Topological Sort | Kahn's Algorithm | Graph Theory

[@puneetkumarsingh1484]

This video is simply great. When I read it first, it took 3-4 hrs to fully understand the algorithm. The video has done the same in 14min.

[@Aldrin32f]

Repeated the same feat, KZbin recommendation to the rescue. PS Thanks @WilliamFiset

[@democreation3594]

@@Aldrin32f did the same and now I am here😁

[@shouryasingh2193]

I just now Solved Course Schedule II on leetcode using this algo

[@williamadams5034]

My favourite ordering is to Keep Sleeping.

[@AtharvaRao0104]

@11:54 : It should be "Afterwards loop through all the *nodes* (not edges) of the graph and add all the nodes with an incoming degree of 0" This is a brilliant series. You teach in concise and clear manner. I first studied graphs in 2003 at college but never understood it and had great fear in the mind for graph problems. I found a great teacher after 21 years and I understand it easily. Thank you very much.

[@geniamartynova8844]

Clean and concise explanation. Easy to comprehend and remember. Thank you!

[@njkevlani]

TIL Superman didn't know topological sort

[@dheerajgopinath1892]

The way you explained is simply superb!! especially the "getting ready for school" example..

[@LUKFUNTV]

Really takes an effort to make it sooooooooooooo SIMPLE🙏🙏🙏🙏🙏🙌🙌🙌🙌🙌

[@m.movsar]

Лучший канал по алгоритмам! Thank you William!

[@KevinDesai]

What an example to start with. Thanks for not starting with gibberish numbers. This makes more sense than all the other videos

[@1hpdell]

William, really appreciate your effort in making this Video! Effort behind this Animation is awesome, explanation is awesome too!

[@abhishektiwari7643]

Was following a course and couldn't understand this concept there but this video was so simple and better explained

[@AbrahamWilson]

Hey William, just wanted to say thank you. If it's possible could you make a series on DP like the one you're doing for graph theory.

[@vedantsharma5876]

That would surely be the best DP course on KZbin. I love how he explains

[@sandeepjnv13]

Not to undermine William but there’s KZbin channel “Inside Code”, he explains lot of concepts pretty well. He has dynamic programming content as well. Also a Udemy course on dynamic programming

[@pelvispresley22]

The freecodecamp video from Alvin Zablan on DP is as good as it gets

[@robaczliwy]

Thank you for a very clear explanation. Implementation was easy once I grasped the concept you've laid out in this video.

[@Sunny-vl1ff]

Thanks! It is great to see how the algorithm works in practice.

[@njww13]

This video helped a lot since before I would constantly wake up in the morning and put on my school before my socks

[@justarandomguyofficial1058]

just looking at the playlists you made motivates me

[@David-fy1sn]

Wow great explanation in only 13 mins!

[@przemekbary]

Thanks a lot for the explanation. You've got a great gift of explaining complicated thing easy (which IMO is the sign of a genius mind)

[@emwistu22]

Your videos and your teaching style are amazing!!

[@mercyomwoyo985]

Thanks William for the visualization and Animation! I clearly understand the concept now!

[@mister_mad]

amazing explanation and visualization of the algorithm! a video unlike no other

[@kartarsingh7776]

That was a great example(dressing up) at the start of video.

[@JeremyIglehart]

Great video. Small suggestion - right at the end where you check if index is not equals to n it would be really nice if you also showed an example of what would happen with your code if there was a cycle in the graph.

[@jamesbon68]

For anyone wondering about this, if you imagine a 3 node cycle, A -> B -> C -> A. Notice that you will never add these nodes to the queue because their indegree will never be 0. This implies that index will also never be larger than n.

[@agnelamodia]

Easy and simple. Marvelous.

[@centr0]

Wow. I understood that. Great way of teaching. You’re amazing. Thank you, sir.

[@leducphuclong]

Thank you so much, I really appreciate your video. Please continue...

[@northridgefield]

Great clarity - quality content.

[@LUKFUNTV]

I recommend this.........to all the before_watching_read_comments_section people 🙌🙌🙌

[@Sauce-ke]

I hope all of my professors are teaching the same as you. I really need a data structure 1 on 1 teacher to teach me everything

[@yamatolowa2256]

this is 1 on 1 teaching i believe

[@zy3749]

Thank you so much, it is the most clear explanation I've found.

[@fantasy9960]

thank you so much William! this is extremely helpful for beginners!

[@shnerdz]

great explanation as always. please make a video on segment trees next! such a powerful yet simple data structure

[@neerajkulkarni6506]

10/10 beautifully explained!

[@avipatel1534]

Thanks this video helped me optimize my sort code for leetcode course scheduling

[@Junposs]

Thank you Wiliam, I finally understand what Topological Sort is!

[@markwillis2336]

I work from home. Why do I even need this getting dressed algorithm again? What an incredible breakdown, thank you so much for simplifying this complex topic so much for complete beginners like me.

[@abhinavboyed6624]

I'm about to binge watch all your videos. Thanks for the awesome content!

[@spicy_wizard]

FANTASTIC. The problem with DFS on topological sort is that the recursion is too expensive, BFS is faster in all other aspects

[@puneetkumarsingh1484]

Alternatively, we can implement the DFS topological sort algo, using stack.

[@Learner010]

Very nice explanation. please make a video on articulation point and bridges

[@twistedlog24]

thanks for explaning this so clearly!!

[@soanonso]

Nicely explained - thanks for this.

[@atharvas4399]

this is 100 times better than my algo professor

[@sstp105]

amazing explanation!

[@mickeynig1]

Thanks Mr. Fiset really awesome explanation

[@NoName-ip4tt]

Animation you conduct has heart beat sound as background. I like it :)

[@lazysky1234]

Thank you for your video, great explanation!

[@babumon5351]

Very nice explanation. Thanks

[@jeehar1]

It was clear, thanks again man

[@nehascorpion]

Awesome content! Thank you for putting in so much effort. Appreciate it!

[@hix0071]

Keep it up William. May you reach million subs next year !

[@mostafaarafa1461]

Thanks, You explained it really perfectly

[@djklsdf-32sdf]

최고의 영상

[@cardel-qq6xp]

Underwear -> pants -> shirt -> hoodie -> socks -> shoes -> school

[@kevintran6102]

Good as always. So easy to understand.

[@jabir5768]

HI ! Really nice explanation but I was wondering about the complexity why is it O(E+V) ? Shouldn't be O(V) since we iteratre of the nodes twice to set the degrees, then the while loop iterates exactly V times ?

[@30天冥想练习]

Kahn : Implements Topological Sort. Superman : Am i a joke to you ? Wears underwear after pants.

[@ksenthu]

Best explanation ever, thank you!

[@algorithmscasts902]

Nice animation and great explanation, thank you

[@m-meier]

This was awesome! Subscribed!

[@shantanubapat6937]

We have to loop through all vertices to find those who have in degree of zero. Can we optimize this using heap or priority queue?

[@WhyAnkurGautam]

We have to loop through once to find the vertices which have indegree of zero and put it in queue. After that we just have to pop the element and decrement in-degree of its dependent nodes. When you are decrementing you can check if it is zero or not. If it is zero than you can put that node into queue. This way you dont need priority queue. Only using queue will work in O(N+E) I guess.

[@jisanson]

Thank you for this awesome video!

[@tanmaykharshikar9419]

This video is a gem, thanks! You have a new fan :)

[@yujianzhao6461]

Thanks a lot man! I really appreciate your work!

[@geomichelon]

great video! Thanks man!

[@ricardo7240]

Awesome, keep it up!

[@VijayKiran225]

beautiful explanation .. keep up the good work.. subscribed as well

[@akshatmehra3951]

You're the best man

[@migzleon4047]

Excellent content.!

[@akidanis6984]

holy shit this was such a great explanation, tysm!!

[@prabhat2342]

wonderful explanation, thanks man:)

[@FaustoCarvalho]

What tool have you used to draw and animate these graphs? Thanks

[@il5083]

Nice video. Is there a reason not to use Kahn's algorithm instead of the DFS topological sort in an interview since this is easier to memorize and code?

[@droy7528]

Thanks a lot, William for all these golden videos. I recently came across Aho- corasick and finding it really difficult to umderstand it properly. So I am commenting on the latest vdo here...hoping u would see my comment. We would be really grateful if u could pull up a vdo on Aho-Corasick. Thanks in advance.

[@soumyajitchatterjee5822]

Beautiful

[@vm7240]

What is the time complexity of calculating indegree? O(V^2) or O(V + E)? V = no of vertices E = no of edges Since there are two for loops, ig it should be v^2

[@AryanPatel-wb5tp]

What is run time , O(V+E) ? can someone explain line by line using the pseudocode if possible

[@ameynaik2743]

Nice video, how is this different from another video you have on top sort using dfs?

[@pankajpanwar9385]

Even tho you say that the in-degree array has to be number of nodes the current index is connected to indegree[0] = 0 Actually in code it seems like you're populating the in-degree by adding the number of nodes connected to the current index indegree[0] = 3

[@bullymaguire2335]

Dude just increase ur volume .no other complains .👍

[@akashshirale1927]

can u post videos on identifying kadane's algorithm for dynamic programming

[@WebSurfingIsMyPastime]

Great Video!

[@amanbhatia7442]

just realized you have a similar algorithm for the dfs approach as well? , But I really like this, feels intuitive

[@saralee548]

amazing.

[@ManishaSingh-yk5en]

Can we get the ppt which is being used in the video?

[@76lunagogogo]

Regarding the DAG, isn't the (3) also not he DAG as the same reason that (4) one has?

[@alifrahman7099]

Amazing

[@zappist751]

MAH MANNN

[@无名-c1f]

What drawing software to use？ The picture is very nice

[@pamp3657]

very good video

[@tarunstv796]

Will this approach also work for cyclic graphs? *When I say it will work, I mean it will let us determine whether the graph is cyclic or not, or if a DAG will provide valid ordering.

[@shreyashachoudhary480]

Awsm!

[@nitika9769]

my Saviour

[@krealle]

Thanks!

[@mnchester]

great vid

[@bxfootballphenom]

I've been running into a problem with this algorithm when there is no node 0. In this case, the inDegrees array will always have the 0th index be 0, and since there is no "0" node to add any incoming dependencies it will incorrectly add it to the queue. This also ends up breaking the rest of the algorithm since the true size of the inDegrees array is 1 less than what we were expecting. For example if our vertices are [1,2,3,4] the inDegree array at initialization will be [0,0,0,0] and will only match up to vertex 3, since at iteration it will be expecting i to start at 0. Has anyone else come across this and how have you solved this?

[@WilliamFiset-videos]

Hey Cesar, when labelling the nodes of the graph you should always label the first node as node 0, the second node as node 1, the third node as node 2 and etc... This should ensure that you always have a node 0, does this resolve your problem?

[@bxfootballphenom]

@@WilliamFiset-videos Thanks!

[@andreyvalverde4780]

hi there, quick question, based on the code, how do we make sure that we are not adding vertices that we've already visited?

[@RushOrbit]

Where did you find the intro music for your videos?

[@karankanojiya7672]

Respect++

[@enlgn7050]

Okay....Now I get it. Superman got his DAG messed up