Permutations - Leetcode 46 - Python

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Problem Link: neetcode.io/problems/permutat...
0:00 - Read the problem
0:30 - Drawing Explanation
6:08 - Coding Recursive
9:35 - Coding Iterative
leetcode 46
#neetcode #leetcode #python

[@hasferrr]

i think the backtracking solution with decision tree is more intuitive. For each recursion call, you can store the number that has already added to the Answer list into the HashSet, and for each recursion call you can skip the number that already in the HashSet function permute(nums: number[]): number[][] { const result = [] const dfs = (set: Set, pm: number[]): void => { if (pm.length === nums.length) { result.push([...pm]) return } for (let i = 0; i < nums.length; i++) { if (set.has(nums[i])) { continue } pm.push(nums[i]) set.add(nums[i]) dfs(set, pm) pm.pop() set.delete(nums[i]) } } dfs(new Set(), []) return result }

[@riddle-master-ruben]

This is a way better explanation than the old video. I went months with this problem unsolved because I just couldn't understand, but this explanation helped me tremendously. Thanks!

[@bandarupawankumar7549]

Thank you neetcode for again working on this problem :)

[@MyPodie]

Morning Neetcode!

[@pastori2672]

i feel like a time traveler

[@johnveracruz2102]

@NeetcodeIO PLS add a functionality on your site to not show the topics for the questions. want to do them in order without knowing the topic. thanks

[@AVGVSTVSivlivs]

Swapping indices method for this question is probably more clear and you should also review Longest Palindromic Substring question. Solutions in the other questions are quite optimal. Thanks a lot!

[@Gomeroff]

I live in Russia, a new day has not yet begun, and you are already solving a new problem)

[@user-vu4ng4rb8k]

hey also do video for cherry pickup 1 and bst to sorted DLL

[@kanjurer]

I actually just solved the problem yesterday lmao

[@ijavd]

Morning

[@mukeshrawat1304]

Is it possible for you to have some sort of poll or something where we could ask for a video solution of a leetcode problem which you haven't already solved. Because there are quite a few problems which don't have a proper solution on KZbin and God knows when they will appear as POTD.

[@DeathSugar]

I guess thats what his site is for.

[@pushkarsaini2]

Now Solve 31 Next Permutation

[@m_jdm357]

The worst solution I've seen.

[@NeetCodeIO]

anything specific about it that you did not like?

[@m_jdm357]

@@NeetCodeIO I tried to understand it but it's really bad when debugging or writing down on paper. Really hard to understand. I found this solution: def permute(self, nums: List[int]) -> List[List[int]]: res = [] def backtrack(arr): if len(arr) == len(nums): res.append(arr.copy()) return for i in range(len(nums)): if nums[i] in arr: continue arr.append(nums[i]) backtrack(arr) arr.pop() backtrack([]) return res This I got. If no one supports me and everyone thinks your solution is good. Then I'm wrong.