algorithm: find the middle of linked-list #1096

Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,27 @@
	/**
	* A LinkedList based solution for finding middle node of linked list.
	* https://afteracademy.com/blog/middle-of-the-linked-list
	*/
	class MiddleOfLL {
	solution (head) {
	/*
	Problem Statement:
	Given the head of a singly linked list, return the middle node of the linked list.
	If there are two middle nodes, return the second middle node.

	Link for the Problem: https://leetcode.com/problems/middle-of-the-linked-list/
	*/
	let fast = head
	let slow = head

	if (head.next == null) { return head }
10kartik marked this conversation as resolved. Show resolved Hide resolved

	while (fast != null && fast.next != null) {
	fast = fast.next.next
	slow = slow.next
	}
	return slow
	}
	}

	export { MiddleOfLL }

Show comments View file Open in desktop

Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,41 @@
	import { MiddleOfLL } from '../MiddleOfLinkedList'
	import { LinkedList } from '../SinglyLinkedList'

	describe('MiddleOfLinkedList', () => {
	it('middle node Of linked list - even length ', () => {
	const list = new LinkedList()
	list.addFirst(1)
	list.addLast(2)
	list.addLast(3)
	list.addLast(4)
	list.addLast(5)
	list.addLast(6)
	list.addLast(7)

	const MiddleNodeOfLinkedList = new MiddleOfLL().solution(list.headNode)
	expect(MiddleNodeOfLinkedList.data).toEqual(4)
	})

	it('middle node of linked list - odd length ', () => {
	const list = new LinkedList()
	list.addFirst(10)
	list.addLast(20)
	list.addLast(30)
	list.addLast(40)
	list.addLast(50)
	list.addLast(60)
	list.addLast(70)
	list.addLast(80)

	const MiddleNodeOfLinkedList = new MiddleOfLL().solution(list.headNode)
	expect(MiddleNodeOfLinkedList.data).toEqual(50)
	})

	it('middle node of linked list - length 1 ', () => {
	const list = new LinkedList()
	list.addFirst(100)

	const MiddleNodeOfLinkedList = new MiddleOfLL().solution(list.headNode)
	expect(MiddleNodeOfLinkedList.data).toEqual(100)
	})
	})

Navigation Menu