` `(head != NULL) {` `        ``/* update mid, when 'count' is odd number */` `        ``if` `(count & 1)` `            ``mid = mid->next;`   `        ``++count;` `        ``head = head->next;` `    ``}`   `    ``/* if empty list is provided */` `    ``if` `(mid != NULL)` `        ``printf``(``"The middle element is [%d]\n\n"``, mid->data);` `}`   `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;` `}`   `// A utility function to print a given linked list` `void` `printList(``struct` `node* ptr)` `{` `    ``while` `(ptr != NULL) {` `        ``printf``(``"%d->"``, ptr->data);` `        ``ptr = ptr->next;` `    ``}` `    ``printf``(``"NULL\n"``);` `}`   `/* Driver program to test above function*/` `int` `main()` `{` `    ``/* Start with the empty list */` `    ``struct` `node* head = NULL;` `    ``int` `i;`   `    ``for` `(i = 5; i > 0; i--) {` `        ``push(&head, i);` `        ``printList(head);` `        ``printMiddle(head);` `    ``}`   `    ``return` `0;` `}`

## Java

 `class` `GFG{`   `static` `Node head;`   `// Link list node` `class` `Node` `{` `    ``int` `data;` `    ``Node next;`   `    ``// Constructor` `    ``public` `Node(Node next, ``int` `data)` `    ``{` `        ``this``.data = data;` `        ``this``.next = next;` `    ``}` `}`   `// Function to get the middle of ` `// the linked list` `void` `printMiddle(Node head)` `{` `    ``int` `count = ``0``;` `    ``Node mid = head;`   `    ``while` `(head != ``null``)` `    ``{`   `        ``// Update mid, when 'count' ` `        ``// is odd number ` `        ``if` `((count % ``2``) == ``1``)` `            ``mid = mid.next;`   `        ``++count;` `        ``head = head.next;` `    ``}`   `    ``// If empty list is provided ` `    ``if` `(mid != ``null``)` `        ``System.out.println(``"The middle element is ["` `+` `                            ``mid.data + ``"]\n"``);` `}`   `void` `push(Node head_ref, ``int` `new_data)` `{` `    `  `    ``// Allocate node ` `    ``Node new_node = ``new` `Node(head_ref, new_data);`   `    ``// Move the head to point to the new node ` `    ``head = new_node;` `}`   `// A utility function to print a ` `// given linked list` `void` `printList(Node head)` `{` `    ``while` `(head != ``null``)` `    ``{` `        ``System.out.print(head.data + ``"-> "``);` `        ``head = head.next;` `    ``}` `    ``System.out.println(``"null"``);` `}`   `// Driver code` `public` `static` `void` `main(String[] args)` `{` `    ``GFG ll = ``new` `GFG();`   `    ``for``(``int` `i = ``5``; i > ``0``; i--) ` `    ``{` `        ``ll.push(head, i);` `        ``ll.printList(head);` `        ``ll.printMiddle(head);` `    ``}` `}` `}`   `// This code is contributed by mark_3`

## Python3

 `# Node class ` `class` `Node: ` `   `  `    ``# Function to initialise the node object ` `    ``def` `__init__(``self``, data): ` `        ``self``.data ``=` `data  ``# Assign data ` `        ``self``.``next` `=` `None`  `# Initialize next as null ` `   `  `# Linked List class contains a Node object ` `class` `LinkedList: ` `   `  `    ``# Function to initialize head ` `    ``def` `__init__(``self``): ` `        ``self``.head ``=` `None` ` `  `    ``# Function to insert a new node at the beginning  ` `    ``def` `push(``self``, new_data):  ` `        ``new_node ``=` `Node(new_data)  ` `        ``new_node.``next` `=` `self``.head  ` `        ``self``.head ``=` `new_node` ` `  `    ``# Print the linked list` `    ``def` `printList(``self``):` `        ``node ``=` `self``.head` `        ``while` `node:` `            ``print``(``str``(node.data) ``+` `"->"``, end ``=` `"")` `            ``node ``=` `node.``next` `        ``print``(``"NULL"``)` ` `  `    ``# Function to get the middle of` `    ``#  the linked list` `    ``def` `printMiddle(``self``):` `        ``count ``=` `0` `        ``mid ``=` `self``.head` `        ``heads ``=` `self``.head` `  `  `        ``while``(heads !``=` `None``):` `      `  `        ``# Update mid, when 'count'` `        ``# is odd number ` `            ``if` `count&``1``:` `                ``mid ``=` `mid.``next` `            ``count ``+``=` `1` `            ``heads ``=` `heads.``next` `            `  `        ``# If empty list is provided ` `        ``if` `mid!``=``None``:` `            ``print``(``"The middle element is "``, mid.data)` ` `  `# Code execution starts here ` `if` `__name__``=``=``'__main__'``: ` `   `  `    ``# Start with the empty list ` `    ``llist ``=` `LinkedList() ` `   `  `    ``for` `i ``in` `range``(``5``, ``0``, ``-``1``):` `        ``llist.push(i)` `        ``llist.printList()` `        ``llist.printMiddle()` ` `  ` ``# This Code is contributed by Manisha_Ediga`

## C#

 `using` `System;`   `public` `class` `GFG` `{`   `    ``static` `Node head;`   `    ``// Link list node` `    ``public`   ` ``class` `Node {` `        ``public`   ` ``int` `data;` `        ``public`   ` ``Node next;`   `        ``// Constructor` `        ``public` `Node(Node next, ``int` `data) {` `            ``this``.data = data;` `            ``this``.next = next;` `        ``}` `    ``}`   `    ``// Function to get the middle of` `    ``// the linked list` `    ``void` `printMiddle(Node head) {` `        ``int` `count = 0;` `        ``Node mid = head;`   `        ``while` `(head != ``null``) {`   `            ``// Update mid, when 'count'` `            ``// is odd number` `            ``if` `((count % 2) == 1)` `                ``mid = mid.next;`   `            ``++count;` `            ``head = head.next;` `        ``}`   `        ``// If empty list is provided` `        ``if` `(mid != ``null``)` `            ``Console.WriteLine(``"The middle element is ["` `+ mid.data + ``"]\n"``);` `    ``}`   `    ``public` `void` `Push(Node head_ref, ``int` `new_data) {`   `        ``// Allocate node` `        ``Node new_node = ``new` `Node(head_ref, new_data);`   `        ``// Move the head to point to the new node` `        ``head = new_node;` `    ``}`   `    ``// A utility function to print a` `    ``// given linked list` `    ``void` `printList(Node head) {` `        ``while` `(head != ``null``) {` `            ``Console.Write(head.data + ``"-> "``);` `            ``head = head.next;` `        ``}` `        ``Console.WriteLine(``"null"``);` `    ``}`   `    ``// Driver code` `    ``public` `static` `void` `Main(String[] args) {` `        ``GFG ll = ``new` `GFG();`   `        ``for` `(``int` `i = 5; i > 0; i--) {` `            ``ll.Push(head, i);` `            ``ll.printList(head);` `            ``ll.printMiddle(head);` `        ``}` `    ``}` `}`     `// This code is contributed by Rajput-Ji `

## Javascript

 ``

Output
```5->NULL
The middle element is 

4->5->NULL
The middle element is 

3->4->5->NULL
The middle element is 

2->3->4->5->NULL
The middle element is 

1->2->3->4->5->NULL
The middle element is ```