Detect loop in linked list(floyd algo / Tortoise and hare algo)

[@azeeztaiwo2802]

I really like the way you explain the algorithm, so calm and straight to point

[@leopoldroitel4022]

So basically unless you know Floyd's algorithm, you can't come this up with this by yourself.

[@GKALYAN04]

Btw, You can use Hash Tables which has the same time complexity as Floyd's algo.

[@the_chi]

@@GKALYAN04 but not the same space complexity

[@krisnadiputra93]

lol, it s not true, at least Floyd could

[@TonyDemetriou]

You probably could come up with it yourself if you are thinking about it the right way. For me, if I think about a loop where I want to walk around it and stop on the same square I started on, then I would probably want to use the second pointer to stay still and when they're equal again we have reached the start. If you then said I have to move both pointers I might think of moving the second one at double speed so it will do two loops and be at the start when the first pointer reaches the start. After that, I can figure out how to start with a chain that becomes a cycle, but they wouldn't meet at the right square, and I'd think about how with the loop I started both pointers together, but with the chain one pointer has a headstart by the time the other starts on the loop. If the headstart is 2, then it will meet up 2 steps too early. That would tell me that the number of steps to the start of the loop is the same as the number of steps in the chain, but I don't know what that number is. But if we take the same number of steps along the chain and the remaining loop we will meet at the start of the loop. Then I would think about unusual situations, like when there's an even vs odd number of steps, or what if the chain is much longer than the loop, or the loop is much longer than the chain. ... So I'd probably get to the right answer, but ONLY because of the way I started thinking about it, and because of the questions getting asked. If I was just programming and wanted to loop around to the start, then I wouldn't need to move the second pointer, and I wouldn't be thinking about the rest and wouldn't figure out that you can detect cycles like this. Or if you just gave me a list of nodes and asked me to check if there are cycles, I'd probably start thinking about starting from the beginning of the chain rather than starting with the loop, and I personally probably would not figure it out. People trained in formal mathematics have ways of working through problems like this. I'm unfortunately not one of them - for me, a lot of the time it's whether I'm asking myself the right questions, and that is usually just luck depending on where my mind wanders at that particular moment.

[@karana2260]

if you jog with people in a park, or watch f1, you could come up with this solution.

[@Artshi_Sakshi]

sir ,the way you explain makes it so easy to understand......kudos to your effort!!!!

[@lifekool5838]

Such a simple yet powerful explanation of various algorithms. I hated algos... but now it is fun due to your videos and your positivity is icing on the cake. Thank you sir... for amazing videos.

[@shashankparmar7899]

Great solution sir!!! I have always used unordered map for this. (unordered_map map). But, this solution is very elegant and also requires only O(1) space complexity, unlike unordered_map solution.

[@Cybernetic1]

Sir, I have big fan of yours..... i love the way you explain... the way you talk slow and simplicity in your face.

[@mp0157]

Vivekanand, You kept the explanation quite simple & straightforward! It greatly helped :) Thank you!

[@shivamrajput3321]

the way you explain is very easy to visualize and implement. even a guy like me who gets bamboozled seeing these algorithms is able to keep up. Nice going bro. Hoping for your prosperity

[@nareshtanniru]

Thanks For video. To find start of loop here is another alternative after p and q meet. we will make q pointer stop at that point and make p pointer move till it reaches q pointer again and count number of nodes in loop. this will give us length of cycle. ( how many nodes are in cycle). lets denote dis with c. then just take 2 pointers p1 and p2 at c distance apart.. and move both at SAME speed till p1 and p2 meets. that point will be start of loop.

[@zippy.gaurav]

Thank you for posting your videos free of cost. I really am thankful to you.

[@PaulFromMalta]

REALLY AWESOME EXPLANATION!!! Thank you so much for taking the time to make this video. 9 mins and 28 seconds of no bullshit, and just fundamental basic concepts built on top of each other in a crystal clear way. Please keep making vids!!!!

[@joemoe5954]

Thank you! This helped me understand how to detect a loop within a link list quickly and in an understandable manner!

[@vivekanandkhyade]

Thanks Joseph...!

[@adityapaithon6499]

What's the time complexity of this approach

[@vaibhavlaxman4959]

@@adityapaithon6499 O(n)

[@fahim.m.choudhury]

Thank you very much! Your explanation and teaching are very clear.

[@gin8964]

Very straightforward explanation. Thank you so much!

[@chunkwanchan5503]

Thanks! can I start p pointer at head & q pointer at head.next? I found in some cycle structure, there's infinite loop where 2 pointers will never meet?

[@poojaupadhyay6364]

very clear and concise explaination

[@krisshore2917]

Simplest explanation for this algorithm. Thank you.

[@crazyvlog5830]

🎂🎂🎂🎂🎉🎉🎉🎉🎉🎂

[@RadhamaniRamadoss]

Loved the explanation ..Thankyou sir

[@cppdog3549]

To find the start of the cycle, skip to 6:00

[@sudomoon]

Simply Wonderful Explanation

[@varnanthirugnanasambandan559]

Very clear explanation 🙏

[@nahidulislam9000]

Your video is much more understandable than others.

[@nouru6856]

@Vivekanand your the best!!!! Thumbs upppp

[@gawarivivek]

I'm loving your videos, man!! Clear explanation.. Thanks for sharing your knowledge with us.. Keep it up!!

[@kewtomrao]

Why the haters?So nicely explained......Keep it up!

[@prajwalcr7799]

How will be the linked list already present in our IDE as we are directly checking instead of inputting anything

[@vinaynadig3258]

simple but perfect explanations. Liked it

[@jh9104]

Super clear explanation of the concept. Thank you!

[@mihirjoshi3589]

Your videos are very helpful. Could you please make one for LRU Cache? Superb initiative, thanks a lot!

[@DarshanKumarTV-ur8tw]

satisfactory teaching sir

[@smritidubey5781]

Sir, why q->next!=NULL is considered in the while loop?

[@bisatisrilatha7957]

TQsm sir it was very helpful vedio.

[@PriteshRanjan30]

you have very nicely explained this solution.please Provide dynamic programming video explanation with examples

[@karthikeyaacharya8424]

Awesome and simple explanation !!

[@angelroma5456]

Thank you bro, pretty simple to understand!

[@trestenpool9045]

Great explanation sir, thank you!

[@sankaranarayananh7957]

Awesome explanation sir! Thank you

[@akshayroy6261]

Great Explanation 😀

[@hemantmangwani7172]

Thank you sir . Its Helped a lot.

[@AbhishekSharma-uh8pb]

When you starting again sir . Very good 👍 explanation

[@HarmeetKaur]

Thank you for these videos. Really helpful!

[@priyanshuyadav8173]

You're a great teacher ✨✨

[@Ankit13555]

Can you please explain Brent's Cycle Detection Algorithm ..that will give an edge in interviews

[@anshiknigam671]

while(p && q && q->next) why only we are checking q->next. should we also place p->next also. please clear the doubt, is it important to place q->next in this condition. I think that p && q is enough. if I am wrong please correct me, anyone.

[@nands4410]

Anshik Nigam q is ahead of p by one step so we need to check for q itself.

[@pavankumard5276]

wont this show an error if there is no loop and the linked list consists of 4 nodes. because then p&&q&&q->next is not null but q->next->next=null it will show exception in java

[@AjinkyaWasnik]

Perfectly explained. Whatever questions aroused while watching the video were answered right then and there. :) keep posting videos, sir.

[@jeevan999able]

*arise

[@lotusithok4985]

Best explaination so far...

[@xof8256]

Mast bhava, dhanyawad

[@anirudhbharti3013]

I think for remove_loop while(p->Next!=q->Next) should be the condition

[@vighneshk509]

sir in while loop you said anyone of those condition but that is AND operator so all condition must be satisfied not just one of them

[@simonwathigo604]

I think it was just a mistake. Having a nil value will raise an runtime error `cant access next attribute for 'nil' value`.

[@ayushikumar34]

Thanks a lot for a great explanation .. keep up your good wrk ... you are really good

[@sunnyjain630]

very nice expland should we have p=p->next and q=q->next->next in case of removal of loop detected by detection algo in step1 plz clear my doubt any one.... thanks in adv

[@nands4410]

I am no expert but I would maintain a previous pointer to p say "previous" and when we detect the start of loop i would set the previous-next->NULL. This would remove the loop.

[@ayushikumar34]

yes true ..what is written on board is wrong ..probably coz of which he didnt explain ...it shud be q->next->next

[@AddieInGermany]

Sir i cannot find Floyd Algo.. Can you please provide the link ?

[@srinivasanshanmugam9527]

Pls post the video for reversing the doubly linked lists

[@kingdey9136]

Thank you!

[@chhamasahu5987]

Hello ,sir can you give us the link for the explanation on why this algorithm work.I couldn't find it on your channel.

[@vivekanandkhyade]

"Why floyd's cycle detection algorithm works? " on this channel. Please check. Thanks.

[@ranjanasinha]

Loved it. Thanks a lot.

[@hitec1691]

India!! :)

[@santoshreddy9963]

Sir slow pointer null condition check karne ki zaroor nhi he.

[@kanakadasyankor]

Hi Vivek .. Awesome..thanks a lot.. any videos on Graphs ?

[@vivekanandkhyade]

Thanks Kanakadas.......sure will soon start a series on Graphs...!

[@rashmikiranpandit8962]

I hit subscribe cuz your innocent way of asking us to subscribe was so cutee..:)

[@madhavikatta7346]

Thank you sir

[@arvindkumarsharma5536]

Well explained as always..

[@ankurrohilla4655]

Sir,why u stop uploading videos!!!!!!!!! u r the best

[@anandkulkarni2111]

10 /10 explanation kudos!!

[@anilkumaryadavchimaldhari7695]

Simply super

[@karynayehorova606]

Awesome. Thank you.

[@ShivamKendre-fc3su]

Greay explanation!! keep it up

[@mannankathuria8879]

Count the number of nodes in a link list program please

[@mainulhasan136]

You are too good..

[@deepakborah8335]

Congratulations for making good video. Upload videos series on Merg,Quick and Radix sort algorithm and program.

[@engineersride8273]

Hello Vivekanand, please do upload a video on how to remove the loop from linked list

[@vivekanandkhyade]

very sooon...! Thanks..!

[@jeeveshrawal2576]

Plz can u explain detection of loop in doubly linked list

[@jaysahu357]

Very nice sir

[@chandralekha7717]

Great video thanks

[@RahulKumar-qu1if]

Sir what is the time complexity of this prog.

[@vishalvikram8637]

O(n)

[@Jarikraider]

You probably want to ensure that q->next and q->next->next are not null in that order.

[@mritunjaymishra5008]

If there isn't a loop...then won't it run infinitely?🤔

[@amanbajpai9513]

it will null terminate

[@fares.abuali]

Thanks ❤

[@gunjankumar7970]

sir plze upload some important programming interview questions of binary search tree ....it's being difficult to understand due to recursion

[@anuragsahoo1235]

let just say there is cycle between two node then it is better to check first then iterate.

[@anilbharath1994]

It's really helped me a lot

[@vivekanandkhyade]

Thanks Anil...!

[@ill-fatedstranger447]

Many many thanks

[@sudhak8569]

Sir i cannot find full code in github...Can you please provide the link ?

[@induroopa627]

Thanks a ton 👍🏻😍

[@srinivasanshanmugam9527]

Also please post detecting loop in doubly linked list

[@carlosalba9690]

This amazing!!!!!!

[@musicmania4609]

Good job

[@vishnuvardhan-md1ux]

bro please post more videos thank you for your videos and the help

[@payalsagar1808]

great🙌

[@uvenkatasaiswaroop2425]

Boss , You r Awesome !!!

[@Kaushikvel]

If you don't understand from this video, you will never understand from anywhere else.

[@mayank.ranjan]

true

[@adityapaithon6499]

What's the time complexity of this btw

[@pymondo1147]

hahaha absolutely true.. No one can give this much explanation. If people are still finding it difficult then they should find other jobs:-p

[@aakash.nagpal98]

land le

[@aarushiahuja3875]

Sir kindly explain the program of this topic you have provided on github , thank you in advance :)

[@ankitvarmait]

Thanks Sir

[@dhritisinha8377]

Narsimha karumanchi ki book ka exact code chapa h

[@AddieInGermany]

Sir where is the next video, i can't find it.

[@vivekanandkhyade]

Hey I am sorry Aditya...I forgot to upload the video...I will upload the video soon...!

[@AddieInGermany]

No problem sir. I found the solution on geeksforgeeks.

[@MrPraveenBasavaraj]

where is ur next video. can't find

[@vivekanandkhyade]

"Why floyd's cycle detection algorithm works? " on this channel. Please check. Thanks.

[@graingert]

"I will execute the code parallely": *executes code sequentially*

[@salonirathi1158]

Awesome video :))

[@ratmgant]

goat