Diameter of Binary Tree - Leetcode 543 - Trees (Python) 

Master Data Structures & Algorithms For FREE at AlgoMap.io!

Stumbled upon this after having a hard time understanding Neetcode's explanation. This is so much better!

the best explanation in the whole universe, and don't know why those bad solution vedio got so many views, yours deserves more. PS: I think this problem should labelled as medium.

I think what trips us the most is ensuring we know the definition of height, depth, max height, max depth of a tree and/or node. In some sites, these are defined by number of edges but in others by number of nodes. Once you get these definitions right, the solution becomes even more clear. Thanks for the vid!

You can also just use "nonlocal largest_diameter" at the beginning of the function

In regards to the variable scoping topic: Instead of creating a single field array, you can also use the `nonlocal` keyword as well. Though, it does add an extra line to your code, as it'll look something like this: nonlocal largest_diameter largest_diameter = max(largest_diameter, left_height + right_height)

Instead of using that list trick at the end, couldn't we just define "self.largest_diameter=0" then just use self.largest_diameter everywhere that we reference it? This worked for me : class Solution: def diameterOfBinaryTree(self, root: Optional[TreeNode]) -> int: self.max_diam = 0 def height(root): if not root: return 0 left_height = height(root.left) right_height = height(root.right) diam = left_height + right_height self.max_diam = max(diam,self.max_diam) return max(left_height,right_height)+1 height(root) return self.max_diam

Thank you... crisp and clear explanation!

thanks a lot, by far the best solution i've seen for this one on here

Thank you for this detailed explanation! I ran into the same error with the nested function, so I appreciate you covering that!

Oh wow your explaintations are extremely detailed and clear. Keep it up! Thank you

How are you such a good teacher bro, thanks so much this explanation is awesome

Amazing and simple as usual!

Looks like height computation

Also I believe you can just do nonlocal largest_diameter inside of the height function instead of making it into a one-item list

This must be medium. Thanks alot for the great content.

I have a question. Instead of calculating the withing the height function, i calculated the diameter at the end by using diameter = height(root.left) + height(root.right). This worked for most test cases except one. Why do I have to calculate the diameter within the height function and not after?

could you please expand on why a list is accessible from the scope of the method ?

Your explanations are really good. Please make a video on LRU cache as well

I just started algorithms after doing oop, I feel like Im always one step from solving the problem but I never find that step, is ok that Im going to RU-vid to find the solution or am I ruining my progress. Thank you

can you please tell me which app you are using for drawing while explaining

I believe its not required to pass the same parameter to the nested function that is already a part of the parent function, we can directly access it. Feel free to correct me if I'm on the wrong direction!

please solve more problems :)