# Check whether the length of given linked list is Even or Odd

• Difficulty Level : Basic
• Last Updated : 13 May, 2021

Given a linked list, the task is to make a function which checks whether the length of the linked list is even or odd.
Examples:

```Input : 1->2->3->4->NULL
Output : Even

Input : 1->2->3->4->5->NULL
Output : Odd```

Method 1: Count the codes linearly
Traverse the entire Linked List and keep counting the number of nodes. As soon as the loop is finished, we can check if the count is even or odd. You may try it yourself.
Method 2: Stepping 2 nodes at a time
Approach:

```1. Take a pointer and move that pointer two nodes at a time
2. At the end, if the pointer is NULL then length is Even, else Odd.```

## C++

 `// C++ program to check length``// of a given linklist``#include ``using` `namespace` `std;` `// Defining structure``class` `Node``{``    ``public``:``    ``int` `data;``    ``Node* next;``};` `// Function to check the length of linklist``int` `LinkedListLength(Node* head)``{``    ``while` `(head && head->next)``    ``{``        ``head = head->next->next;``    ``}``    ``if` `(!head)``        ``return` `0;``    ``return` `1;``}``    ` `// Push function``void` `push(Node** head, ``int` `info)``{``    ``// Allocating node``    ``Node* node = ``new` `Node();``    ` `    ``// Info into node``    ``node->data = info;``    ` `    ``// Next of new node to head``    ``node->next = (*head);` `    ``// head points to new node``    ``(*head) = node;``}` `// Driver code``int` `main(``void``)``{``    ``Node* head = NULL;``    ` `    ``// Adding elements to Linked List``    ``push(&head, 4);``    ``push(&head, 5);``    ``push(&head, 7);``    ``push(&head, 2);``    ``push(&head, 9);``    ``push(&head, 6);``    ``push(&head, 1);``    ``push(&head, 2);``    ``push(&head, 0);``    ``push(&head, 5);``    ``push(&head, 5);``    ``int` `check = LinkedListLength(head);``    ` `    ``// Checking for length of``    ``// linklist``    ``if``(check == 0)``    ``{``        ``cout << ``"Even\n"``;``    ``}``    ``else``    ``{``        ``cout << ``"Odd\n"``;``    ``}``    ``return` `0;``}` `// This is code is contributed by rathbhupendra`

## C

 `// C program to check length``// of a given linklist``#include``#include` `// Defining structure``struct` `Node``{``    ``int` `data;``    ``struct` `Node* next;``};` `// Function to check the length of linklist``int` `LinkedListLength(``struct` `Node* head)``{``    ``while` `(head && head->next)``    ``{``        ``head = head->next->next;``    ``}``    ``if` `(!head)``        ``return` `0;``    ``return` `1;``}``    ` `// Push function``void` `push(``struct` `Node** head, ``int` `info)``{``    ``// Allocating node``    ``struct` `Node* node = (``struct` `Node*) ``malloc``(``sizeof``(``struct` `Node));``    ` `    ``// Info into node``    ``node->data = info;``    ` `    ``// Next of new node to head``    ``node->next = (*head);` `    ``// head points to new node``    ``(*head) = node;``}` `// Driver function``int` `main(``void``)``{``    ``struct` `Node* head = NULL;``    ` `    ``// Adding elements to Linked List``    ``push(&head, 4);``    ``push(&head, 5);``    ``push(&head, 7);``    ``push(&head, 2);``    ``push(&head, 9);``    ``push(&head, 6);``    ``push(&head, 1);``    ``push(&head, 2);``    ``push(&head, 0);``    ``push(&head, 5);``    ``push(&head, 5);``    ``int` `check = LinkedListLength(head);``    ` `    ``// Checking for length of``    ``// linklist``    ``if``(check == 0)``    ``{``        ``printf``(``"Even\n"``);``    ``}``    ``else``    ``{``        ``printf``(``"Odd\n"``);``    ``}``    ``return` `0;``}`

## Java

 `/*package whatever //do not write package name here */` `import` `java.io.*;` `// Java program to check length``// of a given linklist``class` `GfG``{` `// Defining structure``static` `class` `Node``{``    ``int` `data;``    ``Node next;``}` `// Function to check the length of linklist``static` `int` `LinkedListLength(Node head)``{``    ``while` `(head != ``null` `&& head.next != ``null``)``    ``{``        ``head = head.next.next;``    ``}``    ``if` `(head == ``null``)``        ``return` `0``;``    ``return` `1``;``}``    ` `// Push function``static` `void` `push(Node head, ``int` `info)``{``    ``// Allocating node``    ``Node node = ``new` `Node();``    ` `    ``// Info into node``    ``node.data = info;``    ` `    ``// Next of new node to head``    ``node.next = (head);` `    ``// head points to new node``    ``(head) = node;``}` `// Driver code``public` `static` `void` `main(String[] args)``{``    ``Node head = ``null``;``    ` `    ``// Adding elements to Linked List``    ``push(head, ``4``);``    ``push(head, ``5``);``    ``push(head, ``7``);``    ``push(head, ``2``);``    ``push(head, ``9``);``    ``push(head, ``6``);``    ``push(head, ``1``);``    ``push(head, ``2``);``    ``push(head, ``0``);``    ``push(head, ``5``);``    ``push(head, ``5``);``    ``int` `check = LinkedListLength(head);``    ` `    ``// Checking for length of``    ``// linklist``    ``if``(check == ``0``)``    ``{``        ``System.out.println(``"Odd"``);``    ``}``    ``else``    ``{``        ``System.out.println(``"Even"``);``    ``}``}``}` `// This code is contributed by Prerna saini`

## Python3

 `# Python program to check length``# of a given linklist` `# Defining structure``class` `Node:``    ``def` `__init__(``self``, d):``        ``self``.data ``=` `d``        ``self``.``next` `=` `None``        ``self``.head ``=` `None` `    ``# Function to check the length of linklist``    ``def` `LinkedListLength(``self``):``        ``while` `(``self``.head !``=` `None` `and` `self``.head.``next` `!``=` `None``):``            ``self``.head ``=` `self``.head.``next``.``next``            ` `        ``if``(``self``.head ``=``=` `None``):``            ``return` `0``        ``return` `1``    ` `    ``# Push function``    ``def` `push(``self``, info):``        ` `    ``# Allocating node``        ``node ``=` `Node(info)` `    ``# Next of new node to head``        ``node.``next` `=` `(``self``.head)` `    ``# head points to new node``        ``(``self``.head) ``=` `node` `# Driver code` `head ``=` `Node(``0``)``    ` `# Adding elements to Linked List``head.push( ``4``)``head.push( ``5``)``head.push( ``7``)``head.push( ``2``)``head.push( ``9``)``head.push( ``6``)``head.push( ``1``)``head.push( ``2``)``head.push( ``0``)``head.push( ``5``)``head.push( ``5``)``check ``=` `head.LinkedListLength()``    ` `# Checking for length of``# linklist``if``(check ``=``=` `0``) :``    ``print``(``"Even"``)``else``:``    ``print``(``"Odd"``)` `# This code is contributed by Prerna saini`

## C#

 `// C# program to check length``// of a given linklist``using` `System;` `class` `GfG``{` `// Defining structure``class` `Node``{``    ``public` `int` `data;``    ``public` `Node next;``}` `// Function to check the length of linklist``static` `int` `LinkedListLength(Node head)``{``    ``while` `(head != ``null` `&& head.next != ``null``)``    ``{``        ``head = head.next.next;``    ``}``    ``if` `(head == ``null``)``        ``return` `0;``    ``return` `1;``}``    ` `// Push function``static` `void` `push(Node head, ``int` `info)``{``    ``// Allocating node``    ``Node node = ``new` `Node();``    ` `    ``// Info into node``    ``node.data = info;``    ` `    ``// Next of new node to head``    ``node.next = (head);` `    ``// head points to new node``    ``(head) = node;``}` `// Driver code``public` `static` `void` `Main()``{``    ``Node head = ``null``;``    ` `    ``// Adding elements to Linked List``    ``push(head, 4);``    ``push(head, 5);``    ``push(head, 7);``    ``push(head, 2);``    ``push(head, 9);``    ``push(head, 6);``    ``push(head, 1);``    ``push(head, 2);``    ``push(head, 0);``    ``push(head, 5);``    ``push(head, 5);``    ``int` `check = LinkedListLength(head);``    ` `    ``// Checking for length of``    ``// linklist``    ``if``(check == 0)``    ``{``        ``Console.WriteLine(``"Odd"``);``    ``}``    ``else``    ``{``        ``Console.WriteLine(``"Even"``);``    ``}``}``}` `// This code has been contributed``// by PrinciRaj1992`

## Javascript

 ``

Output:

`Odd`

Time Complexity: O(n)
Space Complexity: O(1)

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