Facebook Hacker Cup Qualification Round 2020 + Explanations

[@nishant_j]

He writes faster than the for loops actually iterates

[@乌雅成璧-g7m]

lol

[@ben-uy1ud]

Watch in 2x speed...is another high 😁

[@c.ravindra3626]

please do some small hacking vedios bro please

[@nkdenim8371]

lol

[@pythonanimalia]

This guy will solve world hunger.

[@wickhere7996]

You will also do that 😁😉

[@BlackHermit]

But in what time complexity?

[@charlieduong528]

Using java

[@Manu-wb2uv]

If he would focus on that

[@DarkH4X0]

"Let's use a DFS to find the shortest path to the market with the lowest avarage price in the town..."

[@jex3664]

“It’s very straight forward” Bro I haven’t finished reading the first step yet.

[@avory7938]

Hi me

[@skumji3880]

Maybe you should make a video about your coding journey. Like how you started and got better etc. I think many people would find that interesting!

[@adityaband6919]

Yeah that would be interesting

[@productivepoy6885]

As I know even though he is 18, he was coding about 7-8 years.

[@cryfan6828]

I support

[@potatopotato4676]

@@productivepoy6885 I think 3-4 years

[@garricky1811]

I agree. I'm learning programming, too

[@AM-space]

im here just because the keyboard`s sound. so satisfying

[@MikeLGMFX]

😂😂😂

[@ibraamibo]

Where can I get this shit?

[@Katoph]

@@ibraamibo just search mehcanical keyboard

[@zempt7764]

@@Katoph it doesnt sound like a mechanical keyboard, it definitely sounds like your typical membrane office keyboard

[@tenx3]

The fact that he takes time to explain what he’s doing🙌🏻

[@nutsirimaunjit7427]

It requires certain amount of profession to convert image in your mind to serial speech, if one can do it at ease, they are insanely good

[@als5321]

Will: That pretty much sums up the solution. Me: When did it start?

[@jasoncavanaugh1556]

As a first year compsci student who has mostly worked in java and eclipse, it was fun watching you work through these problems using tools that I'm more familiar with. Keep up the good work!

[@ruantristancarlinsky3851]

He read that in 30 seconds....Me pauses for 5 min just to get a glimpse of what's happening

[@CardinalHijack]

Its because he knows what hes looking for. Hes not reading the entire thing - his skipping to parts which he knows he needs to read. Think of it like reading cooking instructions, if you know what youre doing you can go straight to the method, you dont need to read the preface or ingredients list. If you really know what youre doing, you can even explain the preface, what type of cake it is and ingredients list without reading it, just from looking at the method - its the same for programming essentially :)

[@SMR8344]

Practice makes you perfect

[@EmanuelLopesS2]

How is supposed to get a job in IT when this guy exists?

[@TheKillerZmile]

He can do everything bruh

[@otpreet]

how is what

[@maxmesaa]

IT Job doesn't require such skills. They will not give you a math problem for solving. They will call you at 03:00 am and say "Hello, our servers are down. Get them up in 30 minutes." Coding challenges requires math and algorithm skill instead of coding. IT and Software Development requires algorithm, coding, copy-paste, stackoverflowing, googleing, lying, bug-fixing, testing and too much coffee.

[@TheKillerZmile]

@@maxmesaa LMAO

[@morindamanik2961]

@@maxmesaaLMAO 😂

[@saad-ul4mr]

Next video : I dethroned amazon and microsoft in 6 hours

[@random7983]

using java

[@charlieduong528]

With explanations

[@rarespopovici4402]

With windows lol

[@morindamanik2961]

only using Microsoft DOS

[@LayfonSuohu]

I think I wasted my 5 years studying programming 😂😂😂😂 C, C#, c++, Java, java script, html, php, DBMS... but least I'm little bit confident in creating 'hello world'

[@AkashKadam-vp6vm]

Same dude 😂

[@lowtech1479]

This guy has unbelievable algorithms skill!

[@rapoztm5414]

@Lucky Daniel No, world 1 is Tourist.

[@srinitumuluru5573]

Communicating on what your thought process on each step while doing all this.. N that's what matters when you work with teams.. For this You ranked No. 1👍

[@ashbjorn]

The first question really reminded me of that Google mock interview you did a while back :-)

[@pinchcactus1061]

Yeah. I thought so. But the first question is just linear and not strongly connected components.

[@darkmatterenergy18]

This guy is so talented. If only you had been my prof in highschool, maybe I would have like programming.

[@IAmPantsu]

for some reason i read it as "FBI hacker cup" XD

[@vaibhavkumar2821]

FBI be like "OPEN UP" 😁😁😁

[@stinky6832]

@@vaibhavkumar2821 ok

[@HiPh0Plover1]

it just help to see how much you can imagine stuff and focus the whole time , don't aim for google lin , your best bet is gonna inventing and selling a time machine

[@mohansivadhas]

Bro congrats on ur videos. I am gonna graduate this year. I am doing my graduation in electronics, also doing intern in a product company. I got this intern by learning basic progs, now im beginning to see coding as FUN. Gona peek into CP .keep posting new videos

[@davudsafarli5356]

Thanks. It really helps to see how you solve questions step by step. Looking forward to see more videos like this.

[@thesnups]

This was really helpful! Thanks for taking the time to explain and walk through your thought process.

[@theElectrASiAN]

Wow, you are fast! :O I participated and solved Travel Restrictions and Alchemy - so 25/100. I used C#. See you on Round 1. Lol. xD

[@kartik_exe_]

bro u are unmatchable ok btw i am really really inspired by u when ever i open my pc for cp i first open your vid and starts learning

[@retry0x3f3f3f]

need keyboard cam. I can touch type the letters but not special characters like " ' < > ? { [ ] } ( ) \ | etc. I'd like to learn that from you. (perhaps, can you make a video or something about this?)

[@a.sana04]

He probably has long fingers. Like I have them, and I over shoot something lmao

[@Brandon-mw8pk]

I'd almost guarantee he has a ton of macros setup for his characters. Super easy to do if you have a keyboard capable of it. For example, he could press CTRL + A to get { or CTRL + B to get }, etc... kzbin.info/www/bejne/Zojdan9sidapbbM

[@morindamanik2961]

@@Brandon-mw8pk thx dude, now all make sense

[@zigakovacic4818]

You would make an outstanding CS professor, Master Lin.

[@satvikshrivas1747]

Thanks for this initiative , please explain more for complex problems

[@perpetualgod5038]

Try to use Linux instead of Windows, i guess you'd really like it coz you enjoy to use something "unusual" like Vim, Eclipse etc.

[@suvidsahay]

William: C++ is not helpful for to know about what kind of error you encountered I tried solving D1 but got a segmentation fault during the final submission in one of the test cases. It took me a day to realise that I need to increase the stack size. FML

[@kaustubhdamania5362]

Ikr! The same thing happened with me. I realised later that I should have solved it in a bottom up manner :(

[@vatvuantho9318]

This is one of the best programmers I've ever seen

[@vineetkothari398]

Are you going to use java from now on? That'll be amazing for java users!

[@naveenverma2390]

yeah it will be awesome

[@ritwikchakraborty1702]

No he is not going to do just did for hacker cup file input output

[@cwagnello]

His Java language knowledge is lacking. I wouldn't recommend he switch (as a person who is a Java developer) unless he plans to give up on C++ and he would never do that for other competitions since that would put him at a disadvantage.

[@blaxpow]

Fullmetal Alchemist reference

[@aprilynastoveza6799]

I am actually learning how to program rn and I cant understand anything and I really want to cry and I am really frustrated and stress rn and Here I am still watching this stuff and I am still okay I guess

[@DKYtut]

Competitive programming is different than 'normal' programming. If you want to learn programming there are tons of tutorials. For learning purposes you have no benefit watching this video's. This is for people interested in competitive programming.

[@aprilynastoveza6799]

Hi haha I think I just randomly click on this bec. I was super stress that time but still thank you for commenting, this is very helpful for me.

[@StickAndPotato]

I have degree in IT. Graduated but didn't learn in depth programming. Now I just want to become a nurse.

[@moldoveanucosmin8369]

I was blind the entire time, had no idea what this guy kept doing in discord with that white theme turned on

[@bogobogo833]

2nd problem is from Full Metal Alchemist

[@nicolasmeinerz3548]

I feel stupid when compared to this guy.

[@kinstar]

do you ever think to yourself, oh lord this is the person i have to compete with xD

[@92subi92]

You are

[@kinstar]

@@92subi92 loooool

[@nicolasmeinerz3548]

@@92subi92 Wow! Thank you for the sincerity lol

[@jaeger4763]

You could become him or even better bro

[@shujamukhtar4563]

the first question looked similar to the question asked by clement mihailescu

[@tingningki2ndGf]

its looks but its not

[@troys1426]

In Problem 2, I just got the count of A and B, then checked if the absolute value of ->(a’s length - b’s length) == 1.

[@mramanpokhariyal6388]

Did same by observing the I/O pattern of sample test case but don't know why my one test case was failing.

[@EDENAVIRIC]

Damn bro, you make it look easy. Shit like this inspires me to try be better at coding fr.

[@opgamer-uq9vm]

Me trying understanding his code My brain:leave me!

[@saritadongre9279]

Please make a video on MIT admission procedure (you applied for SAT or what)

[@YashJain-qr2ej]

You and errichto are the best. You both have helped me to learn various concepts. Thanks

[@prathikrm2892]

I'm demotivated by looking at how good this guy is😭

[@natoisnazi]

The only guy who will always win the argument with his girlfriend...

[@krishnagaming1467]

by using for loop

[@HAL--vf6cg]

Programming and girlfriend are an unusual pair. Money from programming, however...

[@shiestynayak9711]

@@krishnagaming1467 will probably break from the loop asap

[@sniperkyle6152]

He makes me feel good and depressed at the same time. 🙂

[@perfectgamer9208]

Can We take a moment to appreciate The skills he had developed. It must took loots of hardwork over many days👏👏👏🙏

[@Discontinued-Acc]

this sort of understanding doesn’t come from just days, it takes years

[@தமிழோன்]

Rust is a perfect replacement for C++. Its standard library (especially std::collections) has all the stuffs needed for developers to be productive. Although Rust is a systems programming language like C++, it looks and feels like high-level languages like Java. It's also less verbose than Java! How cool is that?

[@ElPikacupacabra]

LOL, it's not less verbose than Java. It's about the same.

[@fikrialbar2652]

He said : So far i think it is pretty simple 😅 Me :.....

[@noobicalcuriosity3436]

True lol

[@aahanimation]

The speed when he writes for loops

[@nishant_j]

He writes faster than the for loops actually iterates

[@elsenordelostamales8815]

Me: HTML hello p> Me: hacker 😎👍🏿

[@bogicvujadinovic772]

Finally a bit of language that I understand

[@dom4287]

omg that fma reference in problem b xdd

[@trilogyxs5357]

I know im late but how long did it take you to really perfect your skills??

[@alexismandelias]

A lot

[@mohmmadqudah2331]

like alot alot !!

[@_Aniket_]

He was born with a laptop in his hand...

[@bastianp.8164]

He goes "i think so.. Yess" im like, yeah no i stopped thinking reading problem 1

[@Jeram08]

how can I even begin to practice to be an ace on algorithms like you? 😭

[@ericj8889]

Don’t compare your progress to others, focus on yourself and yourself only.

[@stefanirestrepo5027]

Meet alexander__hacker70 he’s the best on iG🏆he help me get back my account 🥰 Thank you so much alexander__hacker70 🇺🇸🇺🇸

[@pratikghule3862]

I didnt understand the solutions and logic .., can you make a video explaining it on white board... please!

[@cwagnello]

Have you tried using the other IDE's for Java (Netbeans or Intellij)?

[@eduardomlh2001]

The Full Metal Alchemist reference in Problem B tho

[@omarabozein7015]

William do you find c# as efficient as other languages in competing ?

[@PLP0321]

Will: uses drawings to explain algorithms. Me: Hey look, tic tac toe.

[@gamanabawi7275]

Yeay finally using JAVA!!!

[@jay-rathod-01]

but how did he use "uunderscore" as a variable?

[@AlexandrBorschchev]

Whenever I watch William's videos and streams I just kept thinking about all the time I could have spent for practicing for competitive programming. I could have been fluent in linux and mastered c/c++, python, java, haskell, and a lot other programming languages if only time was spent wisely.

[@Suhs1337]

I made it to the end. Love all the vids. It did help for sure I like the line by line commentary.

[@joezhang2633]

Dude, how can you come up with the coding of the segment tree as created by yourself online ?!!

[@aser2535]

William you’re a beast. Much respect!

[@mrmartinwatson1]

I can't believe im the same age as this dude

[@aayushchoubey4874]

how old is this guy

[@mrmartinwatson1]

@@aayushchoubey4874 shouldn't be older than 18

[@majdkhasib76]

i can't believe i am older than him

[@deepaktiwari2847]

He's just a High school student.

[@jayantjha3128]

Me too, kid

[@AbhishekYadav-bw1mz]

Hi William, will you ever make a video on how you started your journey as a programmer? Thanks!

[@naxxiiimarquez9461]

how did you jump to the end of the line, the cursor if you're already inside parentheses, don't tell me it's just with the arrows, that's rapadio if so ohh

[@s6031417]

I did enjoy this video because it helped me to observe a part of life of a genius.

[@TN-cx4qi]

171k subs 172k views. I'd say people are on the edge of their seats waiting for your content.

[@youssefbenhmida4408]

hey William, i really love your vids bro. I recomend to you to get a mechanical keyboard , it is a joy while coding and typing. Keep it up !

[@mohansivadhas]

Hehe... Really? Im gonaa try coding in my pc .

[@wthxrsh]

Which keyboard he uses? As a programmer, that keys sound is satisfying...❤️

[@TienNguyen-uv8hs]

Ohh no, his keyboard doesn't sound good at all!! U should check out Teaha Type on KZbin to see what satisfying is like

[@LetsTalkBackend]

How did you thought the approach of D2 as a segment tree. Can you please make another video for its detailed explanation ??

[@mohamadalibaydoun6418]

He started with a standard DP, but since the dp transitions essentially involved minimum of a range, he used the standard technique of having a Segment Tree instead of a DP array. This way, he can query minima of ranges in logarithmic time and make point updates in logarithmic time.

[@73dines]

Can you split your screen in three parts? Task description, editor and face cam.

[@nutsirimaunjit7427]

He's average when he can write code He's wise man when he can explain

[@akashagrawal9374]

Which ide do you use?? On codeblocks such big test cases doesn't run

[@ezizhummedov3607]

William are you using normal touch typing, just please make a video about your typing technique with hand camera, PLEASE!

[@ashishg7216]

You got me interested into coding, I really wanna learn from the scratch and be able to code like you someday.

[@Yannnus]

It's impossible, forget about it....

[@kent0n144]

​@@Yannnus why would you say that

[@Yannnus]

@@kent0n144 it was a joke, obviously, but I really think that this guy is a code genius and it's almost impossible to code like him :)

[@tzzzzzs]

What keyboard are u using?

[@HDbIce-oj3wv]

Why didn't William use System.out.println but used out.println? I'm new to java.🙂

[@sjgabhane]

Thanks for making the video! Please make similiar videos for all rounds, helps me a lot as a student.

[@kishorprasad3817]

Please upload screencast of every leetcode contest you appear.. it's okay if u don't provide explanation during contest..

[@krishnavamsi4534]

He shouldn't show his screen during live contest

[@kishorprasad3817]

@@krishnavamsi4534 He uploads screencast of leetcode after the contest where he ranks best.., lately I noticed he is taking part in almost all leetcode contest, but doesn't upload video. I need to learn how he debugs the code and solves question..

[@shariqshaikh5715]

william can you please tell me how you have made your logics that much strong please tell me i also wanna do

[@mudarhussain2408]

I don't understand anything but still watch it again and again 😂..........btw in love with those keyboard sounds😍

[@chandrakharismasungkowo599]

Same as hell. My brain gonna freeze when see william solve and type the program's under 10 seconds 😂😂

[@plzstop6480]

So here is a joke, I failed calculus yet for some reason I’m watching this.

[@ravikawalkar934]

Plz suggest laptop which should I buy for learning artificial intelligence n phyton

[@dgprasad9855]

How you are solving? I also very much interested in coding but iam not able to do so can you please tell how to learn coding...

[@utkarshsaini5650]

I don't know why am i watching this video even i am not a cs student lmao

[@AdityaKumar-jh2jz]

Nice explanation. I was ranked under 130

[@kanhaiyakumar2685]

Really inspired a lot with you

[@kiosx7388]

just a curiosity why not c# instead of java?

[@N_Henderson]

Looks nominal. You should check if the nominality is nominal within the nomils. Should be nominaled at that point. Nominal

[@Abadi881]

Ok we get it you’re good.

[@sundaehang5590]

what device u using?

[@rohanmukhija3547]

Great to see you code back in java

[@jameshello38]

0:12:49 Any one else noticed the problem is from Fullmetal Alchemist:Brotherhood 😂😂

[@kevinfeng6700]

no i cant read

[@simonhauguel9806]

Just "Fullmetal Alchemist"

[@meghraj1998]

Is there anyone in the comment section who actually understands what he’s typing?

[@didyoustealmyfood8729]

the question he is solving are not easy to understand... but if you are a programmer then you can easily understand what he is doing but you need to repeatedly pause the video... this guy is very quick and fast... he is literally doing algorithms in his mind and then straight away typing them which crazy if you think about it.. but i guess he has practiced for this like crazy for it

[@meghraj1998]

@@didyoustealmyfood8729 how many years of programming do you need to do to get to this level?

[@user-ge7ep5sc2d]

@@meghraj1998 he said he started coding around 9yo, now he's 18

[@HajjSejj]

What type of keyboard is he using?

[@vladkruto9469]

Wow, I wish I could read and understand math problems this fast haha

[@danielc.6644]

Can you share the functions to read the inputs please?

[@typestream6599]

Can I know what were your grades in high school.