Pre-order Traversal Algorithm | Tree Traversal | Visualization, Code, Example

A visualization of how the pre-order tree traversal works.

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Animations were custom made using 3blue1brown's animation engine.

[MrAm]

Couldnt understand what my lecturers were teaching till I came into this video, which was explained in terms of call-stack, where my other teachers failed to recognise. Thank you for saving my grades!

[AnupatraRuchutrakool]

IIt takes me so long to find someone who can easily explain the stack frame with recursion. This is really easy to understand! Thanks a lot.

[freeBirbBirb]

best video for understanding traversal BST, thank yo so much

[byte_easel]

I just wanted to say thank you so much. I know how much this time this must have taken writing the visualization animations but your work doesn't go unappreciated. You going over how it looks like at each frame in the call stack was really essential. Also, I really appreciate the visualization of the print output and where we are in the bst. Thank you so much ygong!!

[pal]

I dont understand why we are making a recursive call to the Root. I mean the First Step is to process the Root, thats Not recurisve, so why the 5 gets in to the Stack?

[ragnarokjunekoesco]

By far clearest explaination on binary preorder recursion traversal, thank you!

[pelinegriboyun]

Thank you so much, this really helps!

[عمرصطحي]

simple explanation thank you so much man

[chethanvenkataramaiah]

This is seriously the best visualization explanation so far, but how does it pop things out of the stack by remembering? Like when the control hits the leaf node 1, the left node is null, it returns null, I really dont understand how it remembers the previous execuition of the statement preorder(root.left) was null and proceed to the next statement

[practicalcoder]

can you explain why this preorder(root.right) is automatically called for the parent node even if the pointer is at the child

[BeansEnjoyer]

Wow this wouldve been so helpful back in college. This stuff was a nightmare to me back then.

And now a few years later, I'm needing to rebrush up on these skills to stay marketable for interviews... Thanks

[MeisterMattz]

Great explanation! Your animations make tree traversals so much clearer. Thanks a lot

[nwokolobueze]

Great explanation, the best I have seen so far. I am definitely liking and subscribing.

[kristuze]

omg, it finally clicked to Thank you sooo much

[ahmetokur]

that was by far the best video, thank you so much for this great explanation. The only thing I don't understand is that after we are done leftmost node(1), we pop the preorder(1) from call stack and go to preorder(2) and what stops program to go again to left child of node(2) here. And instead of going to node1 again it goes back to top. i dont understad what prevent going to node1 again in the preorder2 function in the calla stack.

[চর্যাপদ-ট৬ছ]

good video, Can you do this for a post-order video.