Sparse Table & RMQ (Range Minimum Query)
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- čas přidán 14. 05. 2024
- Tutorial on Sparse Table data structure. We use it to solve Range Minimum Query by first storing minimum for every interval with a length equal to some power of 2.
problem links: www.spoj.com/problems/RMQSQ/ & cses.fi/problemset/task/1647
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He's the best competitive programmer in my opinion. He devotes so much to the community. Thankyou errichto!
Totally agree 😁
This is the greatest tutorial I have ever seen, soo detailed and crystal clear!!!!!!
Thanks :)
The transition from logorithm to constant complexity for each query had put a smile. That was so cool.😎. Excellent explanation. Keep it going.
I agree that the transition is nice and satisfying.
This is a work of art and beauty! There are people who can do but can't teach. Then there are those who can maybe teach but can't do. Then there are legends, who can do both at a mediocre level. And then God said, "Let Errichto be". 🙌. You make complex stuff seem so mind-blowingly simple! Can't thank you enough!
I think you're exaggerating but still - thank you!
Finally a video that perfectly explains the core concept. I was able to come up with log n approach before you explained and was so proud of myself. And then you dropped constant time which blew my mind. :D Thanks Errichto!
You are the best competitive programmer. Very thanks. I understood it very clearly. Thanks for spending a lot of time to explain us. Thank you Errichto!
Read about sparse table 2 days back. I checked if you had made any video on it. And here it is. 💯
Video quality and explanation is soo good.
Thank-you!!
I was looking for sparse table tutorial. When I saw Errichto's video in the list, I knew I couldn't get any luckier.
Clear, concise, and perfect explanation
Thanks for this amazing course. Your explanation is just in another level.
Amazing tutorial!!! Really enjoyed it and learned a lot!
Errichto this is so nice and simple explanation I read it in book but did not understand you are really nice at explaining
I love even more your recent videos
This is very cool. Eager to learn about the segment tree.
I didn't know about this. There surely are good use cases for this algorithm. For sure segment trees, or a similar structure, are used in databases.
Keep up these good tutorials. Thanks a lot
Finally Errichto is back :)
He is really great and down to earth person....always willing to do something good for community....👍👍👍
that was indeed a really good explanation to sparse tables. Thank you for this video. :)
Thank you! Got mine working now! Awesome tutorial!
Best Explanation, you made it so easy to understand. Please keep up the good work 😊
i love learning from Errichto more than my own profs
Woah explained so simple, seems like a complex math but it is not once you understand the intent behind thanks a lot for the video
I don't understand anything you're saying, but your voice is so soothing like ASMR to me
Lmao, simp.
Thank,I just needed this perfect and Crystal clear explanation .Orz
Very nice explanation Errichto
c++ also has builtin function __lg for base-2 logs with integers. Nice and clear explanation (as always)!
Oh, right.
I think log2 does the same, doesnt it?
@@GGxEpsilon I think __lg belongs to the gcc compiler and is designed to work on integers (or long longs) specifically. log2 should have the same behaviour, but as Errichto mentions in the video: floating point values are scary to work with.
Thanks ☺️ , this lecture was really helpful.
You never dissappoint!
Amazing stuff, good explanation
Dzięki za pomoc w przygotowaniu do Olimpiady Informatycznej Juniorów (:
Thank you, Errichto.
Wonderful video. Helped me a lot sir
Please do some Videos on Data Structure.
Your explanations are simple and precise.
today i am practice codeforces Div2 C problem but i am not able to solve efficiently and seen editorial sparse table algorithm is used then learn this from your lecture then simply solve and learn this concept smart way very thankful for you explanation
amazing dude, I've been following your videos for a year now and you are always improving the way u teach. thanks !
Let's hope that I will keep improving then :)
Amazing tutorial, for so long I was not sure how queries take constant time and not logN time. I always thought we need to answer each queries such that we divide range into powers of 2... finally your tutorial solved that for me that we need to take largest power of 2 which fits in given range and check from L and R end point and hence it is O(1). thank you so much for clearing this :)
Also this clears why we can't use sparse table for answering range sum queries in O(1) because we are using overlapping ranges, right?
Great explanation.
Duma rozpiera, że rodak jest takim mózgiem :)
Erichto you are the best person in the world!
may you get all of what you want in life..i respect you
plz do segment tree.. waiting for a long time..
He's sooo clever. Thanks for the video
Wow! its so clear even a 5 year old IQ guy lile me understands , Thank you for the wonderful content Ericchto !
For computing "k" in the query function we can do k=floor(log2(len)) then we can have 2^k
Very nice explanation
Please make detailed videos on segment tree and it various applications( like, min , max, updating, sum, frequency of max frequent element in the asked range etc...)
What an explanation! op
Thank you !
The brain on this man
Many thanks!
the best youtuber
Amazing👍🏽👍🏽
Awesome!!
You're amazing
This reminds of Reversort in Codejam Quali
legend.
Nice!! Binary is always Beautiful :)
Errichto orz ❤️
Thank you
Won’t the time complexity for answering a single query still logN as we are computing log2(len) where len is R - L + 1 which in worst case is of the order (N). So won’t the time complexity be logN per query?
Can we use sparse table for sum queries if we use the method where we convert ranges to binary and add it like we do in binary lifting (query time = logN)?
Should have checked this out before, not knowing sparse tables cost me yesterday as the seg tree failed in time.
Hello guys, I am errichto, is so cool to hear
Hi , can I know the name of program used to explain pls?
How do you find problems on SPOJ? It seems so difficult to find by tags.
I agree that using log2(x) is something to be avoided generally, however, if x < 2^31, it is guaranteed that the result of (int)log2(x) will be the same of any the bit tricks, so it might be a good choice if it's faster to code.
Errichto can you please make a video on how to deal with burnouts we face while constant coding?
Is the condition in line 30, correct? It does not reflect m[i + (1
Hey Errichto, one question, what do you use in order to write your notes, i think you use like a tablet or something
Can you have multiple overlapping intervals?
It would be nice if you covered CSES problemset. It has a lot of educational problems that are hard to solve if you don't know the right technique.
check out CPH. CSES is a supplementary problem set to that book. Good luck!
Thanks You
awesome
Thank you for this great video
BTW : Is the __builtin function O(1) or O(log) or what ??
It is O(number of bits), so it is essentially O(1)
@@hitesh6856 It's O(1) rather than O(number of bits). CPU doesn't need to iterate bits one by one, it does it faster just like other basic operations like addition.
@@Errichto ohh. I didn't knew that. Thanks! big fan..!
@@Errichto thx for answering
I don't know why people disliked this video.🤷♂️🤷♂️
please do segment trees next
why it is k
you are wrong
pls do video on disjoint set union
❤
💯💯💯
good !
I got WA with this code on spoj, do you guys have any ideas?
Line 27, shouldn't it be i
Can someone explain me what is “1
Search bitwise left shift and right shift on CZcams
Also i think errichto has a video on bit manipulation where he explained left shift and right shift
Here you go :
czcams.com/video/xXKL9YBWgCY/video.html
@@leviackerman9882 Tks u so much
It means 2 to the power k
Thanks for this vid - i like your background - so the goal to the get the O(N*log((N) + Q) though N is increasing tremendously ?
It's O(N*log(N) + Q) so it makes a lot of sense if Q is huge.
2 year's in and still waiting for the segment tree video
We can also solve this problem using sliding window concept in O(n) time
Segment tree can also do the same right? So whats the advantage here?
Time complexity becomes O(N+Q*logN) and improves space complexity too
@@mohansharma-pt6yk in segment tree time complexity is O(QlogN)?
your balance bracket concept apply div2 B problem in contest get Accepted and my rank under 2500 thanks for you good job
:)
What balance bracket concept?
Could u pls share the link of that video 🙏🙏
czcams.com/video/piT58dNLPhg/video.html
How would we handle updates?
You need a segment tree for that.
First View, Like and Comment
Please do make how and when u started doing cp. Love your videos from Bangladesh
10:00 this was when I started thinking that sparse tables are clever.
i dnno, this guy is godtier. I cannot compute. syntax error
Easily explained.
I can AC the cses problem but cant for the spoj :))
It is like segment tree
I have no idea what queries are, and i am trying to learn
I saw this somewhere to find largest power of 2 less than or equal to n:
x=n
While(x&(x-1))
x&=x-1;
Now x will be the answer