Find Middle of a Linked List

Problem Statement

Given a 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.

DEMO

https://sauravhathi.github.io/find-middle-of-the-linked-list

SCREENSHOTS

1. Home Page

2. Input Page and Output Page

Algorithm

1. Initialize two pointers, fast and slow, to the head of the linked list.
2. Move fast two nodes and slow one node at a time.
3. When fast reaches the end of the linked list, slow will be at the middle of the linked list.

Functions

getList()

This function returns the list entered by the user.

validateArray(list)

This function validates the list entered by the user. It returns true if the list is valid and false if the list is invalid.

reset()

This function resets the page.

Node(data)

This function creates a node for the linked list.

LinkedList()

This function creates a linked list.

add(data)

This function adds a node to the linked list.

Node findMiddle()

This function finds the middle of the linked list and returns the middle element.

findMiddle()

This function finds the middle of the linked list and prints the middle element.

Classes

Node

This class creates a node for the linked list.

LinkedList

This class creates a linked list.

Variables

list

This variable stores the list entered by the user.

listError

This variable stores the error message for the list.

resultDiv

This variable stores the result div.

result

This variable stores the result.

linkedList

This variable stores the linked list.

middle

This variable stores the middle element of the linked list.

ul

This variable stores the unordered list.

indexOfListUl

This variable stores the unordered list of the index of the elements.

li

This variable stores the list item.

indexOfListLi

This variable stores the list item of the index of the elements.

temp_index

This variable stores the index of the middle element.

p

This variable stores the paragraph.