Permutations - Leetcode 46 - Recursive Backtracking (Python)

Please check my playlists for free DSA problem solutions:

My Favorite Courses:

Data Structures & Algorithms:

Python:

Web Dev / Full Stack:

Cloud Development:

Game Development:

SQL & Data Science:

Machine Learning & AI:

[GregHogg]

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

[shreehari]

Greg you have natural talent in teaching, kindly don’t stop making videos

[jonTheDon]

After watching 3 different vids for this problem, this was the only solution where the code made intuitive sense to me, thanks for this fr

[DamosyTheFreckle]

Dude I like your solutions because they are always so clean and the fact that you don't use "pythonic code" makes it so much more easier to understand. So many other people abuse python shortcuts that makes the code impossible to understand

[christianjt]

I learned backtracking thanks to you, thanks Greg!

[AbhishekYadav-ywkv]

such an elegant explanation. Thanks Greg!

[vidhinagda]

Love your approach. So easy to understand

[mhkhan]

This is great. Explanations are so clear. Thank you

[surafelgetachew]

I think both the time and space complexity is O(n x n!), because of copying the the arr in this case sol[ : ].
Also for the space, it's going to contain n! results, and each of them are of length n, and hence O(n x n!)

[arthurpongsapak]

this solution is so much more understandable! thank you

[rathangpandit]

Finally got a hang of backtracking because of you 🙏

[slater-cguy]

This is a really intuitive solution, thank you!

[prannoyroy]

Time complexity is = n! * n (becoz each leaf node is reached in n steps)

[jz]

I think this problem is purely a test of how to code it concisely.
Leetcoding to land a Meta/Google position.
Gotta use code that interviewers can read... so found 3 solutions:
Dupes
Insertion into a growing temp linkedList
Rotations
Took me a couple hours to solve on my own, giving up, then looking it up.

[Techgether]

should the checking of x in sol be counted inside the time complexity? if so, this will be O(n.n!)

[Steel]

Wouldn't the time complexity be O(n! * n) since we're checking each time if x is not in sol?

[arunselvannatesan]

Wouldn't the space complexity be exponential if we consider the recursion stack?

[HemanthKumar-vloh]

Woow ! You made look so simple . Good job. Keep doing such videos

[spec]

been coding for 1-2 months and im getting into these, my brain hurts

[saleheen]

My brain hurts.
Kind of understood it after watching many times