Graph Algorithms for Technical Interviews - Full Course
ฝัง
- เผยแพร่เมื่อ 22 พ.ค. 2024
- Learn how to implement graph algorithms and how to use them to solve coding challenges.
✏️ This course was developed by Alvin Zablan from Structy. Check out Alvin's channel: / alvintheprogrammer
🔗 Learn data structures and algorithms: structy.net/
⭐️ Course Contents ⭐️
⌨️ (0:00:00) course introduction
⌨️ (0:02:23) graph basics
⌨️ (0:07:10) depth first and breadth first traversal
⌨️ (0:29:13) has path - structy.net/problems/has-path
⌨️ (0:42:11) undirected path - structy.net/problems/undirect...
⌨️ (1:00:44) connected components count - structy.net/problems/connecte...
⌨️ (1:13:29) largest component - structy.net/problems/largest-...
⌨️ (1:24:03) shortest path - structy.net/problems/shortest...
⌨️ (1:39:36) island count - structy.net/problems/island-c...
⌨️ (1:58:52) minimum island - structy.net/problems/minimum-...
⌨️ (2:12:05) outro
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This guy is phenomenal. His course on dynamic programming was exceptionally well done as well.
A little old comment, but exactly my thought, I just went through his dynamic programming course and completely agree
@@mauricemarin5810 same here
Hi, @Chris can you add a link to the dynamic programing course. Thanks
@@elad7264 th-cam.com/video/oBt53YbR9Kk/w-d-xo.html
Agreed
after that course, I am so confident on DP.
Einstein once said "If you are able to explain it to a 5 year old, you understand it yourself". Alvin, you are one of a kind!
Richard Fynman said that.
@@syedtalha1264 I also said that, hey!
Another immortal quote: ‘I stand on the shoulders of giants’ was attributed to Isaac Newton, as it turns out he wasn’t the one who coined it.
I can verify that I’m 5 and I do understand this thanks to this video.
Leetcode - O(n^2) brute force.
Algoexpert - O(n) linear
Alvin / Structy - log(n)
😂😂 True
Man! you have my respect. This was the best course for getting started with graph problems I have ever seen. Thank You so much.
This is phenomenal! I was finding Graph problems so difficult before watching this video, and now they seem fairly easy after watching the entire video! Thanks a ton!
I'd always been scared of learning graphs, even though I wanted to... but this course took my fear away 😎👍🏻 excelente course, as always!
This course is hands-down, unequivocally fantastic!!! Best useful course I've seen about graphs. It ties together the algorithms with concrete use cases which just clicked. Thank you for the fantastic job!!!!
“Later on in the tutorial we’ll go over examples of when u might use one over the other”
What a breath of fresh air 🙏🏼
This is the only course I’ve found that has successfully got the concept of graphs through my thick skull, it’s been a subject that’s been so hard for me to learn. Thank you for making this!!
This was amazing. I've watched a bunch of these types of videos over the years and this is the only one that actually made it look easy. I can actually say I understand this now. Thank you.
I'm a mid/senior level webdev and I just come back to Alvin's videos when preparing for interview everytime. its so simple and help me rebrush all of them without much hassle. very good work
you probably use parent_id = .. db.Column in your projects, don't you xDDD
@@ordinaryggew.
@@ordinarygg Don't get it.
I chose this video after I got an invitation for an online test from a well-known company. This was my only chance since I have never studied algorithm oriented programming.
I was given a graph problem and handled it correctly with a minor deficiency in efficiency :) Thanks a lot!
Was looking for something like this and can't beleive you just uploaded it!
Me too
Before watching this course, I dreaded DFS BFS problems. I always used to somehow understand the logic just before the interview and then forget everything. But now, I understand the logic, visualization and how to appraoch it. Thank you so much Alvin and FCC for this. I am definitely going to watch other interview videos. 👍
This was probably the most useful tutorial I've seen on YT. Great work!
Thank you for making graphs so easy for me! Appreciate your patience to make these videos and share
This course is exceptionally well done. Completely understood the theory and implementation behind them damned graphs.
Huge fan of these courses, he's a great teacher and breaks down these problems to be far less intimidating
You're doing an amazing job Alvin👍I'm always on lookout for your contents. Thank you!
OMG this video is an absolute gem! I used to be baffled by the island problem and just simply memorizing the solution on leetcode, but after following along for two hours, I can confidently code up the solution all by my self! Thank you so much you are a fantastic teacher.
Thanks Alwin for this great tutorial. I had been trying to understand and get an answer to a similar set of problems for a very long time. You made my day, ...probably my life!
Thanks for the video. To be honest, this is one of the best graph tutorials I have ever witnessed. My core concepts and understanding towards this Data Structure has improved and I really appreciate the efforts you have put in to make this video.🙏
Thank you Alvin, loved the DP course and this one as well
The course on DP was a winner. Course on Graph algo is another winner. Hope to learn a lot more from you.
you are another winner for appreciating him :)
@@keerthi1070 you are another winner for appreciating another winner
@@ziggystardust3763 you are a winner for appreciating a winner appreciating a winner
@@Tetrax this recursive call stack gotta stop somewhere XD
@@ldar6472 let’s assume we’re on an alternate universe where leetcode doesn’t have a time limit
I am actually studying C but I have found this video tremendeously helpfull in explaining how graphs are traversed and how not to use return in a bad way when you want to actually make use of recursion to backpedal from dead ends in situations where you don't find your base case.
thank you again. subscribed!
I never comment on TH-cam, but I love the way Alvin explains concepts. Thanks a lot for your work!
This guy literally changed the way I look at dynamic programming.
Thank you Alvin! Your explanation is GOLD!!! It's such a phenomenal tutorial that I find myself learning so much more efficiently!
Never looked graph so easy to me before I watched this one, thanks! 😊
Definitely was looking for this! Thanks! ❤️
Honestly one of the best tutorials ive come across in my 2 years of coding. Good work Alvin
This is really really a complete tutorial for “Graph based Problems” both in terms of coding Problems, interview preperation including MAANG and even for a new bie.
Preprocessing the input by storing edges in hashmap: this line took all my fears of not even trying to attempt graph problems to making me feel I could do any graph problems. Thanks for this video ❤️
This was not for coding interviews but a good start for beginners who are into graphs with perfect visualization
めちゃくちゃ分かりやすかった!!
Alvinさんありがとう!!
My guy, I don't know how to thank you. You have a marvelous way of teaching. This has really helped me a lot
All of Alvin's content is amazing! I signed up for Structy after doing this course and the course on trees, and love it!
easily the best teacher of algorithms I've ever seen. Alvin spends time going over theory, Big O notation, and common errors. As someone that's never studied algorithms and data structures, all the videos he has done have helped drastically
Your voice is so soothing too! Amazing video, i've always had a bit of a block when it comes to these graph algorithms but your approach/explanations finally helped me grasp them!!
Thank you so much. This is the only video on TH-cam which addresses the graph algorithms the way they should be addressed - graphical visualization, pseudocode and actual problem solving.
How this person managed to explainamy concepts perfectly is superb... We really need people like this guy in the teaching field... I downloaded the video and I ve not regretted at all
Me too I just realized Breathe First Traverse is Fibonacci
The best beginner graph tutorial.
I always come back to this to refresh myself on graphs.
This is amazing. I found it really easy to understand the graph algorithms after referring to this video. Great job, Alvin :)
Small correction in the solution described for checking if a source and destination have a path in an undirected graph. (line no. 8)
The logic of traversing the neighbors and adding the source node to the visited list has to be part of the condition that validates whether ta node is visited or not.
if !(visited.has(src)) {
// add the src to the visitors list
// recursively traverse through the src neighbors
}
Just finished the Dynamic Programming from Alvin and now back at the Graph algorithm.
Wow amazing how you made me understand graphs and I have extreme comfortability with the recursive approach and queue method. Always struggled understanding these implementations in python but as a web dev it made a lot more sense in JS. Thank you for taking the time to make this video!
watched your lecture on Dynamic Programming and now I am here. You are such a phenomenal teacher, thanks a ton for making these tutorials!
Please @rahul what's the DP link
Sooper excited for this!! Thanks you! Your DP course is excellent!
Have yet to work on this but want to express my gratitude and wish you greatness in all aspects of your life!
This is a great intro to basic graph problems - however we may need a part two to cover more advanced topics such as Union Find, Minimum Spanning Trees, Dijkstras & bellman ford, topological sort, etc.
Sure we totally need. Code interview for wannabe juniors requires some of advanced topics
Guaranteed you won't actually need any of that when actually building something in the real world.
Changing lives, one algorithm at a time. Great work Alvin!
Awesome work! You inspired me to start my coding channel!
By far the best video that I have ever seen on this topic, thank you for all the effort you put into this Alvin!
This was an elite video. I did the last two questions and did not understand how to approach it or understood what the right answer for those questions. Watch the 2+ hours of video as well as coding it up myself, and everything makes sense. EVERYTHING. I am now able to do one of the toughest topics that I was having trouble with. So BIG Thank You for that.
P.S. For the last 2 questions, you don't need the visited set, you can flip the land to water or another value altogether. Avoiding the cyclic infinite loop.
Wow!, Your DP course was phenomenal, now you came up with Graph theory too, Thank you
Glad to hear you found value in my content! More coming soon.
@@AlvintheProgrammer what next ?
@@AlvintheProgrammer this is really true! you are the best!
@@vinayaktyagi8773 Likely trees or linked lists next. You can check out my platform, Structy (link in the video description), if you want to check it out early before it premiers on free code camp.
Finished my very first fCC course. The pedagogy is excellent, Alvin is a great teacher
Your explanation is ideal. Voice and the way you expalin does not make a listener tired. This is just amazing. Please continue doing your job. It is amazing
I thought I'd seen the all the greatest of online coding instructors, and then I found Alvin... Seriously these explanations are paced exactly perfectly and ultra clear
So logical and calm and fantastic explanation. This is just unbeliveble :) How you can explain this stuff so easily. You are the legend
I learned more from this tutorial then all other tutorials that I watched combined. Great videos man!
Thank you so much, Alvin, I have always been intimidated by graphs. This is the best course you will ever stumble across on graphs.
this was such a great course, literally understood every aspect of it. Was able to do the problems after your explanations
Thanks for this video tutorial, Alvin!
It helped me to understand graphs, graph traversals and most common graph related tech interview problems much better.
He makes it look so easy, wish I had jumped across these tutorials earlier. But will use them now.
34:04 E = N*(N-1) for directed graphs. So in that example, 3 nodes means 6 edges (not 9, as in 3 squared)
Thanks a lot! just finished the first section (dfs and bfs) and it got soldered into my brain! well taught!
Amazing walkthroughs and explanations! Much appreciated 🙏
What a great series! Learnt so much in just under 2 hours!
Thanks to the first 30mins of this video alone I was able to extend the idea of adjacency lists and independently solve all the following problems on undirected graphs and grid graphs in just under a week's worth of practice
As an embedded software engineer, I never learned about these kind of algorithms. This is invaluable knowledge for me, thanks for leveling up my skill!
This is fantastic. Makes graphs easy to digest. Thanks for that.
I did find a minor issue in the island count problem solution.
It assumes that each row will have the same number of columns. That assumption isn't described in the problem. So a quick fix would be to run the nested loop to the length of the row instead of fixing it to zero. And doing the same for the inbounds check. That would present an issue in the exploration in that there might not be any map in either direction, so you'll have to add an existence check in the explore to account for that.
This way if a row has less coordinates, or more, it would still work properly.
Really awesome walkthrough - thanks Alvin!!
Thank you, Alvin.
Your explanation is very clear and easy to understand!
100% the best teacher I've seen. You are legit the best, my dude.
For island count (1:58:20), you actually don't need a visited set to keep track of the tiles you have already visited. Simply set the land tile to water "W" when you visit it; you already have the logic there to skip over water tiles.
Yes, but in real life, functions don’t modify input objects, it’s a bad practice. In an interview I wouldn’t do it without asking.
If space complexity needs to be minimized and the interviewer allows in-place modification, then this is a good approach.
I am following Alvin's last couple of series DP, Graph. Really enjoying his teaching. Appreciate.
Splendid! Alvin is an incredible instructor
Thank you for the video. Also to find the minimum sizes of the island, we can use the method that calls the recursive function (parent method) to hold an integer that points to the size of the visited set before the recursive call and then use the difference in size after the recursive call to determine the minimum size. This to me didn't require me to create a new recursive method that returns an integer. However, creating an extra method does have its benefits too.
Amazing introduction to graphs! Very well explained !
Congratulations on this course, really well explained by Alvin.
Love you man. You make things so easy. Please do more courses. Will support you to the moon.
by far the best tutorial!!! i finally am getting better at this. THANKS A TON!
I literally have no words to express how mind-blowing Alvin is.
Thank you, this helps in brushing up on basic graph stuff :)
Thanks so much for uploading this! The approaches are clearly explained
Great video Alvin. When you describe it, it seems piece of cake. Good job.
wow your explanation is just amazing! Never thought it would so easy.
This was so gooooood!! Watching all the other ones. So glad I found this!
This is awesome! I've been struggling with graphs until I saw this video, great course.
Here because Alvin's DP video was amazing. This is another gem. Thanks!!!
amazing video on graphs. Relearning graphs now and this has been very useful. Thank you!
Wonderfully constructed! Helped me a lot for the unit covering Graphs in my University coursework.
You made such high level topic like a walk in park thanks alot man. Waiting for more such videos from you.
One of the most useful videos I've seen for understanding data structures, awesome
Great tutorial Alvin. For python programmers, here is the pattern for largest components (connected components is similar):
def explore(arr, node, visited, comp_count):
if node in visited:
return 0, visited
visited[node] = 1
for neighbour in arr[node]:
comp_count += 1
explore(arr, neighbour, visited, comp_count)
return comp_count, visited
def largestcomponent(arr):
largest_comp = 0
visited = {}
for node in arr:
if node not in visited:
comp_count, visited_new = explore(arr, node, visited, 1)
visited = visited_new
if comp_count > largest_comp:
largest_comp = comp_count
return largest_comp
thanks for posting this course. Very practical and concise. Great job!
Wonderful video!!! I am familiar with graph now, thank you Alvin💕 I will follow your next video and looking forward to your more courses. Thanks fcc too.❤
Love your explanation , you are the best ! Thanks for the course!
Great explanation, thanks a lot. You are the reason i learnt a great deal about dynamic programming.
please do a similar video for weighted graphs. alvin has the best teaching style. clear concise with helpful drawings!!!
Fantastic. Thank you so much for this amazing explanation!