I don't know if you know this, and this is 4 years late, but this is one of the cleanest, easiest to understand video's (conceptually-wise) for Dijkstra's. I've seen several, but this! This is the best one. :)
This is literally one of the cleanest, simplest, no-nonsense beautiful explanations of an algorithm I have ever watched on TH-cam. Amazing. To-the-point. Crisp. And so easy to understand and digest. THANK YOU.
Seriously, I've been looking at so many pseudocodes and incomprehensible python scripts without any clear explanation on how the algorithm actually works. I salute you. This has helped me so much. I can't thank you enough.
You sir are BY FAR the BEST teacher of algorithms on TH-cam or anywhere else I've seen algorithm lectures. THANK YOU FOR POSTING THIS! With your well-paced, methodical style you could probably teach anything!!!!
Hi FTP My scenario is for a non-directed graph (you can go backwards and forwards on any edge), so all the nodes can indeed be reached. However, for a directed graph, some nodes may be unreachable from the given start, as you have intimated. Dijkstra's algorithm finds the shortest paths only to the nodes that can be reached from the starting node. (if there is no path to a node from the start, it's irrelevant). The loop will end when all 'reachable' vertices have been visited. By the way, Dijkstra's algorithm doesn't work if the graph edges have negative weights.
i used to think this "Dijkstra’s Shortest Path Algorithm" is not for me to understand :) , now i can do it even getting from sleep after watching this video , thanks a ton !!!
I must commend the quality and clarity of this video: it is by far the best video I've seen on TH-cam to date on the subject of explaining Dijkstra's Algorithm. There are so many other videos that do not deal with the problem of keep a record of the shortest route sufficiently systematically enough, in my opinion. This video is systematic, showing the use of a table to perform the algorithm very clearly. Instruction of this level is not accidental; my congratulations to those involved in its production and execution. You have done the domain of Computer Science the world of good. Keep up the great work!
Appreciate this video. Watched a number of others about Dijkstra's Algorithm and couldn't understand HOW and at what stage another path is evaluated. It wasn't until I saw the graph and how we can track the changes that it somehow brought the entire algorithm into crystal clear focus. Thanks!
I'm a programming lover man who have no computer science degree. I have seen many videos but this is the best and easiest way to explain the algo... Thanks a lot.. want more
Really appreciate this video. As a network engineer, i have read many book about how SPF works but this one is the best. And i can also develop the code based on this video. One thing I was stuck for a while is when having the directed graph (shorted path), it is a bit tricky to print all the shortest path considering ecmp case.
This is very enlightening. I’ve come up with a similar algorithm myself that uses a simple width-first or depth-first search, but I’ve never thought of that we should first calculated the vertex with the least known distance! Thanks for sharing it.
The fact that this explanation of Dijkstra's is way more easily understandable and to-the-point than the one Computerphile has is astounding. Slides ftw
The best video on shortest path algorithm on TH-cam. Some of other videos that comes at the top of the search result are crap. People have unnecessarily complicated the explanation.
Such a clear and coherent explanation. Watched the Craig n Dave video on this previously but this is such a clearer explanation. Understand this now cheers!
We are learning about Dijkstra's Shortest Path in my Data Communications course and this video explains the algorithm much more clearly than my professor had attempted to explain in our lecture video / notes. Thank you very much, in just 10 minutes I was able to understand something I was spending 30-60 minutes on. Well done!! :)
Fantastic explanation. Indeed, it's the best, clearest, simplest, and most useful resource by far that I've found after hours of searching. Thanks for making it!
It's the clearest explaination for Dijkstra I have seen before. Here is my test code for java according to your lecture. Just a litte complicated to build the model which you present in video. import java.util.ArrayList; import java.util.List; public class Dijkstra { public static void main(String[] args){ List vertexList = buildVertexs(); // a weight or distance matrix to present vertex to other vertex if they are adjacent, // else if they are not adjacent mark as -1 int[][] matrix = new int[vertexList.size()][vertexList.size()]; matrix[0]= new int[]{0, 6, -1, 1, -1};// a-a->0,a-b->6,a-c->-1(no neighbor relation），a-d->1, a-e->-1 matrix[1]= new int[]{6,0,5,2,2};//b-a->6,b-b->0,b-c->5，b-d->2, b-e->2 matrix[2]= new int[]{-1,5,0,-1,5};// c-a->-1(no neighbor relation）,c-b->5,c-c->0，c-d->-1(no neighbor relation）,c-e->2 matrix[3]= new int[]{1,2,-1,0,1};// d-a->1,d-b->2,d-c->-1(no neighbor relation），d-d->0,d-e->1 matrix[4]= new int[]{-1,2,5,1,0};// e-a->-1(no neighbor relation）,e-b->2,e-c->5，e-d->1,e-e->0 List result =findDijkstra(matrix,vertexList); for(Vertex v: result){ System.out.println("A to "+v.getName()+" shortest path is "+v.getShortPath()); } } public static List findDijkstra(int[][] weightMatrix, List vertexList){ List visitStatus = new ArrayList(); while(visitStatus.size()!Vertex.isVisited())).min((Vertex::compareTo)).get(); int index = vertexList.indexOf(current); for(int i=0; i
I absolutely, unquestionably agree that rigorous math definition is important and necessary for this kind of stuff. That said, why do most math/cs book authors are so TERRIBLE at teaching? To the point that you have to spend gold on a number of expensive books in a desperate attempt to learn one thing well. I mean, feel free to lay out the rigorous math stuff, I know that's important, but please please PLEASE also give us a decent, understandable, not-vaguely-abstract translation of that stuff. Awesome video by the way! Thanks so much.
Delighted to help. Remember, Dijkstra's is a greedy algorithm. It always selects the nearest node next, on the assumption that this will ultimately lead to the shortest overall path. It's common for an examiner to ask you to compare Dijkstra's algorithm with the A* algorithm . Good luck :)KD
@@ComputerScienceLessons Wow man, my teacher did asked the question to compare Dijkstra's algorithm with the A* algorithm and Bellman-Ford. You are a god. Btw love your new series and waiting for more
Slight correction: this algorithm is not greedy! Yes, it jumps to the local optimum at every step but it also goes back and updates any decision that it has already made in previous iterations. A truly greedy algorithm would just run towards the "closest" neighbour that he hasn't already visited, most probably finding himself forced to run down an stupidly costly edge. Other than that, wonderful video!
This is by far the best video I've seen on this subject it made implementation very easy and the explanation is the best I've ever seen so thank you very much!
I don't know if you know this, and this is 4 years late, but this is one of the cleanest, easiest to understand video's (conceptually-wise) for Dijkstra's.
I've seen several, but this! This is the best one. :)
Great to hear! :)KD
@@ComputerScienceLessons lol, but i'm listening even now, best explanation. Keep it up
I agree fully. Best !
@@ComputerScienceLessons He's right! It was veryyy easy to understand. Thank you
stunning, clear explanation. Thank you so much!!!
FINALLY SOME CLEAR STUFF. almost crying
jaja...you made my day
Me too!!
said what i wanna say
HAHAHAHAHA
mood
!!!finally a good and simple explanation
oh tears of joy...
may the gods bless you with bugless codes
"May the gods bless you with bug-less codes."
I'm going to use that a lot.
haha epic comment bro
This is literally one of the cleanest, simplest, no-nonsense beautiful explanations of an algorithm I have ever watched on TH-cam. Amazing. To-the-point. Crisp. And so easy to understand and digest. THANK YOU.
This has to be the best explanation of Dijkstra's Shortest Path algorithm... Thanks a lot!
The best video on the internet explaining the Dijkstra’s algorithm, thanks a lot sir.
You're welcome :)KD
Seriously, I've been looking at so many pseudocodes and incomprehensible python scripts without any clear explanation on how the algorithm actually works. I salute you. This has helped me so much. I can't thank you enough.
Yo are most welcome :)KD
You sir are BY FAR the BEST teacher of algorithms on TH-cam or anywhere else I've seen algorithm lectures. THANK YOU FOR POSTING THIS! With your well-paced, methodical style you could probably teach anything!!!!
Hi FTP
My scenario is for a non-directed graph (you can go backwards and forwards on any edge), so all the nodes can indeed be reached. However, for a directed graph, some nodes may be unreachable from the given start, as you have intimated. Dijkstra's algorithm finds the shortest paths only to the nodes that can be reached from the starting node. (if there is no path to a node from the start, it's irrelevant). The loop will end when all 'reachable' vertices have been visited. By the way, Dijkstra's algorithm doesn't work if the graph edges have negative weights.
I haven't found a better tutorial than this for understanding and computing distances using Dijkstra's algorithm. Thank you so much.
You are most welcome :)KD
Extremely clear, extremely well put together visually. Well done, and thank you.
I really appreciate your comment. Thanks.
extremely
Even 6 years later, this is still the best explanation ever
I can't believe how well done this video was made. I appreciate your hard work at a visual representation of this algorithm.
I signed in just to like this video.
and to comment apparently
U r loyal
This is by far the best video I've seen on this algorithm. It is clear and doesn't skip any steps.
Thank you :)KD
i used to think this "Dijkstra’s Shortest Path Algorithm" is not for me to understand :) , now i can do it even getting from sleep after watching this video , thanks a ton !!!
I must commend the quality and clarity of this video: it is by far the best video I've seen on TH-cam to date on the subject of explaining Dijkstra's Algorithm. There are so many other videos that do not deal with the problem of keep a record of the shortest route sufficiently systematically enough, in my opinion. This video is systematic, showing the use of a table to perform the algorithm very clearly. Instruction of this level is not accidental; my congratulations to those involved in its production and execution. You have done the domain of Computer Science the world of good. Keep up the great work!
Thanks for the great comment Mike.
man this Dijkstra guy deserved a nobel prize for it
He was a clever chap! :)KD
I wish I could upvote this more than once. It is honestly a brilliant, clear, and concise explanation
You are very kind. Thanks. :) KD
@@ComputerScienceLessons But really it's awesome video.. the best info in the least possible time.. Thank you so much from India 🥰
Appreciate this video. Watched a number of others about Dijkstra's Algorithm and couldn't understand HOW and at what stage another path is evaluated. It wasn't until I saw the graph and how we can track the changes that it somehow brought the entire algorithm into crystal clear focus. Thanks!
You are most welcome :)KD
Lovely, this has been the clearest explanation I've seen so far for Dijkstra's algo. Seriously, thank you so much!
Thanks for saying so. You're most welcome :)KD
We won't be visiting A, again.
Me: CRIES LOUDLY
A was no fun. :) KD
🦍🦍😂😂
Wiz Khalifa's "See You Again" Plays in The Background
i laughed hard reading this
You’re hilarious
An entire computer science degree courses embedded in this amazing channel. Thank you. Not all heroes wear a cap.
After spending lots of time on other videos and stuff finally, I have understood "Dijkstra’s" Thanks to this LEGEND.
You are most welcome :)KD
The VERY clearest and well-paced explanation by far! Thanks!
You are too kind :)KD
Absolutely the best explanation. Cleared up any and all lingering questions in my mind.
If you can't explain it simply, you don't understand it well enough. Beautifully done. Thank you!
I'm a programming lover man who have no computer science degree. I have seen many videos but this is the best and easiest way to explain the algo... Thanks a lot.. want more
Thanks for the comment. Plenty more on the way.
I've watched a lot of videos on this algorithm and let me tell you if you're watching this you are at the right place..
and thank you so much Sir!
You are very kind. Thank you :)KD
Thanks for your extraordinary explanation. This is literally one of the simplest explanations of an algorithm I have ever watched on TH-cam.
Thank you. You are very welcome:)KD
Thank you for including the psuedo-code at the end. Really helped me get an idea of how I should structure my own code!
Glad to help :)KD
I have never seen a video with such clear and step-by-step explanations. Good job here!
I appreciate the comment. Thanks. :) KD
Finally a video explaining IT stuff without nearly not understandable indian accent!
Exactly! ... :D
grow up mate
They are clever though so you can't hate em.
better to eat curry than insects and dogs
Oh look kid. That thing under this guy's butt is what fire looks like.
BEST explanation of Dijkstra's algorithm EVER!
When I was doing MCA noone explain us in such a simple way...... Now it's so easy after this video... thanks for your kind information....
You are very welcome. It's a tricky topic. :)KD
I'm watching a bunch of your videos to review for my Algorithms exam. Thanks a bunch for making these!
Thanks for the comment. It's good to hear you're finding them useful. :)
Really appreciate this video. As a network engineer, i have read many book about how SPF works but this one is the best. And i can also develop the code based on this video. One thing I was stuck for a while is when having the directed graph (shorted path), it is a bit tricky to print all the shortest path considering ecmp case.
This is very enlightening. I’ve come up with a similar algorithm myself that uses a simple width-first or depth-first search, but I’ve never thought of that we should first calculated the vertex with the least known distance! Thanks for sharing it.
Don't thank me, thank this guy :)KD
en.wikipedia.org/wiki/Edsger_W._Dijkstra
Fantastically clear and concise. Makes my revision an absolute dream, I can’t thank you enough. 10/10
Thank you. Delighted to help :)KD
It's really interesting, how sometimes one thorough example can clear up everything.
This 10mins video >>> 45mins video from my lecturer. LEGEND🙏
The fact that this explanation of Dijkstra's is way more easily understandable and to-the-point than the one Computerphile has is astounding. Slides ftw
You're too kind. Thanks you. :)KD
@@ComputerScienceLessons I thank you, recently passed my discrete maths exam :)
This is the single best and most simple explanation of Dijkstra's algorithm. It saved me multiple times.
Thank you so much.
Thank you for the kind comment
@@ComputerScienceLessons No need!
The best video on shortest path algorithm on TH-cam. Some of other videos that comes at the top of the search result are crap. People have unnecessarily complicated the explanation.
Thanks for the comment. Much appreciated. :)
Such a clear and coherent explanation. Watched the Craig n Dave video on this previously but this is such a clearer explanation. Understand this now cheers!
Glad you found it useful. There is nevertheless some good stuff on Craig n Dave's channel :)KD
Perfect video! Clear examples, understandable English and ... no profanity.
Glad you liked it. Thanks for the comment. :) KD
This video is your shortest path to learn Dijkstra Algorithm.
🤡 :)KD
This is the best video on Dijstra's Shortest path algorithm I have viewed on TH-cam. Kudos!
After watching about 5 videos on this algorithm, yours has made it crystal clear. Thank you.
You're very welcome. :)KD
@@ComputerScienceLessons Your A* explanation is also the best I found
Thank you!
This is the single best video explaining the algorithm on TH-cam.
This video is a definition of precise and concise explanation. Thank you very much.
Crying in disbelief 😭😭. Finally some clear explanation. Thank youuuuu
You are very welcome. Glad to help. :) KD
Great explanation! Finally, I understood it. The table really helps to not get lost. Thank you so much!
I had to watch this video two times in order to grasp the concept. Thank you!!
You are very welcome. I get my students to check their understanding by working through the algorithm with a different graph. :)KD
The clearest, and most succinct, explanation of Dijkstra's algo I've seen. Thanks!
This explanation is by far the Best I've seen.. This is crystal clear , thank you very much!
You are very welcome, and thank you :)KD
This is the fourth video I had to watch. Only one that explains clearly, thanks.
Thanks for actually including the way to find the shortest path between the start node and a certain node, alot of tutorials leave that out
You're welcome :)KD
This is the best explanation of Dijkstra's algorithm I have seen!! I especially like the last summary part.
Thank you. Glad to help :)KD
We are learning about Dijkstra's Shortest Path in my Data Communications course and this video explains the algorithm much more clearly than my professor had attempted to explain in our lecture video / notes. Thank you very much, in just 10 minutes I was able to understand something I was spending 30-60 minutes on. Well done!! :)
You know this is the best illustration and guideline for implementing it on youtube.
Thanks :) KD
This is the best explanation for Dijkstra's shortest path. Thank you so much
You are very welcome :)KD
You explained this so incredibly clearly! It's really not that hard at all! Thank you so much!
two hours of a boring lecture vs 10mins cool explanation. thanks mate
You're very welcome :)KD
Thank you very much! I have been trying understand this algorithm for 5 hours and I finally got it now "thanks to you"!
You're most welcome :)KD
Fantastic explanation. Indeed, it's the best, clearest, simplest, and most useful resource by far that I've found after hours of searching. Thanks for making it!
Thank you - and you are most welcome :)KD
Wonderfully explained. The best video i have come across so far on Djikstra's Algorithm.
I am just captivated by the appealing spoken English
Thank you :)KD
By far the best video for explaining this algorithm! Perfect.
It's the clearest explaination for Dijkstra I have seen before. Here is my test code for java according to your lecture. Just a litte complicated to build the model which you present in video.
import java.util.ArrayList;
import java.util.List;
public class Dijkstra {
public static void main(String[] args){
List vertexList = buildVertexs();
// a weight or distance matrix to present vertex to other vertex if they are adjacent,
// else if they are not adjacent mark as -1
int[][] matrix = new int[vertexList.size()][vertexList.size()];
matrix[0]= new int[]{0, 6, -1, 1, -1};// a-a->0,a-b->6,a-c->-1(no neighbor relation），a-d->1, a-e->-1
matrix[1]= new int[]{6,0,5,2,2};//b-a->6,b-b->0,b-c->5，b-d->2, b-e->2
matrix[2]= new int[]{-1,5,0,-1,5};// c-a->-1(no neighbor relation）,c-b->5,c-c->0，c-d->-1(no neighbor relation）,c-e->2
matrix[3]= new int[]{1,2,-1,0,1};// d-a->1,d-b->2,d-c->-1(no neighbor relation），d-d->0,d-e->1
matrix[4]= new int[]{-1,2,5,1,0};// e-a->-1(no neighbor relation）,e-b->2,e-c->5，e-d->1,e-e->0
List result =findDijkstra(matrix,vertexList);
for(Vertex v: result){
System.out.println("A to "+v.getName()+" shortest path is "+v.getShortPath());
}
}
public static List findDijkstra(int[][] weightMatrix, List vertexList){
List visitStatus = new ArrayList();
while(visitStatus.size()!Vertex.isVisited())).min((Vertex::compareTo)).get();
int index = vertexList.indexOf(current);
for(int i=0; i
Glad to help
Excellent work, Clarity, and explanation at all stages. Thanks, keep up the good work
The way you explained the algorithm was just great, thanks a lot for making this video!
Tnx for the feedback :)
Computer Science can you explain bellman ford too
When he said "We won't be visiting A again", I felt vaguely threatened, not gonna lie.
Sorry about that. The fact that the nodes spell out DEAD was a pure accident too! :)KD
😂
I couldn’t have asked for a clearer video, thank you sir.
You're most welcome :)KD
Thanks to your clear explanations, I won't be visiting this video again.
Maybe just once more before the finals.
I hope you will be visiting 'A' :)KD
I will recommend a Nobel prize for you for this explanation
I absolutely, unquestionably agree that rigorous math definition is important and necessary for this kind of stuff. That said, why do most math/cs book authors are so TERRIBLE at teaching? To the point that you have to spend gold on a number of expensive books in a desperate attempt to learn one thing well. I mean, feel free to lay out the rigorous math stuff, I know that's important, but please please PLEASE also give us a decent, understandable, not-vaguely-abstract translation of that stuff.
Awesome video by the way! Thanks so much.
Hi from Argentina. After watching 4 other videos I can say this is the best explained solution steps I've found so far. Thanks!!
Tnx
Le me cry of joy because I find this absolute gem to prepare for the final.
Delighted to help. Remember, Dijkstra's is a greedy algorithm. It always selects the nearest node next, on the assumption that this will ultimately lead to the shortest overall path. It's common for an examiner to ask you to compare Dijkstra's algorithm with the A* algorithm . Good luck :)KD
@@ComputerScienceLessons Wow man, my teacher did asked the question to compare Dijkstra's algorithm with the A* algorithm and Bellman-Ford. You are a god. Btw love your new series and waiting for more
This is a great video. You have provided a very simple but clear explanation.
you are such great story teller, to learn algorithms as a story is fantastic, please continue ...
Thanks for the lovely comment. I working on some new videos at the moment.
@@ComputerScienceLessons Go on boss
Tomorrow I have my exams on this topic.. This is the best video about djkstras algorithm on whole internet
Slight correction: this algorithm is not greedy! Yes, it jumps to the local optimum at every step but it also goes back and updates any decision that it has already made in previous iterations. A truly greedy algorithm would just run towards the "closest" neighbour that he hasn't already visited, most probably finding himself forced to run down an stupidly costly edge.
Other than that, wonderful video!
Best video on Dijkstra I've seen so far. Thanks for doing it with so much clarity.
Omg.. out of like 10 dijkstra vids i attempted to eatch this is the best
You are the KING THE SAVIOUR OF ALL CS MAJORS THANK GOD YOU MADE THIS VIDEO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
You are very kind, and most welcome :)KD
I FINALLY UNDERSTAND THANK YOU SO MUCH!!!!
This was the most concise and easy to follow video I've managed to find on this algorithm
You are most welcome. I usually ask my students to check their understanding by working through it with a different graph. :)KD
I had closed the tab after watching video. Just remembered and came back to give a like. Great video
Thanks for coming back. Much appreciated. :)KD
This video is a game changer. Understood it in one shot. Brilliant!
Thank you :)KD
Finally, an example that makes sense, wonderful job!
Glad to help :)KD
Thanks James May. This was a great episode of Top Gear
This is by far the best video I've seen on this subject it made implementation very easy and the explanation is the best I've ever seen so thank you very much!
u r king of simple and clear explanation
Thank you :)KD
Thanks for this! As others have said, this is one of the clearest explanations on youtube!
At 4:01 it struck me how this is going to work and how clever it is. Really neat!
Agreed. You have to admire Edsgar Dijkstra for dreaming it up.
Thank you, sir. Thank you. Finally someone that can make it clear for a min span tree
Glad to be of service. Thanks for the kind comment. :)KD
So easy to follow. Best video I’ve seen on this algorithm
Damn such a nice tutorial. Also you're making stuffs for VB, you're like the dream channel I've been searching.
Wow it's an honor to be learning this from Computer Science itself
You've just earned yourself a new subscription champ! Great video! I love it!
Thank you and you are most welcome :)