I would love that Everytime you guess it wrong, we will end up having two problems in same video 😂

T-shirt is really cool!!

I admit it, I'm surprised by this genius simplicity, Thank you!

7:24 This was the cutest part xD "I'm just saying random values"

I did this: if (m == n) return m; return rangeBitwiseAnd(m >> 1, n >> 1)

@Errichto

4 жыл бұрын

Nice!

@koonhanong2267

4 жыл бұрын

Wow, recursive answer

@Paradise-kv7fn

4 жыл бұрын

Recursive solution looks cooler and shorter but is always worse than their iterative versions

In every video something new i'm learning and it helps me to code well than before.

Never seen this approach , something next level

while m n -= (n & -n) return n (-n) will return 2's complement of n (n & -n) will return LSB of n

Educational and informative as always -- thank you!

For the problem in the beginning of the video We can also have a an array with prefix count of 0. And then p[L] - p[R] == 0 : return true Else : return false p is the prefix count array

Thanks for the problem variation with ranges! I probably would have solved that using segment trees. Tackling each bit individually is a good trick; I'd have counted the number of 1s (or 0s) in an interval instead of calculating where the next 0 is though. But that's just personal preference.

thanks Errichto. It was beautifully explained.

your way of bye bye , that's so cool. never change that

thanks bro. It took me some hours to digest your solution after going through it on paper

I did this :) { while(left return right; }

Learning something in every video.

Thank you for the video again! I was checking if numbers are equal I put 1 to the lower bit and shift both numbers right until one of the numbers is zero. int rangeBitwiseAnd(int m, int n) { int res = 0; for (int bit = 1; n != 0 && m != 0; n >>>= 1, m >>>= 1, bit

This guy is on another level

You deserve all the subs in the world.

Hi errichto, love your video can you start a series of explaining and coding complex algorithms? Like lucas theorem, segment trees... It would be a gem.

Nice video! You will not get an all zero suffix when going from m to n. For example, from 5 to 6, 101 - 110, with common prefix 1--. Still, the presented approach works because it is enough to have a zero bit in any number, which will happen due to carries.

it is good that you guessed wrong, we learned two techniques

Great solution!

That's much simpler than my solution. Very clever.

I love your explanations Errichto, thank you for making these videos! Btw, you are on Linux but have a full version of Microsoft One Note? I thought you could only use the web client on Linux.

In bitwise and for range of number[l,r] ,by precomputation you mean to store result for every 30bits of prefix AND at each index right??? And then for getting and of (l,r) for every bit = check if ( result[i][r] - result[i][l-1] == r-l+1) ie.. that many number of 1's is that you meant. or something more simpler...please reply??

As always so easy solution .By the way T-shirt is really cool ...From were did you get this?

@Errichto

4 жыл бұрын

I guess some Codeforces contest :D

Bonus....2 question in 1 video🤩🤩

Any suggestion to learn and practice bitwise problems. I am struggling to solve bitwise problems

while left

Hi, great episode. I am thinking abut constant complexity when dealing with difference (n-m). I am not quite sure if it is possible. d = n - m; shift = d ^ n ^ (n|d); //(other bitwise stuff) return n & (-1

Hello if we didn't have time to complete everything before the end of the 30 days can we do it after?

which theme do you use in geany ?

Your pseudo assumptions 💚 help us understanding new tricks...

Can you please show your hands when you're typing and how did you practice your fingers to code typing ( not just typing ). I mean normal letters are okay but symbols and characters are very diffucult to not looking keyboard.

It can be done using prefix sum of number of zeroes till a specific index, I guess..

every odd no, in Binary ends in 1 and likewise even no. ends in 0. careful with examples Errichto..Anyway Thanks man . YOu're a life saver.

@Errichto

4 жыл бұрын

I don't get your comment. Did I say something wrong?

@satyambhardwaj2289

4 жыл бұрын

@@Errichto Nope....I just meant the random examples you gave in Binary because the corresponding decimal were even you know..

Great Solution!!!

How did you win that t-shirt which contest?

Thank you for these videos. I like your explanations! This is what I produced after hearing your thought process public int rangeBitwiseAnd(int m, int n) { int bitCheck = Integer.MIN_VALUE; while (bitCheck != -1) { if ((bitCheck & m) != (bitCheck & n)) { break; } bitCheck >>= 1; } return m & bitCheck; }

I wish one day i could earn a tshirt like that. you are always a true inspirer!

T-shirt !!! Thats really cool :)

First thing that came to my mind: int bitWise(int n, int k) { int ret = INT_MAX; for (int i = n; i

I solved it by right shifting numbers until they were identical or zero. The concept is the same.

@akramelomrani8728

3 жыл бұрын

yeah and it prevents from overflow it is more recommended

I don't follow what's happening in the "else" how does that give you the correct bitwise & of the values in the range?

@cwagnello

4 жыл бұрын

oh, I figured it out. Went through a couple of examples and suddenly everything was crystal clear.

Thanks man

Thanks

What software do you use to make the visualizations?

@Errichto

4 жыл бұрын

OneNote

superb

Damn,that was fast!

I think you might have thought that "Since I'm wearing codeforces t-shirt, why not lets take part in today's codeforces contest as well" xD xD

@Errichto

4 жыл бұрын

Maybe, maybe.

Briliant!

4:37 the range would pass through '10101 10000000000' instead of '10101 00000000000' 'right? Anyways love the channel! keep posting awesome tutorials please!! :D

@szarusz

4 жыл бұрын

still works though, because from the start of the range you carry over a 0. But that's lucky. I suppose that if you're as good as this guy, you tend to do things right by hunch, without fully understanding why you're doing things right :)

@AnirudhAchal

4 жыл бұрын

@@szarusz haha true XD

@Kekazen

4 жыл бұрын

he says it right at 7:20 anyway

@szarusz

4 жыл бұрын

@@Kekazen not exactly. His example just hides the problem in a different way.

I have more commented code in my solution than code xD

@Errichto

4 жыл бұрын

Well, this is what happens when you don't get it right in the first try.

nice. 3 problems in one

Problem begins at 3:00

which application you are using for writing

@ChristianESL

4 жыл бұрын

I think is msft oneNote for ipad. The ipad version is the only one with dark theme. The desktop or web version are white theme only.

How to get the tshirt? I want to buy

@Errichto is someone fexing CF t-shirt ?? hmmmmmmmmmm .... I mma jealous XD

How do someone get codeforces tshirt?

@RAJPATEL-nm9nz

4 жыл бұрын

In some contests of cf, T-shirts are given as prizes.

prefix sums can also be used right?

@chandrasekharhethahavya

4 жыл бұрын

for the problem you stated at beginning

@Errichto

4 жыл бұрын

Nope, prefixes can't be used for sum or XOR, but not for minimum or bitwise AND. Just think what happens if there is 0 at the beginning.

@Akarirpf

4 жыл бұрын

@@Errichto What about we store the prefix sum of total number of 1s upto position i. sum[i] = total number of 1s upto i Then compare sum[R] - sum[L-1] == R-L+1

@parthsheth5318

4 жыл бұрын

@@Errichto For the bitwise AND queries problem, what if we store an array such that arr[i] stores the XOR of all numbers before i. Then for any query interval L,R we take int a = arr[R] XOR arr[L], and our answer will be arr[L]&(!a). Would this be right?

@CarrotCakeMake

4 жыл бұрын

You could use a segment tree though. Wouldn't be as fast but it would work.

What device do you use to draw?

@SameerKhan-nd5qb

4 жыл бұрын

Ipad ig

@ZzwhiskeybkszZ

4 жыл бұрын

@@SameerKhan-nd5qb Thanks bro

i think this might also work ---> while(n>m)n&=n-1; return n;

nice

When u code, can u zoom the editor a bit for better view, please!

@Errichto

4 жыл бұрын

It's already 125%, are you sure more is needed?

@sounakgupta1372

4 жыл бұрын

@@Errichto no actually I commented during the start of the video when it was not zoomed. Later forgot to delete the comment. Its perfect at 125.

Why did you take 30 instead of 32???

@siddharthgarg5803

4 жыл бұрын

32 bits are numbered from 0 to 31. he didnt take 31 because its the sign bit. not sure though.

@PiyushKumar-ey7qw

4 жыл бұрын

@@siddharthgarg5803 thanks got it.

please be my teacher!!

Why your videos are posted one day late?

@RAJPATEL-nm9nz

4 жыл бұрын

he post sol after time for prbm completed so that if we were not able to solved it we can understand it, even if we have solved we can get extra information. Posting sol during contest is bad thing.

@Errichto

4 жыл бұрын

It's forbidden to discuss problems in 24-hour window after it is published. Even if it was allowed, what's the point in a competition if you can rewrite my solution?

@RAJPATEL-nm9nz

4 жыл бұрын

@@Errichto exactly.

@kishorprasad3817

4 жыл бұрын

@@Errichto I think it's not a competition , people can anyways see solution in problem section going to discussion of a question, the winners will be random I guess.

Is he from Russia?

for(i=0;i

Can I get that t shirt 😏🥺🥺

@Errichto

4 жыл бұрын

I don't have two :(

@akashkumarbhagat4764

4 жыл бұрын

@@Errichto no worries, if you get an extra T-shirt in future (which you will get for sure) you can send me that ;-)

Speak loudly plz