4.2 All Pairs Shortest Path (Floyd-Warshall) - Dynamic Programming

[@mr.aravindreddy]

Sir At 6:39 I think for A^1[4,2] the value is 5 but not 8.

[@OneLordeAnimeClips]

You are correct.

[@MiEthioEntertainmentPLC]

@@OneLordeAnimeClips yep

[@MiEthioEntertainmentPLC]

Ure crct

[@shubhamchaudhari9475]

Correct

[@andrewsa7980]

Crt

[@karanpuri1617]

you're a perfect example of how a CSE Teacher should be.

[@sundaramsaroj2087]

Very true!!!!!!

[@justinjohnson7717]

Correct 😀. This is my homework. I did my homework with the help of this video. 😁

[@karanpuri1617]

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[@karanpuri1617]

@@abhaykumarkanaujia ab tujhe gadhe ko yahan bi ni samajh aaya to fir chhod hi de tu

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@@karanpuri1617 chodh bhai wo production waala hai😂

[@riley_6913]

In less than 15 minutes you managed to clearly explain something my professor couldn't explain in an entire semester. Eventhough I'm late relative to when this video was uploaded, I still wanted to take this time to thank people like you, who provide an invaluable service to us all.

[@devbhavsar7799]

I think your syllabus is shit..my college does not teach me only warshall for 6 month

[@ssshukla26]

I am just passing my algo exams because of you sir. Thank you so much...

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Dear sir, You have been an incredible help in my studies. I didn’t understand my courses very Well Because the teacher wasn’t the greatest, But Thanks to you i was able to pass all my finals! I am so grateful for these amazing video’s and i truly hope you Will continue to make such Good video’s! You are one of the best teachers when it comes to algorithms, bravo!

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ZOV

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[@tausifahmad2007]

sir i think at 6:39 for A-1[4,2] there will be 5 not 8

[@bhavikabharti66]

Yes

[@umernasir4217]

Agreed.

[@coolboy98iscool]

agreed

[@abhipatel3512]

Yes

[@someonesoumya]

yess

[@akaari3820]

Didn't understand anything in a 90 minutes lecture, immediately understood the algorithm after just 4 minutes of this video. You're legendary

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[@JoseSanchez-vv1zd]

Greetings from southern California! You make learning algorithms so much easier and interesting! Thank you for your great work, Abdul!

[@kamenpetkov192]

My Algorithms teacher was struggling big time with this one lol. And here, sir Abdul Bari explained it perfectly in 14 minutes. Great teacher!

[@josepaul2725]

Correction A1 matrix (4,2) = 5

[@thomasjaszczult1118]

Thank you. I thought I was going crazy

[@majidmohammed5412]

@@thomasjaszczult1118 same here haha

[@onionindo]

same here 'hahaha

[@tana36735]

true

[@rahulghosh4805]

Right A1 is wrong

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I shared a link of this video to my professor........and next day he thanked me.

[@solidname9085]

same with me

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Haha😂😂

[@thefahad449]

Your students are lucky to have a professor like you. I wish all my professors thought CS like you do!

[@Superalexandru2]

Thank you professor for this wonderful explanation! Your videos mean so much to students all over the world. Greetings from Politehnica University of Bucharest ! (Romania)

[@tabreazahmedzerdi9844]

this type of lectures in India for us this is really heaven sir

[@Pandreou261]

you are saving my life.Thank you brother. Brother from different mother :)

[@Joqu1nn]

This could not have been a more concise and clear lesson. Thank you sir

[@EscapedConvict2007]

The best thing happened to me today was stumbling upon this channel. I was just not getting the Floyd-Warshall explanation from wikipedia. The explanation here is crystal clear.

[@jknair0]

I wonder how this professors aren't the greatest programmers

[@ptreeful]

When I first read about this algorithm, I understood nothing. After your explanation everything is clear, I love you!

[@nickzervas4937]

When comparing the Floyd Warshall method with the Djiktra method , i think there are 3 important things you should have pointed out : 1) The Djiktra method can be achieved with less complexity , especially with sparse graphs . By using binary heap as a priority queue we achieve O(n*m*logn) and with a fibonacci heap we achieve O( (m+nlogn)*n). 2) The main advantage of this method compared to Djiktra is that it can be implemented in a graph even if we have edges of negative weights ( as long as there are no negatives circles ) . Djiktra is highly limited by that aspect . 3) The best algorithm for this method which benefits both from 1,2 is : Johnsons . It can be achieved in O( (m+nlogn)*n) even if we have negative weights ( no negative cycles )

[@aurobindamohapatra6781]

Absolutely

[@victorabhinav2652]

If there is a negative cycle ->one of the elements in the diagonal will be negative

[@abraramin3146]

thanks bro you cleared my confusion.i had this doubt that what is the benefit of using this algorithm if the time complexity is not improving....the sir told in the begining that we can use dijktras algorithm but we will get O(n3) time complexity and at the end calculated the time complexity of this algorithm as n3 . so it didn't make any sense.

[@JohnCena12355]

Thank you so much! the instances of matrices is a unique way of teaching this and made me understand instantly! Much better than starting with the algorithm and following from there. Bravo!

[@qiyueliang6089]

Very good logic, very clear explanation, very nice example, makes me understand the idea immediately after watching the first half of the video without having to check other information. You're one of the best lecturers I've ever seen!

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[@heyyou8771]

in video - at 8:36 AND 8:38 they changed the value of A'[4][2]=5 , don't get confuse...

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👍

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my main goal today was to understand this algorithm and it's crazy how you achieved to explain this in 15 min something that no uni teacher over here could do. crazy sir thank you

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Awesome teaching style. Your teaching style have patience, which is most important for good teaching.

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I am an undergrad student at IITD I was really having a tough time understanding this but this video made it so easy.....

[@harsha1786]

Very good sir .While my sir explaining I was confused with the formula and made it difficult but u made it simple now ,even I understand formula simply

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[@kunalchoudhary7477]

correction A^1[4,2]=5.

[@eurus7509]

I was looking for this comment.I thought i made a mistake taking 5...ty

[@mitali7959]

@@eurus7509 same here

[@srinjoydas1314]

eggzacly , thanks

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I literally spent 1 hour right before my exam looking at your videos and understood everything I needed to know highly recommend the dijkstra prim kruskal floyd lessons were amazing.

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tomorrow exam.. today binging your lectures ..understanding each and every concept which would go on top of my head in classes ..hope i do well tomorrow

[@tanujgehlot2600]

6:40,Correction A1 matrix (4,2) = 5

[@nusratfans39]

he wasted my time for this mistake and even confused me

[@_outcyrptolist]

@@nusratfans39 always check for comments when u face such issue

[@HARIHaran-ks7wp]

@@_outcyrptolist true dat

[@lucam9806]

Your explanations are the best. Every week I have to do exercises for the Algorithms and data structures lecture, your explanations help me so much. I really like how you showed the example first, then deduced the formula. It's a lot easier to understand this way. Greetings and big thank you from Germany.

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Nice to see people viewing from outside India as well. Gut!

[@mochoye]

I guess there is a small mistake at A1[4,2] will be 5 as A0[4,1]=2 and A0[1,2]=3. So 3+2=5.... Correct me if I am wrong 🙂

[@anandiyer5361]

you saved me from ruins...sir! Thanks so much...I was feeling totally down, having listened to my professor and unable to understand anything.

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Thanks Abdul! See you at England v Holland.

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Hi there Gregory how are you

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[@malteiwa]

thank you very much, this was much better explained than from my own professor. Greetings from Berlin, Germany

[@ashishdwivedi5190]

@13:55 isn't the time complexity again n^3 which we were trying to avoid initially??

[@techwithwhiteboard3483]

yes it is i think the constant term in this asymptotic n3 is lower than simply using djikstra several times

[@kritikhetan]

@@techwithwhiteboard3483 even my point is also the same...time complexity as of using dijkstra also n times .@abdul Bari sir plz solve this doubt..thanks for wonderful explanation

[@abdul_bari]

We were not trying to reduce time. We just saw a different approach

[@kritikhetan]

@@abdul_bari thanks a lot sir..was stuck in this concept..ur vedios have cleared lot of my doubts in algorithm

[@WeiShiunHUNG]

Thanks from Taiwan. Have learned really much from your videos.

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yahahaha my friends were telling me I would fail this subject because of those algorithms because I didn't attend the classes but thank god internet exist I will pass like a boss

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Thank you so much for making these videos! It's crazy how much better I understand Floyd-Warshall now

[@ronitkumar1838]

finally i understand this algo...thank you so much

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I gave up the lecture videos from my professors and watched yours. Super helpful.

[@Geethanjalireddyy]

Sir, There is a mistake in finding A1 A1=0 3 α 7 8 0 2 15 5 8 0 1 2 5 α 0 Can u check it sir....

[@r0wdybandit015]

7:27 bars btw this is the best video on Floyd's Algorithm on youtube. Thank you so much sir. I salute you.

[@siddharthmanumusic]

Thank you for the beautiful explanation. One observation: Isn't the time complexity of Dijkstra to find all pairs shortest path same as that of Floyd Warshall? I think the only advantage of FW is that it can also find it for negative weights plus it's easier to implement - no priority queue or extra space complexity.

[@madhurya6417]

Sir... U are amazing.. Actually my teacher is following what ur saying..

[@shiwanggupta8608]

Dijkstra takes O(ElogV). So, if we calculate using Dijkstra it would be O(n^3*logn)

[@shiwanggupta8608]

For a dense graph E=O(V^2), So, worst case time complexity will be O(ElogV*V)=O(EVlogV)=O(n^3*logn)..

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Thankyou from NIT Warangal

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Sir you provide better lessons for free than most of my "Highly educated" professors of my college(fees was not cheap)

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Great experience sir. Plz upload more videos

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his videos have been saving me so much time and effort. wish all professors could be as good as him!! many thanks

[@dushyantkaushik335]

A1[4,2] should be equal to 5 instead of 8

[@aadityapritam4709]

Ya i thought there should be 5 instead of 8.. But thats ok.. I understand the concept

[@Ankit-mq6em]

@@abdul_bari woooowww

[@shreedharsharma6663]

Big fan of your teaching style sir... Very unique and diligent ❤️🙏🏻

[@JaspreetSingh-zp2nm]

Usually I don’t like India teaching videos but this tutorial is very clearly presented

[@sanjeebbaitha96]

till 8:31 there was a mistake 4,2=8 instead of 8.....but corrected nice video

[@vivekbkumbar]

Sanjeeb Baitha yeah i noticed also

[@lukapavlovic9873]

That's a real understandable !! raw model how every teacher should be teaching.

[@adithyas6863]

Our teacher told this is the formula, just memorize it no other go ಠ︵ಠ

[@VikasSharma-cv1su]

excellent Explanation , In a single go i understood i didn't need to watch this video second time. Thanks Bari

[@lifeexplorer2965]

If Complexity is O(n^3) using DP also ,then we could have used Dijkstra's also then what is the benefit of using DP

[@yashtailor1543]

There are multiples ways to Solve every problem.

[@dheerjain2884]

Dijkstra wont work for negative edges

[@nishtha27]

Probably the best explanation of Floyd-Warshall algo, thank you!

[@AMITKUMAR-te9bn]

What About Complexity? Is it still N^3.

[@abhishekmazumdar2072]

Time O(n3) Space O(n2)

[@camilaperez7580]

Thank you so much. I understood more in the first 4-minutes of this video than in any of my network flow classes.

[@markos9712]

you are my god, my lovely indian sir god