LOWEST COMMON ANCESTOR OF A BINARY TREE II | PYTHON | LEETCODE 1644

In this video we are solving Lowest Common Ancestor of a Binary Tree II. This is an interesting problem because it's basically a carbon copy of the first iteration of this problem except this time we are not guaranteed to have the nodes P and Q exist in the tree.

[@chasing_the_horizon]

Wow, the explanation was super clear! Thx, mate!

[@crackfaang]

Thanks! Make sure to subscribe if you haven’t already 😉

[@symbol767]

Within in the first 3 minutes of your video I figured out why my code wasn't working. Once I did a check for P and for Q separately first to confirm they both exist, my solution started working.
All I had to do is check if P or Q doesn't exist and return Null, if they both exist, then I can do the normal "find ancestor" code.
But of course this wasn't efficient enough, so thank you for showing me the optimized version

[@FluteVJ]

Thank you . Your channel videos are super easy to understand.

[@jaisoni1]

Great Explanation! Thanks!

[@crackfaang]

Glad you enjoyed the video! Make sure to subscribe so you don’t miss future videos

[@jimmyahmed5424]

Thank you for explaining, it was helpful!

[@crackfaang]

Glad you found the video helpful! Make sure to subscribe so you don’t miss other videos coming soon

[@davidc4322]

Wouldn't storing l and r result in an O(N) space complexity? Since the None value also takes space in memory as well.

[@hangchen]

8:59 sorry I am confused here. If returning 4 or 5 doesn't matter, how would the algorithm make sure to return the correct answer, 5 but not 4?