Recursive Backtracking - DSA Course in Python Lecture 14

[@GregHogg]

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[@Alex-tm5hr]

I appreciate you making the vid greg! vids that explain a concept/algo and then show an example are very useful, not many people doing that

[@asagiai4965]

Nice. Explanation. I might have a question but I still have to think about it.

[@chinmayjoshi2495]

5:52 he better call 'sol'

[@ojxchaos]

This solution is brilliant

[@ceciljoel9577]

this problem came in my coding interview but instead i had to just output the number of subset so i just printed 2 to power n

[@teostorm1]

I don't think anyone could explain this better fr

[@harshgamer6105]

7:40 , so basically, we are doing inorder traversal right?

[@study-me1oe]

Yup

[@ClipGossip]

i think the time complexity should be 2^n * n right ?

[@devoch2031]

Total number nodes in the tree = (2^0+2^1+...+2^n) = 2^(n+1) - 1. So, Time complexity is O(2^n).

[@pianolessonswithbless879]

You said youve covered videos om DFS but I went through your playlist and didn't see it, please can you send me the link

[@aakashs1806]

Very hard

[@biavechiato]

Nobody got me like Greg Hogg got me

[@aryanpratap5853]

First view 😊😊

[@gibs40]

Hardest sht in coding

[@GregHogg]

Yeah it probably is

[@andrewtitus6839]

Glad it's not just me who has had trouble understanding recursion. But it's a good building block for understanding harder problems, like ones involving dynamic programming.

[@barthsparks9791]

I tried this, and it didn't even work.

[@JoatXI]

if you tried it in leetcode and it didn't work, make sure your coding language is Python3 and not just "Python"

[@xingyuxiang1637]

@@JoatXI He probably means conceptually. I would say let the idea about selecting and unselecting be clear in the arguments or function calls. So, in this branch, it is selected. In the other branch, it is unselected. Then, there are fewer global variables to keep track of. Greg's approach is like backtracking for 1-tree or reversing a single-linked list by recursions that can be done easily through combinations API or reversing API. One is probably working on advanced skill sets if one is using this approach. However, global or nonlocal keywords are discouraged at the moment. There are indeed many hard problems. So, one just needs to be very patient to go through the code step by step or purchase a premium to use the debug feature. In my case, I would work on beginner problems mostly.