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..."

[@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

[@jex3664]

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

[@avory7938]

Hi me

[@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

[@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!

[@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

[@lowtech1479]

This guy has unbelievable algorithms skill!

[@rapoztm5414]

@Lucky Daniel No, world 1 is Tourist.

[@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 😂

[@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 😂

[@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

[@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

[@darkmatterenergy18]

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

[@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👍

[@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

[@vatvuantho9318]

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

[@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.

[@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

[@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

[@thesnups]

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

[@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.

[@zigakovacic4818]

You would make an outstanding CS professor, Master Lin.

[@IAmPantsu]

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

[@vaibhavkumar2821]

FBI be like "OPEN UP" 😁😁😁

[@stinky6832]

@@vaibhavkumar2821 ok

[@YashJain-qr2ej]

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

[@bogicvujadinovic772]

Finally a bit of language that I understand

[@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

[@satvikshrivas1747]

Thanks for this initiative , please explain more for complex problems

[@prathikrm2892]

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

[@aser2535]

William you’re a beast. Much respect!

[@EDENAVIRIC]

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

[@moldoveanucosmin8369]

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

[@sniperkyle6152]

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

[@Suhs1337]

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

[@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.

[@TN-cx4qi]

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

[@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.

[@blaxpow]

Fullmetal Alchemist reference

[@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 😂😂

[@s6031417]

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

[@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

[@calisterwuek7602]

He estado buscando ayuda para recuperar mi cuenta perdida. Todo gracias a cyber_hack55 en Instagram, es un hacker legítimo.

[@elsenordelostamales8815]

Me: HTML hello p> Me: hacker 😎👍🏿

[@nutsirimaunjit7427]

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

[@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

[@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 :(

[@opgamer-uq9vm]

Me trying understanding his code My brain:leave me!

[@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.

[@bogobogo833]

2nd problem is from Full Metal Alchemist

[@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 🇺🇸🇺🇸

[@PLP0321]

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

[@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

[@shujamukhtar4563]

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

[@tingningki2ndGf]

its looks but its not

[@aahanimation]

The speed when he writes for loops

[@nishant_j]

He writes faster than the for loops actually iterates

[@bastianp.8164]

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

[@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 .

[@vineetkothari398]

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

[@naveenverma2390]

yeah it will be awesome

[@ritwik-chakraborty]

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.

[@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.

[@davidlouys3952]

Great content William, you're an inspiration to so many of us ! Kuddos from 🇫🇷

[@sjgabhane]

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

[@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.

[@grvkmr07]

Eagerly waited!

[@AdityaKumar-jh2jz]

Nice explanation. I was ranked under 130

[@fikrialbar2652]

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

[@noobicalcuriosity3436]

True lol

[@jg8644]

Great vid. How are people downvoting this?!

[@stefanirestrepo5027]

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

[@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 :)

[@eduardomlh2001]

The Full Metal Alchemist reference in Problem B tho

[@saritadongre9279]

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

[@gamanabawi7275]

Yeay finally using JAVA!!!

[@jay-rathod-01]

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

[@anant7717]

Keep up the good work man.

[@MarcosViniciusDLL]

I don't understand anything that is going on, but I like it very much. Hugs from Brazil!

[@harshpatel105]

*with masks on. Stay safe ;P

[@MarcosViniciusDLL]

@@harshpatel105 Yes, for sure dude! Haha.

[@harshith3062]

@@harshpatel105 yes

[@plzstop6480]

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

[@muhammadali4]

William Lin will Invent new Language

[@kanhaiyakumar2685]

Really inspired a lot with you

[@rohanmukhija3547]

Great to see you code back in java

[@Crytoma]

Thanks for the content William.

[@TechWithAashubro]

Your friend bruh keep doing these competitive oness

[@x7themm]

Damn he actually made it understandable 😳

[@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

[@iteratedofficial]

This guy can build an OS

[@ByJosecja]

TE CONOZCO HACE 2 MIN Y YA TE AMO

[@vladkruto9469]

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

[@muhammadlutfirahmawan8327]

Finally you use code snippet

[@Lotussss]

You are an inspiration to me :D!

[@reymarkandog1441]

This guy can create his own Programming Language.

[@MiksMaTaunOlema]

i think we have enough

[@reymarkandog1441]

@@MiksMaTaunOlema Yea absolutely :)

[@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

[@gvsharma2643]

This is much much helpful, Thank you

[@nitin8692]

I feel better once I read the comments :-)

[@parvgour5284]

FaceBook Worst Servers doesn't respond when someone clicks to see their friends submissions, It keeps loading and the loading never ends. I think Facebook doesn't have capable servers to run a proper coding contest like Google and it is so annoying for all coders to run their code on different platforms, insert a huge test file as input and then upload output and source code instead, Facebook can implement its own online judge compiler with pre-inserted input files like Google does in its coding competitions only if Facebook Servers have the capability.

[@ritwik-chakraborty]

They must stop this file output system also

[@dislike9589]

William you are the best

[@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..

[@vishalchaurasia96]

This guy is just amazing.

[@hitesh6856]

You are our Hero! ❤

[@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...

[@jameshello38]

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

[@kevinfeng6700]

no i cant read

[@simonhauguel9806]

Just "Fullmetal Alchemist"

[@joezhang2633]

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

[@AbhishekYadav-bw1mz]

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

[@Abadi881]

Ok we get it you’re good.

[@ezizhummedov3607]

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