LEETCODE 46 (JAVASCRIPT) | PERMUTATIONS I

Hey everyone. Check out this in-depth solution for leetcode 46.

[@PavelS54]

Dude, this is one of those mind-blowing situations where I struggled for hours and you explained it in 15 minutes. Thanks very much. You helped a lot.

[@techchains4428]

For those unfamiliar w/ the swapping syntax:
for(var j = i; j < nums.length; j++) {
// swap the positions
var temp = nums[i];
nums[i] = nums[j];
nums[j] = temp;
dfs(i + 1, nums);
// unswap the positions as we go back up the tree
nums[j] = nums[i];
nums[i] = temp;
}

[@IRLVaporwave]

Are you referring to this part? [nums[i[, nums[j]] = [nums[j[, nums[i]]?

[@jamesaldridge1128]

@@IRLVaporwave yes he is

[@harshupadhayay5520]

thanks a lot

[@xXThUmPerRXx]

I've spent hours trying to figure out this problem. I watched your video once, and immediately understood it with your tree. Great work!!

[@lucasgao5505]

In the tree first swap why swap 1,2,3 to 3,1,2 not 3,2,1 ?

[@andygala888]

Good catch. Yes it should be 3,2,1.

[@ritikbhatt2986]

yes

[@Opacity5]

@@andygala888 pin it

[@praveensaravanan3291]

I was busting my brains over this, thanks for commenting

[@vivienpmc]

This helped me understand recursive backtracking a lot. Thanks a lot!

[@joonpak]

Interesting… this isn’t how I solved this at all (although I too used recursion) 🤯 Amazing how many different ways there are to solve a challenge!

[@isaaca.8731]

great explanation, the visual in the beginning helped alot, got my interview on monday hope I pass

[@user-nj3lg7wi5r]

Thank you very much. I should have thought of that earlier.

[@RicardoBuquet]

Andy I really appreciate your playlist, you are amazing!

[@rimzb]

Thank you, Andy!

[@fufuto]

In backtracking, why do we have to re-swap? we already have the answers by looking at the leaf

[@abdulgaffarabdulmalik4333]

Nice solution, thanks!
I got confused initially, about why you swapped twice😀
But, I think it would be okay to avoid mutating the original nums array.
e.g
for(let j=i; j< nums.length; j++){
let temp = [...nums];
[temp[i], temp[j]] = [temp[j], temp[i]];
dfs(i+1, temp);
}
JS can be tricky at times.

[@DavidK-ex4km]

Hey Andy, I'm not understanding line 21. Why do we need the swap again??

[@LPnotes]

Thanks so much for this backtracking/recursion series!

[@ritikbhatt2986]

very nicely explained thankyou so much

[@aryankali5446]

Dude, I am trying same logic before seeing this video. I am only push the nums as it is in result. I am not understand the reason behind the push as nums.slice(). please u see then replay please.

[@worldwide6626]

Why is it j=i and not j=0 in the for loop?

[@jattinbadrinath]

What does it mean when he says "when we get to the leaf node, we need to scan that" ?

[@coolboyalan]

we will store that copy of array in our result array.

[@bharath_v]

Good One!

[@shibmobileverse468]

What about two numbers? :( [1, 2]

[@SuperKidontheblock]

What whiteboard is this?