Depth-first search in 4 minutes

Depth-first search in 4 minutes.

Sources:

[bigchhet]

You explained in 4 minutes what my data structures professor failed to do in 1 hour. Thank you!

[ahamedshathelegend]

My professor was great at teaching DSA but I missed classes due to sickness and various reasons today I have a test I am don't know what I am going to do but thanks to you, your videos are short sweet and minimalistic ❤

[WillOfHeaven]

I had already seen your search and sorting videos, they were concise and helped me first understanding how it works and figuring out everything else in the process, helped the cogs of my brain move a lot !

[francescoercole]

Ehy Michael, I only watch your videos because your explanations are clear (many slides) and straight to the point. Thank you

[ВиталийЩуров-шн]

Consice, straight-to-the-point and very easy to understand! Great video!

[elinaliu]

such an underrated channel, you help me so much in reviewing these algos. thanks!

[adamlangevin]

Just stumbled upon your channel and all your videos are so short yet informative. Thank you!

[antoniooliveira]

if you could also explain uniform-cost search, depth-limited, iterative deepening and bidirectional would be amazing ! great vids, learning a lot from you.

[darshsingh]

brother said im going to teach you DFS in 4 min and went on to teach DFS in 4min. kudos

[esmondkim]

These videos are so incredibly well done, efficient, and helpful. Thank you!

[abhishekmaurya]

Thanks a Ton! I have my data structure exam today 😁.
Welcome back too 🥳🥳

[meXD]

Great video! A have a question (probably stupid, but anyway) about mapping your explanation to your code. So this video says: stack is a list of nodes to be visited;
1) 'A' is a first node to be visited
2) Add it to stack (to be visited)
3) Pop it from stack
4) Mark as visited
5) Add adjacent nodes (to be visited) in stack
...
Now according to your code for dfs:
1) 'A' is a first node to be visited
2) You add right away 'A' node to visited array ( visited.append(node)) before popping, so it's marked as visited?
3) You add 'A' node into a stack (to be visited) but 'A' is already been visited according to visited array
4) 'A' node is popped
5) Then you loop through 'A's adjacent nodes (G first) (for n in reversed(graph[s])) marking 'G' as visited ( visited.append(n)); pushed into visited array
6) Then you put 'G' into stack to be visited (stack.append(n)). But 'G' is already in visited, isn't it?
7) Same as point 6) happens with 'B'
8) Pop 'B' from the stack
...
Then algorithm proceeds with other nodes pushing into visited before popping them
So the question is: am I getting something wrong? What is the indicator of nodes to be marked as visited: being popped from the stack or being pushed into visited?
Again in short:
-The video states: Add node to be visited in the stack -> pop it -> mark as visited -> add adjacent nodes to the stack -> repeat
-And according to code: Mark 'A' as visited(push to visited array) -> add 'A' to stack(to be visited) -> pop 'A' from stack -> loop through 'A's adjacent nodes (mark 'G' as visited, add 'G' to stack, mark 'B' as visited, add 'B' to stack) ->pop 'B' -> repeat
Hope I explained my confusion well. Trying hard to get DFS right so I'll be waiting for your response, thanks!

[Jordan-pmzx]

Thanks a lot! Currently working on Cracking the code interview and found this. Short and precise enough:D Keep it up man.

[_benon]

the right video to be free from confusion

[RaquelNatali]

Thanks a lot for the new videos!! Hope you are back definitely!

[studywithrichard]

A stack only has two operations, push and pop. They do not let you add the 3 elements C, D and E before G as you did in the 3rd step.

[xinglinli]

I'm so happy that you start to post videos again.

[asimov]

Thanks man. Perfect explanation and understandable code!

[rafaelfreire]

I never thought about dfs as the "opposite" of bfs... thank you

[matusdzoba]

Hello, great video.
I would like to ask you some additional question. List of Stack and list of Visited will be on the evening like this?
Stack: A, B, G, C, D, E, F, H, I
Visited: A, B, C, D, E, F, G, H, I
I am not sure if the List of Stack should preserve all previous values or it is changed continuously.