K Inverse Pairs Array - Leetcode 629 - Python

[@FirmamentTSW]

neato!! learned a lot from how you gradually get the final solution.

[@wintersol9921]

I don't know how you do it, put you always explain just the best and the simplest way possible. KZbin coding community is very lucky to have you, thanks man. I learned a lot from you, both how to code better and how to think to solve :D

[@BlunderArmour]

Neato!!! Thank you for the explanation! This is definitely one of those problems where it's nearly impossible to come up with a solution in a time bound scenario.

[@walkastray007]

Its kind of funny because the voice I use in my head for solving problems is your voice. Honestly this was a really well put together video. I really enjoyed how you go with brute force solutions and make optimizations one after the other. This really helps since it shows us how to get from a starting point to something finished

[@simonvutov7575]

Neato! This was super well explained and I felt like I came up with it myself and fully understood it by watching your thought process!!

[@jonathanlo1026]

neato~ I actually watched a chinese youtuber solve this then came to see how you solved it, really loved the detailed explanation thank you, I got a lot from the first brute force dfs as well!

[@shashwatkumar3079]

Always watch till the end because no matter how complicated, this guy can make it simpler only a little concentration is needed.

[@anthonyleong4238]

I actually watch these. Algorithms are my passion, but I suck at interviews due to nerves. I am hoping that understanding these super hard problems conceptually by watching these videos can help me complete all medium/lower hard problems.

[@surajvalluru]

You can get recursive or bottom-up solution to get accepted by putting else break statement in for loop. We know that once k-i < 0 then for subsequent increments only consumes more time. Anyhow this is not optimised solution.

[@hamirmahal]

Neat-o! I appreciate the longer length videos. I think they're very helpful. Thank you for making them.

[@satyamjha68]

Unable to solve on my own !!😭😭 I wrote O(n*n*k) solution but I wasn't able to write O(n*k) approach. Thanks for explanation!!

[@rahulsbhatt]

Thank you so much neato! You make these types of videos with so much clarity! It really helps me out a lot! Thank you so much for the daily content, man!

[@tenthlegionstudios1343]

Made it to the end, spotted the optimization, but I failed to solve this on my first attempt. Also I have never seen an editorial with 7 solutions - this might be one of the longest editorials I have seen for a leetcode problem in terms of number of solutions. Great video! and clear explanation!

[@SanketBhat7]

Neato!! As far as knowledge is gained and content is understandable, doesn't matter how long the video is .. Thanks for the video

[@EvanKendrick-d8h]

big NEATO! Your solutions have been tremendous! I've been learning to code on my own and reach for this channel whenever I get stumped on a leetcode problem.

[@sachinsinghbhadoriya9523]

Neato! This was one of THE problems I was not able to get my head around! Thanks for all the good work!

[@LakshyaSethi-g7w]

neato! never have i ever enjoyed watching a leetcode solution this much! The whole process helped me visualize not just this problem but how to approach a dp in general. Thank you!

[@yaswanthkosuru]

finally after spent hours i cant able to do after seing sliding window pattren + dp i came up with solution within seconds

[@pritz9]

neato !! bang explanation :-)) This is my 778th problem on LeetCode, solved many dp hards, but could not solve this, was clueless for a long time ! Thank You !

[@krishsharvesh8082]

Neato! I actually didn't grasp everything you just told, maybe i need to review dp again , anyways great teaching as always

[@mire5234]

This is ridiculously hard. I cannot imagine someone coming up with this solution during the interview.

[@tkncompsci9353]

Neato!! Excellent Explanation!! I like to watch your videos always whether I know the solution or not.

[@weronikalinda4917]

Neato lol I always watch the whole thing because of your explanations and the path you show to actually get to the solution

[@gitarowydominik]

Neato. In Java the part "total -= prev[N - K]" won't work, as in some cases total can go negative. What is needed is "total = (total - prev[N - K] + MOD) % MOD;" or something similar, like adding MOD when total is negative.

[@binh-nguyen-d]

total includes prev[N-K] so why is the result when subtracting negative?

[@gitarowydominik]

@@binh-nguyen-dbecause of calculating the total % MOD and the underflow of int type.

[@StephanieJohnston-rt7rq]

THANK YOU for this - I could not understand why one of my test cases was an extremely negative number

[@michael._.]

ngl but this is one of the best questions in Leetcode and Neetcode has nailed it down with yet another legendary video (neato)

[@radon3894]

Another excellent video, appreciate the time to explain your thought process!

[@robertyamasaki1807]

neato, first time in a while just silencing everything and looking at the in depth solution

[@PabloElBlanco]

neato, going to have to rewatch this a few times to actually understand everything. interesting and tough problem, glad you made a video about it!

[@aniketpatel8655]

Neato! You explained things very easily. Great approach. Thank you for such solution

[@evanhuang756]

Neato. I went with the DP solution at first .Sliding window optimization is great

[@yashraj3005]

We love you neetcode

[@abhishekkaintura6398]

the way you explain the problem is really appreciable

[@saminhasan87]

neato and neato again!! You have been superb. The way you solved the problem - from brute force to recursive dp to bottom-up dp to sliding window was just awesome. Thanks for the great effort.

[@jasonust3]

Genius solution with amazing explanation!

[@sankalpchordia5245]

We need another algorithms super hard course in the platform!!

[@triputrafauzanhradji8005]

Neato!! I actually get lost since the DP Explanation segment but continued anyway because I was curious about the final solution, hoping I could gain some understanding after watching the whole thing.

[@rohanthakur9159]

Neato!! Just looking at a 10 pages long editorial gave me headache. Thanks for saving me.

[@hackytech7494]

Neato! Well explained as always ❤

[@diegobarbieri7804]

this video is amazing, really clever solution!

[@ahasunos5914]

Neato!! The way you approach the solution step by step ❤️

[@meylyssa3666]

Thank you for clear explanations!

[@विक्रमचौहान-द2थ]

neato! I am a beginner so it was very hard for me but still, I watched the full video and learned a lot.

[@lawlesslotus]

neato! thanks for the explanation, I always jump to your channel whenever there's a Hard problem.

[@AMakYu]

Neato. Great explanation, but what a wild problem. I hope to never get asked to optimize a DP to this point....

[@ridamkrishna]

neato! i watched this video that far because i liked the way we can progress from a better solution to the best solution. thanks neetcode

[@varunpalsingh3822]

neato!! it was a tough problem, but learned a lot, thanks

[@squid84202]

Neato. It's crazy how much optimization you have to do for this one, but I guess that's why it's a hard problem lol

[@sidreddy7030]

Neato! Needed you to come and save the day

[@ameetasom832]

Neato!! loved the optimization part

[@EduarteBDO]

neato. As someone who couldn't figure even the dfs solution but watched everything this is super challenging probably impossible at my current level. I gess that I need to draw more and pratice more

[@phuongnguyenhuynhanh7462]

damn, i solved daily problems everyday and your video is always the highlight of my day

[@anirbansarkar4189]

superb explanation and approach

[@jacquelinejan5898]

Neato～Your videos have always helped me so much when practicing the problems!

[@ElliuHuang]

neato! thanks for going through all the steps to solve the problem

[@jiteshpahwa266]

@NeetCodeIO you left a condition while subtracting from the total for C++ and Java users: if(total

[@kartik6968]

Can you explain what does this do? I was getting the runtime error: signed integer overflow: -1533914095 + -675939082 cannot be represented in type 'int'

[@tizekodnoon8305]

Neato! Head hurting right now 😨

[@piyushgupta7210]

neato! thanks man.. you really are making stuff easier for beginners

[@timlu4734]

neato! Really helpful video, as always. Save me a lot of time, thanks.

[@blurryfca3]

This came on yesterday's Daily question!, neatoo

[@qboff4468]

Neato, you are the best, thank you😊

[@ngoquangtrung234]

Best explication.

[@virgil246]

neeto~ Thanks for the smooth explanation!

[@walkastray007]

Neeto. I didn't make it to the solution, but I did think about the brute force one.

[@leemin-gyu3236]

Neato! Love the videos as well as the idea behind the different solutions :)

[@aswinnath8580]

neato! this is the hardest problem i've encountered in daily challenge.

[@aryanikale7187]

Thank you for this, definitely a hard problem

[@johnj171]

God Father !!! I have made the video so farr you are amazing the king GODFATHER!!! love you content

[@estifanosbireda1892]

Great explanation for a Hard problem, I found it hard to get the recurrence relation even after I knew it's a dp problem. How did you get the intuition for using the relative ordering?

[@mohitkanodia5388]

Neato !! Great explanation

[@VanjeAv]

Wow thank you so much neetio :)!

[@nishantketu2040]

neato👍👍

[@sprajosh]

Neato ~ This is a definitely a big brain problem.

[@arturremizov9296]

Neato Thank you for your videos!

[@ajaykumargogineni3391]

neato!! Great explanation

[@VasudevaK]

Perfect tutorial🤍

[@rileysikes9285]

neato!!!! Another great video

[@Kugelblitz2b]

neato 😭🤓

[@MrKB_SSJ2]

25:40 DAMNNNNN NOTICED THE OPTIMIZATION. IMAGINE SOMEONE ASKS THIS IN THE INTERVIEW MANNN

[@krateskim4169]

Hey neato it was a great video with an awesome explanation

[@swanv951]

In the recursive solution, you only need to take i up to k and not up to n, since we know that (k-i) being negative is going to return 0 from recursive call. That makes it O(n*k*k) instead of O(n*n*k). It is still very bad bad but doesn't give TLE (at least in Java)

[@art4eigen93]

neato! but repeating the whole again, and again.

[@sunilswizy8233]

super explanation neato!!!

[@nikhil199029]

at 12:28, why are donig res = res+ (count(n-1,k-1))?

[@rikthecuber]

Thanks for the soln Neato!

[@aswathchandrasekar2917]

Neato. Nice explanation. But have to come back to it later ;(

[@AbdulrahmanEgy]

super neatooo!🔥

[@hikmetdemir1032]

Could you please make an example training video for backtracking, graphs, tree and sliding window, starting from easy level to difficult level, just like you do for dynamic programming they are very instructive

[@MP-ny3ep]

Amazing explanation !! Neato 😆😆

[@prateekgupta1417]

Neato! Definitely a hard problem

[@yuxiangwang963]

Neato, really a HARD one!

[@bhavyagautam8036]

Neato! Loved your solution.

[@ronbuchanan5432]

Kudos to Neato! (don't you have video statistics though? haha)

[@aniruddhachaki7165]

neato! it's 12:48 am here!

[@ankurbose7672]

Neato!!! How long did it take for you to get to the optimal solution on your own? Just curious.

[@nooobody2751]

neato ! you are the GOAT. Thanks a lot.

[@Cheng-K]

Neato! 🧠

[@insaeq]

great explanation!

[@AdenGolden]

number of permutations of length n with k inversions is the same as the number of permutations of length n with a major index equal to k. class Solution: def kInversePairs(self, n: int, k: int) -> int: MOD = 10 ** 9 + 7 dp = [[0] * (k + 1) for _ in range(n + 1)] dp[1][0] = 1 for i in range(2, n + 1): cumulative = 0 for j in range(k + 1): cumulative += dp[i - 1][j] if j >= i: cumulative -= dp[i - 1][j - i] dp[i][j] = cumulative % MOD return dp[n][k]

[@Kaviarasu_NS]

neato!! big brain solutions ❤

[@erminiottone]

I passed the OJ with the first recursive solution in C++ with TC O(n*k^2) 😅