42 Comments

1. 

   @CraftAndCodee

   April 15, 2025 at 5:00 am

   At the largest component problem while running the code I got answer 5 when I convert visited as String I got the correct . Anyone please tell me I have paste my code below .
   const largestComponent = (graph1) => {
   
   let largest = 0;
   
   let visited = new Set();

   for (let node in graph1) {
   
   const size = exploreSize(graph1, node, visited);
   
   if (size > largest) largest = size;
   
   }

   return largest;
   
   };

   const exploreSize = (graph1, current, visited) => {
   
   if (visited.has(String(current))) return 0;
   
   visited.add(String(current));

   let size = 1;
   
   for (let neighbour of graph1[current]) {
   
   size += exploreSize(graph1, neighbour, visited);
   
   }
   
   return size;
   
   };

   Reply
2. 

   @BG-eng

   April 15, 2025 at 5:00 am

   That was a great explanation of DFS and BFS! 😊

   Reply
3. 

   @Themaxmerock007

   April 15, 2025 at 5:00 am

   GOAT content! thank you Alvin and freeCodeCamp!

   Reply
4. 

   @kirank3368

   April 15, 2025 at 5:00 am

   This man is a genius and a wonderful teacher 🥰

   Reply
5. 

   @pradeeshbm5558

   April 15, 2025 at 5:00 am

   That's the god level Graph tutorial.

   Reply
6. 

   @rashmin9705

   April 15, 2025 at 5:00 am

   I love the progression he takes, starts off from the very basic and builds up on it , that everything just sinks in! Thankk you so much Alvin!!

   Reply
7. 

   @adeniyitaofik3832

   April 15, 2025 at 5:00 am

   AMAZING

   Reply
8. 

   @santoshkumak

   April 15, 2025 at 5:00 am

   🙏🙏🙏🙏You are doing greatest help on mankind. I will explore all your courses.

   Reply
9. 

   @arunbala9009

   April 15, 2025 at 5:00 am

   I have cleared my first round of interview.
   This video helped a lot. Thanks!

   Reply
10. 

    @YipLseventy7

    April 15, 2025 at 5:00 am

    amazing examples, really helped me understand BFS when cramming for CCC

    Reply
11. 

    @viniciusfilenga4730

    April 15, 2025 at 5:00 am

    what a gem of a course

    Reply
12. 

    @staywithmeforever

    April 15, 2025 at 5:00 am

    10:34 that is wrong basically u move right until u cant, then if u move down first u will check if u can move right inthis case we cant we go down and at bottom we cant mover right or down we move left and then we should move right not left .

    Reply
13. 

    @igustingurahokaprinarjaya7482

    April 15, 2025 at 5:00 am

    Hi @alvintheprogrammer,
    DF traverse recursive version output was not equals with DF traverse non-recursive version.

    Reply
14. 

    @danieladigun2696

    April 15, 2025 at 5:00 am

    This is an incredibly straight forward and simple to understand graph video. This video definitely made me clean up rough edges in my understanding of tackling graph DSA problems. Thank you !!

    Reply
15. 

    @chiomaubogagu7732

    April 15, 2025 at 5:00 am

    This course was incredibly helpful and so well done. Thanks so much! Alvin, you're a phenomenal teacher!!

    Reply
16. 

    @aditi1786

    April 15, 2025 at 5:00 am

    50 mins in and THIS IS THE BEST VIDEO ON THE INTERNET handsdown!!
    Thank you so much

    Reply
17. 

    @d69p-eix

    April 15, 2025 at 5:00 am

    I would never hire someone who uses arrays, sets or dictionaries to solve these trivia problems

    Reply
18. 

    @TheDima23

    April 15, 2025 at 5:00 am

    Amazing course ! thank you so much for this.

    Reply
19. 

    @RaduViorelCosnita

    April 15, 2025 at 5:00 am

    This is truly awesome. Thank you so much for this nice video and well explained algorithms.

    Reply
20. 

    @Singh54321

    April 15, 2025 at 5:00 am

    1:19:56 longest = Math.max(longest,size) can be used

    Reply
21. 

    @Singh54321

    April 15, 2025 at 5:00 am

    the voice, he style of teaching , the animations and visuals absolutely phenomenal. love it

    Reply
22. 

    @mahimapatel8706

    April 15, 2025 at 5:00 am

    42:00

    Reply
23. 

    @Emanuel-yb3qk

    April 15, 2025 at 5:00 am

    Best teacher ever. Thanks for this.

    Reply
24. 

    @TrevorSullivan

    April 15, 2025 at 5:00 am

    Extremely high quality presentation! Well done

    Reply
25. 

    @kavan3

    April 15, 2025 at 5:00 am

    34:29 for anyone confused here, the graph in the example given is incorrect. number of edges is not n^2. To show a graph with n^2 edges each node needs to point to every other node AND also point to itself

    Reply
26. 

    @Dani-zf7cu

    April 15, 2025 at 5:00 am

    Thank you Alvin! I've been trying to grind leetcode and DSA for interviews, and this video as well as your binary trees video was so amazingly helpful and way more efficient than blindly doing problems to help me strengthen the fundamentals, and in particular, I was really struggling with handling how to handle graphs in the form of a matrix rather than an adjacency list — I typically tried to convert it into an AL unnecessarily, but watching this video, especially the numIslands section, made things just click. You also have given me so much of a better understanding and less fear of recursion, even going to appreciation of recursion! That's crazy.

    Also, for the numIslands problem, to save a bit on space, I got rid of the visited set and just set grid[row][col] == 'V' to mark that it's visited, and only add where grid[row][col] == L. This worked.

    Reply
27. 

    @JayDee-b5u

    April 15, 2025 at 5:00 am

    Not sure how the first depthFirstSearch is supposed to end. Doesn't seem like anything ever gets popped from the stack.

    Reply
28. 

    @ohmegatech666

    April 15, 2025 at 5:00 am

    Just have to agree with others that this is one of if not the best course on graph problems out there. Like many, I was intimidated by graph problems early on but this video has made me so much more comfortable with them. I feel like I actually understand them at a deep level now.

    Reply
29. 

    @ohmegatech666

    April 15, 2025 at 5:00 am

    I was confused when you started going through depth first search because you put both of A's neighbors B and C on the stack which seems to be breadth first. But what helped me to understand is the fact that the loop starts when we pop a node from the stack, not when we add it to the stack. The stack doesn't represent which node we are currently "at", the node we pop from the stack does that. The stack is just an in between step. So we don't actually "go to" C at first, we just add it to the stack for now. We do "go to" B because we pop it from the stack

    Reply
30. 

    @thewildweb

    April 15, 2025 at 5:00 am

    This is really a damn refresher

    Reply
31. 

    @kumarankit9243

    April 15, 2025 at 5:00 am

    alvin👍👍

    Reply
32. 

    @avitwito1734

    April 15, 2025 at 5:00 am

    amazing tutor, The best I've seen

    Reply
33. 

    @celeb_intel

    April 15, 2025 at 5:00 am

    I like his lecture, learn a lots, thanks man.

    Reply
34. 

    @ChandrapalSd

    April 15, 2025 at 5:00 am

    Thanks
    You made it really
    easy

    Reply
35. 

    @jerry861200

    April 15, 2025 at 5:00 am

    I am currently struggling with studying graphs, and you are my savior.

    Reply
36. 

    @fandibataineh4586

    April 15, 2025 at 5:00 am

    great video, but i have a minor comment
    at 1:00:34, look at the hasPath function, i would swab the first 2 lines (line 7 and 8), which represent our 2 atomic cases, this way you can use the function to check whether there is a path from src to dst that does not pass through node x, or nodes {x, y, z}

    by calling the function with the visited set already populated with the nodes you want to exclude, this would not work with the current implementation but it still works fine

    Reply
37. 

    @chaitanyashahare2734

    April 15, 2025 at 5:00 am

    This video is game changer!!

    Reply
38. 

    @vaseemshaik4899

    April 15, 2025 at 5:00 am

    How is this stuff free?

    Reply
39. 

    @xmn10

    April 15, 2025 at 5:00 am

    This is awesome, Thank you.

    Reply
40. 

    @David___4n6e

    April 15, 2025 at 5:00 am

    Scientific insights: the significance of refund information

    Reply
41. 

    @James__052j

    April 15, 2025 at 5:00 am

    Poetic revelation: the essence of refunds

    Reply
42. 

    @exploregeographics

    April 15, 2025 at 5:00 am

    Excellent++ Thanks for the course.

    Reply