Unique Binary Search Trees | Count all structurally unique BSTs | Catalan number | Leetcode #96

[@bhuwansingh2534]

The only time JEE level maths was used again.

[@prestoX]

Most intuitive, thanks a ton buddy, I was reading Leetcode blogs for 3 days with all crappy methods, yours is simply brilliant and clear !

[@shresthmishra9329]

This explanation helped me to solve another famous problem ''intersecting chords in a cirlce". Thank you tech dose.

[@techdose4u]

Welcome :)

[@vipulsharma7190]

how did you solve that by using this?

[@shresthmishra9329]

@@vipulsharma7190 Because it can be solved using catalan number method. Suppose you a have a circle wihtout any cuts then it is complete 1 unit. But when you make 1 cut then circle is distributed in two parts. (1+1=2). Then when you make the second cut total number of parts of the circle will be 2 parts pahle se the + 2 (because this is the second cut) . Now in total you have 4 cuts. And now if you cut the third cut then 4 pahle se + 3(because this is the third cut). So total parts of circle is 7. Again if make the 4th cut then 7 + 4 (4 becauae this is the 4th cut) So total parts of circle = 11. And this is how it goes on which can be solved with the help of catalan number method.

[@vipulsharma7190]

@@shresthmishra9329 thanks bro for explanation

[@shresthmishra9329]

@@vipulsharma7190 ☺️

[@anitasrivastava983]

The man , the myth , the legend uploads once again!

[@techdose4u]

😅

[@regularsizedpanda]

Coldzera!!!!

[@sujithns5033]

This channel is very underrated. Nice explanation!

[@techdose4u]

Thanks

[@ravipatiramya4185]

@@techdose4u can u share the link where u exaplained Catalan number

[@bhavitmathur5476]

Very Helpful Videos. Please keep posting

[@deepakjoshi4374]

5:21, one small correction, the correct formula will be Cn=∑i=0,n−1 (CiCn−i−1. ) It will go to n-1, not upto n.

[@okeyD90232]

You should add this to your tree playlist.

[@techdose4u]

Sure

[@nagalakshmi1385]

very good video, first time subscriber, want to check out your other videos too. your implementation is Order of n square. Order of n implementation is " long Cn=1; for(int n=0;n

[@BarkaDog]

In interviews, you can be expected to explain more than one approach. So you should always be prepared.

[@techdose4u]

Yes true

[@yitingg7942]

Thank you by watching this video alone I know how to solve it. What about 95. Unique Binary Search Trees II ? I think it's much harder than this.

[@techdose4u]

Yea it must be!! Since you told me 😅 lol

[@rimpiranibaruah5353]

Great explanation

[@techdose4u]

Thanks :)

[@Official-tk3nc]

Great video . I think you are an Indian because no one in youtube could teach better than Indian ...... atleast cse concepts :) ###nitjstudenthere

[@kunalsoni7681]

Such a great video explanation ☺️😊.. thank you sir

[@techdose4u]

Welcome

[@aadityakiran_s]

Hey, your channel is great and your explanations are very nice. I also noticed that your handwriting is very legible. What's the setup you use for whiteboarding? Do you do it using a digital drawing pad?

[@kuangyimeng8850]

very clear explanation. Thank you.

[@paragroy5359]

Nice explanation sir...

[@techdose4u]

Thanks :)

[@siddhartha.saif25]

very helpful. thanks

[@techdose4u]

Welcome

[@chetanpatteparapu7600]

This is very helpful bro ... Thanks a lot..

[@techdose4u]

Welcome :)

[@Utkarshkharb]

Very well explained. Subbed!

[@techdose4u]

Thanks 😊

[@abhijeetkumar2204]

class Solution { long long dp[100000]={0}; int catalan(int n) { if(n==0) { return 1; } if(dp[n]!=0) { return dp[n]; } int ans=0; for(int i=1;i

[@techdose4u]

👍

[@kunalsoni7681]

Helpful video 😊 too much for interview Thank you always

[@techdose4u]

Welcome

[@melwinalm]

As always, great explanation

[@techdose4u]

Thanks

[@thoufeequeshaque3937]

first example binary search tree (BST) structure is invalid . All nodes in the right subtree of a node must have values greater than the node's value. All nodes in the left subtree of a node must have values lesser than the node's value.

[@SuhasSrivats]

In short, this is the formula: Catalan Number = (2n)!/((n+1)!*n!)

[@techdose4u]

Right

[@biranchinarayanpadhi9067]

Brillaint 3xplanation bro!!!

[@techdose4u]

Thanks

[@devanshgoel3433]

thank u sir!

[@orugantilokesh1579]

I am viewing the solution directly , i couldn't think of any method to solve it , is it alright or should i change my approch.

[@BarkaDog]

If you made no progress in 30 minutes then look at the solution.

[@techdose4u]

It's alright. You don't have to know everything. Just keep learning new concepts.

[@ayushganguli1359]

Hi, could you please upload a video to generate unique binary search tree in the range [1,n] please

[@techdose4u]

Sure. That is an extended question.

[@lokeshojha1542]

int count_BT(int n){ if(n

[@meghamalviya8495]

Can you please clear my doubt as to why and how we would have only 3 combinations of 2,3,4 (i.e. c3) in the right subtree when taking 1 as a root? Why won't there be 5 structurally unique combinations at there (for 2,3,4) because we would get 5 as a answer when we have n=3?

[@techdose4u]

Actually C3 means count of no of unique BSTs with 3 unique numbers. It is not an exact value. Think of it as an unknown constant.

[@meghamalviya8495]

@@techdose4u ohk..thanks!

[@SiddheshKukade]

thanks

[@rajaganji7982]

when n=4; C0=0; C1=1; C2=2; C3=3; = C0*C1 + C1*C2 + C2*C1 + C3*C = 0*3 + 1*2 + 2*1 + 3*0 = 4. But 4 is wrong. Please let me know if I am wrong.

[@aayush5474]

Itna mazaa kyu aa rha haiii😀

[@techdose4u]

😂

[@AmanSharma-or5vh]

best

[@alirezaamedeo]

5:22 You wrote Catalan number wrong. It should be C(n+1) = Sigma...

[@pwnweb5734]

AND.. how are we supposed to come up with this formula during interview ? NOP , not intuitive

[@kevinchittilapilly8221]

Can anyone explain why T[0] is taken as 1? If there are no nodes then shouldn't total bst be 0?

[@calvin2042]

No structure is a unique structure.

[@ashutosh61290]

jab sb kuch dusre video se hi dekhna tha toh ye video kyu bnaye ??