Remove K digits | Build lowest number | Leetcode

This video explains a very important programming interview question which is ti find the smallest number after removing K digits from a given number. This is a very interesting and also a very important question. At first glace, it might seem easy but it has many special cases. I have first explained the possible cases and then the intuition for solving this problem. This can be solved very easily using a stack. At the end of the video, i have explained the
CODE and shown some more special cases and how to handle them. CODE LINK is present below as usual. If you find any difficulty or have any query then do COMMENT below. PLEASE help our channel by SUBSCRIBING and LIKE our video if you found it helpful...CYA :)
CODE LINK: gist.github.co...

[@fullysimplified7139]

Can't be explained better than this... Million times thanks for making these questions so simple :)

[@nishanksoni7120]

You are doing too much hard work dude.Wish you best of luck for your future endeavours.

[@techdose4u]

Thanks :)

[@gracioussaxena8318]

Did you just fire the guy lol Great job though Tech Dose, well explained!

[@nirajgusain1452]

Hey there, I am from year 2022, I came back in time to give you good news that ,Surya sir(tech dose founder) has joined Google.🥳

[@codingwave56]

@@nirajgusain1452 wow ! 🎉

[@bharathik6479]

Wonderful way of explaining the algorithm behind the program. Most channels only explain(show) the code. Please keep up this great work. Please do mostly asked Leetcode medium questions. Will be a great help. Thanks a lot.

[@techdose4u]

Welcome :)

[@dallasgannon5717]

Sorry to be off topic but does any of you know of a way to log back into an Instagram account..? I stupidly forgot the account password. I would appreciate any tips you can give me!

[@johnnyzyaire602]

@Dallas Gannon instablaster :)

[@dallasgannon5717]

@Johnny Zyaire I really appreciate your reply. I found the site thru google and im in the hacking process now. Takes quite some time so I will reply here later when my account password hopefully is recovered.

[@dallasgannon5717]

@Johnny Zyaire it did the trick and I now got access to my account again. Im so happy! Thanks so much you saved my account :D

[@blynch2496]

Perfect, clear explanation to a problem that I've been stuck on. Thanks so much!

[@techdose4u]

Welcome :)

[@amritanshu83]

Very nice explanation better than other explanations out there which just throw terms like greedy etc. Giving concrete examples and explaining the algo through them makes it much easier to understand.

[@techdose4u]

Yes....term confuses students 😅

[@sundeep1501]

Your explanation is really good and with O(N) which is better. I solved this problem with different approach and I think the time complexity id O(N * k). Is that correct? Step 1: Parse the string left to right. Step 2: For each current char at i, See if there is a char lesser than the current char in window [i+1 to i+k]. If found, decrement the k and skip the char. Otherwise add to the result. Here is the code: public String removeKdigits(String num, int k) { if(num == null || num.length() == 0 || num.length() 0){ builder.delete(builder.length()-rem, builder.length()); } String res = builder.toString(); return res.length() == 0? "0" : res; } int getMinIndex(char val, int start, int end, String num){ if(end >= num.length()){ return -1; } for(int i = start; i

[@yadneshkhode3091]

your time complexity is N^2 and space complexity is also N

[@AmanShukla18031992]

The explanation was really awesome bro. Gave a whole new perspective to look at numbers. Really appreciate the effort. Sincerely, thank you.

[@techdose4u]

Welcome :)

[@ytg6663]

Explain

[@dayanandraut5660]

One of the best intuitions I have ever seen. I love the way you take examples to derive the logic. Keep it up. And also thanks for delivering such a quality content on coding problems. You just earned a subscriber.

[@techdose4u]

Thanks

[@0anant0]

Awesome explanation! Thanks! As per the explanation, just remember this: Remove previously seen peak elem to flatten the curve. When graph dips, we have already seen a peak.

[@hitenarya4987]

this channel should have millions of subs.

[@techdose4u]

Thanks bro :)

[@greatbrothers2947]

This channel work so hard i wish this channel should have millions of subscribers

[@yitingg7942]

This is absolutely mind blowing. Couldn't think of this approach.. 😭😭😭 Also so many edges cases to handle... But great great video.

[@sudhanshuverma1987]

Awesome explanation. You’re doing a great job in helping the community.

[@bhavyapandey]

An inspiration for anyone who wishes to learn or teach DSA

[@techdose4u]

👍🏼

[@sameera2426]

It was such a great explanation. Half way through the video and I knew what to do. Keep up the good work.

[@ShubhamSharma1210]

nice .. this is a good explanation. the good part is you are telling more examples that make more sense for everyone.

[@techdose4u]

Thanks :)

[@aamirjamal6833]

I wish I could like this video more than once. Thanks for your explanation. You are good!

[@techdose4u]

Thanks 😊

[@santoshreddy3]

Your explanations are best I have found on KZbin.

[@techdose4u]

Thanks :)

[@shivangshukla4243]

God level explanation bro. Been watching your videos since a month and they are all brilliant. Will definitely donate once I land a job :)

[@techdose4u]

Thanks for your appreciation.

[@xapeuuu]

Glad i got the stack approach by myself even though my code was way messier than yours ^^

[@techdose4u]

Many were not able to solve this. Glad that you did :)

[@PhenomenalInitiations]

Can you please explain why in line 15 he consiered only when stack is not empty?

[@culeforever5408]

great explaination

[@lanpingdeng1094]

great explanation, easy to follow and understand. thanks

[@techdose4u]

Welcome :)

[@suryanshgupta7518]

wonderfull way of explaining..

[@techdose4u]

Thanks :)

[@ujjvalsharma5055]

wonderful video. Great explanation of code and intuition. Keep up the good work

[@anshimagarg9661]

I'm so happy that I found your video. I understood it very well. Thank you very much sir.

[@techdose4u]

Welcome :)

[@Darshil1771]

Became fan of your explanation! Much much appreciated!

[@techdose4u]

Thanks :)

[@satyakidas7297]

Amazing intuition explained. Thank you

[@paragroy5359]

Nice content. Keep on making such videos

[@kaichenghu3826]

Very good explanation and visualization

[@techdose4u]

Thanks

[@akashsingha2616]

Great explanation brother. Understood each and every step. Keep doing great work.

[@techdose4u]

Thanks :)

[@azadsingh8466]

Dude, congrats on 100K. You deserve it

[@techdose4u]

Welcome 😄

[@dhruvvarshney1040]

kya baap tarike se sikhaya bhai. Mja aagya. Thanks man

[@techdose4u]

❤️

[@collegeworld7494]

Best concise explanation

[@red_and_black_UA]

great job, thanks for good quality of explanation

[@techdose4u]

Welcome 😊

[@AyushRaj-gf2ce]

extremly datailed explanation..thank you so much!!

[@techdose4u]

Welcome :)

[@harkitnebamake]

Pretty good explaination bro ! I was able to solve it in my mind but couldn't put it in code . DIdn't think about first-come maxima approach . Cheers (y)

[@techdose4u]

Nice

[@samridhshubham8109]

Wat an explanation, absolute gem

[@rajeshbammidy180]

One thing to notice here if the elements keeps on increasing as he said it will form the smallest number possible that means we will have the higer value digits at the end so we can remove them easily with the help of the stack

[@techdose4u]

Yes correct :)

[@spetsnaz_2]

starting the day with your video

[@techdose4u]

;D

[@asliddinburiev5143]

Simple and perfect explanation!

[@niteenautade]

Beautifully explained.

[@jashhinger442]

Great explanation sir, Thanku so much

[@techdose4u]

Welocome :)

[@RahulKumar-oj4lz]

Great Explanation

[@techdose4u]

Thanks 😊

[@kkgirl543]

This is an amazing explanation! Nice question, thanks.

[@techdose4u]

Welcome :)

[@shrijonbiswas8105]

This is a phenomenal explanation!!

[@adarshsasidharan254]

man what a brilliant explanation

[@rajeshbammidy180]

Java solution using Stack:github.com/RajeshAatrayan/InterviewPreparation/blob/master/src/Stacks/RemoveKDigits.java

[@techdose4u]

Thanks for sharing

[@rajeshbammidy180]

@@techdose4u As always 🔥 But you didn't answered my question

[@agileprogramming7463]

Initially I thought this is a DP problem because I thought we have to consider all possible cases and the do the DP thing... but this approach is really wonderful.

[@techdose4u]

It could have been dp problem if you thought about recursively solving this.

[@harishvemula6709]

Sir , the way you explain is absolutely amazing !! . Wish i had a teacher like you . Greatwork Sir !! :) :)

[@techdose4u]

Thanks :)

[@SaiKiran-dy6ke]

Man, wonderful explanation.. Highly appreciated.. 💞💞

[@techdose4u]

Thanks :)

[@Shubham-zu1zh]

good explaination

[@hapysethi1306]

Bhai thanks alot for sharing Algo Code and Explanation

[@techdose4u]

Welcome :)

[@karansagar7870]

Great approach

[@techdose4u]

Thanks :)

[@thelimit9719]

Perfect implementation !!

[@techdose4u]

Thanks :)

[@akhilesh59]

Nice Explanation! Thank you 😄

[@anuplohar23]

Nice Explanation

[@himangshushekharjha6972]

Simply Awesome! Keep Growing!!

[@techdose4u]

Thanks :)

[@aakashbhatia]

good explanation

[@sparrowsurya96]

I got a goodone idea to solve this say we have the number 71382 and k=2 so what we can do is that to divide the digit by its index number, index number must be starting from 0 ie for 7 index number should be 1 not 0 and so on,, then after we got the list of the divided result we can just chose the minimums possible and then we can include only those in return value, me testing this got all correct result for almost all cases

[@sanketsuryawanshi]

Very Well Explained sir 🔥👍🏻

[@techdose4u]

Thanks :)

[@crankyinmv]

Thanks. I hate your 4's but the overall the video was quite helpful. I solved 402 with a different approach, but wanted to see how the stack based approach worked. No I know.

[@techdose4u]

😅

[@anil7931]

Thanks for clear explanation !!

[@techdose4u]

Welcome :)

[@tirthjayswal9895]

Good

[@abhishek__anand__]

Great Video

[@rahulchaubey8988]

Nicely explained..

[@techdose4u]

Thanks:)

[@nikhillingam4630]

Best explanations ever

[@techdose4u]

Thanks :)

[@jolly_dollyyy]

Lucid Explanation!!

[@techdose4u]

Thanks 😊

[@kushgupta1187]

Very well explained

[@techdose4u]

Thanks :)

[@vaalarivan_p]

0:00 - 8:59

[@vishalbhatane1608]

Thank you very much!

[@techdose4u]

Welcome :)

[@codesnippets03]

Amazing 👌 explaination

[@techdose4u]

Thanks :)

[@vishnuparegi4580]

👌

[@techdose4u]

👍

[@luanaamorim5055]

thanks so much, great explanation!

[@techdose4u]

Thanks

[@sleepypanda7172]

pure genius!

[@oladimejijames9554]

nice work sir, please keep it up. Kudos

[@techdose4u]

Thanks :)

[@vm1662]

Amazing stuff! Thank you.

[@techdose4u]

Welcome :)

[@deepeshdragoneel3351]

Wow such a beautiful problem!

[@Arunkumar-pg8kx]

That was amazing,

[@techdose4u]

Thanks :)

[@vaishnavikulkarni8104]

Amazing sir

[@techdose4u]

Thanks

[@abhishektanwar7902]

Amazing👌

[@techdose4u]

Thanks :)

[@ninehoursful]

How does one come up with such intuitive solutions? I tried to come up with multiple solutions but was not even close to this solution. I tried to solve this question using priorityQueue, HashMaps, expanding from center of the string.

[@ShubhamSingh-fl3qi]

This helps alot ThankYou sir

[@techdose4u]

Welcome :)

[@kongzilla2897]

Nice and clean :)

[@sachinduhan3022]

amazing explanations man...

[@techdose4u]

Thanks :)

[@rajnisharyan6361]

hey, can you please tell me about how you are wrinting are you using digital pen and which software you are using for writing

[@rohits22013]

good explanation man

[@techdose4u]

Thanks man :)

[@shaamidrees6036]

Thanks

[@ritikthakur2445]

nice explanation ❤❤

[@techdose4u]

Thanks :)

[@raghavendrasinghchouhan17]

I was also approching the same way, but stuck in one TC i.e "1234567890" where k=9 op = "0" this will give output 1 according to this approch. Correct me if i am wrong

[@secularph8424]

I was waiting for your explanation,

[@techdose4u]

:) This video was little longer and I was very tired after office 😅

[@secularph8424]

@@techdose4u its okay Usually, I complete the task in the noon and compare our solutions in the night But this i couldn't do it, so I was waiting for your solution 😂😘😘

[@ojobabatunde8415]

As in, so i was

[@techdose4u]

😅

[@spetsnaz_2]

me tooo....

[@noblejoy1432]

I used deque instead of stack so as to maintain the order in which we fetch the result.

[@techdose4u]

Nice

[@istiyakahmed4117]

nice explanation! keep it up :D

[@techdose4u]

Thanks :)

[@gauravkumarpandit7022]

please make a video on heavy light decomposition and centroid decomposition

[@techdose4u]

Sure....will add it to my to-do list

[@srini580]

Thank You Sir!

[@techdose4u]

Welcome :)

[@marlegagaming1274]

Nice, but how can you get such idea in an interview ?

[@techdose4u]

Practice :)

[@abhishekrai4325]

Sir ji aap great ho. Is there any way we can contribute even a little towards your hard work ?? Sir please let us know. And again, thank you so much for such a wonderful explanation 💙

[@techdose4u]

You love and motivation is everything I need :)

[@abhishekrai4325]

@@techdose4u We love you 3000 Sir 🥺 keep up the good work and we'll always make you proud.

[@techdose4u]

Thanks :)

[@sukeshreddy2286]

You are on fire!!!!

[@Amit_Kumar_1999]

do you have any sort of material which can give proof of these algorithms? like build the lowest number & finding the next permutation. Though I know how to solve these problems, but I stuck at proof.

[@techdose4u]

No material available with me. I don't think we need proof for simple problems like these. For complex problems there is confusion and when we don't really understand why the given algo works then proof is required. But I don't think this problem requires it 😅

[@codetrooper9279]

leetcode gave me this edge case for the following problem : "9964143637881536115347130215819342018286368478941148499497648482711459533461004254405644237053081606083361703097681313409879305615510320200854934444651935440830730707105506511273844202022847156939479617415032308016122590196433883734152425324321850950025461922368309179936567772058238956815658522566619712309337787110000248140248621983725541138216249932119341652497227527347196915584874245747655643373728114771002178121013476532176128561227651191732455258556988215663509467036265356759614472865379500702323093381756610448863769645016608790510082369942579876359844432606935705284237991853585529691576005445931743352187877817181108107659316666309094802979311362685246271238811648377471342618391148123088439359424933182816550379826963424443077369303388270800024963285014879985932202469314657763554311465766241899886051752598919297325070163176559846505309761680481734434389501672456194786083611750491579701118513267425527823659774604213876847372305982594830156571943761073290766254549904295349986681374115730100337100520099231426507753102943794893125561715341714882235592831859851753324171964100271220487416100160426921656692822076747471313551671799749136336020476415426498900467136354109743348482211848364210754765858145061682176996476703252113885157082272913476246001426543322720172472400433849455239728009056816478610972157143620619838281484903385698733878747333577266693321881082248284899461049170566515551638479945941859455913682794110638768950164185110174329858257546630386490667378849662828892086742219395018081013139661291385111259380764915297206827929993411346366971457561364592936565292180883672568239002607555932099570488014976458337969750530347455002905982811683646920337042844933044228156313556893574266924334421860399441795570348505986213235968877629037821039295531078587452820520378855971549385240599138029027426814355797039844185115797752068944043026514402978978851104279587917456738135851069474951293893468797930509914957546422062980494255056416478680885689780986382412165954803439553973540706927945767861390922237184889229475493329909116465687108626908432452951254474743412354718972999375833762203809869944881570164493465129271906768322772743880895596954354231919788356736973386736425035313669786510718228292965591836221183232782757135478753561150173194385615500385373233981959493952471916956111069857167656232936080328221546753405850472812773151559894114363782701095557909245140582135212670655043831517604969231621049089970261307870253571673590180617152285302103559731670339047857148567799820792277393882937146083861121444641752891357528477673783704643969540852343441491634297968882019783645863769499154099829169034519420545243923982738295303981036771224459015594039438755491178665247811195429718554410638417459245168087508373787473581006876786621492463488551382880888016193098727660257087286075211981304241455039635843389359277754175667320688287674673170776696626809610432006193791350589302883359213754039606437515551397976472818092708306048112752211824002614062564731378390107393841924024992900096272203427395268363591954016973222085497810130812644667188518603229549084506011656716594567797567298132136216194941840585237878858460280261239887687428829375605555945753827119720586750631367716075599073634731471504260724387869378014436808380008096784296619353982377042796709113277023048503614322336338787624495889957753806917512300465195258871128700879115968204258194381296288237529334846252325708114045756734861206974694332984226429182357067126837458065169631111462435830423526194589462766826719275660644126448562809748092006285700764039691021497055662341656594078963665734973515004383619424206199423404426260428435029625839720828715873547773951561589009316755538926217057660908236519924235235619770675436108507917722314466270142484807060731907806830319044273720218636481802179286069057173343243951397675980777851315120680118430072968591076578558637383169959517835261015038328382345688129364776302241168625264064812069025112090263137082552535421329754943044198941936240688824218041364039700546228900283717808668314344125472252807531518791099498692946306328235067764410531248477081885126875518308672990452448890110228731016986585572535897645362817103841400441546963512425504489024589005011590124360348938492006792308704507061642951011458749395538490335711130206859554892150422217109609854841320808883156074499689978384411831818569414262079698400452210643442851321588188354275888886257603641542109776241390729041700493644160923820461710058687648706149758610663198374013955557327262668118696927211331534855305270845371631301081119472690423140645543286568447703696095356440639011578632338858560471650438477891281241072990894958114372212031895484984653567691286852652650107819350239352406247153415410489981573464865003560861111332722204086414609128602020530497009851004558213098998166539307648066090774246910719321947561845561811551635349521128959781556450619336828717871420898920647009920722717177061958022742777205857695854934254785056637106031433088913246626097291550078584270096661510394983107568852284638963599007835813868746666309926509943177567423764071146627260987232909089440658715419840948643405694899164262372586852026108171450189145270495456283424448569589948515079403390259530337163259718494052568455827222239581358795056659883657572871140467289486985130119950834544281691454027423177357369504911743323275056434347729657191133645133876512280190549218912402169969802021783116006137524974034884121177247645508906187095351048025633571322832319878202674281722032124798012166778080087780121953281154213990048080361508373995751341852800925384965505331299553457430714895272762787031887232509441186074980915540748406598710173038534657124879846721233591082115228641107791579039749775647761305136598794351890975921125276308162602613620947449084111833733277311612206315241420877680167161438220399831080179104610998046479515377590428457920804676517029937657171269635939119530901104658094509911834532916480786646162451345985896947826134836574624284225410044907484601816238164950877120569238794304908387715612875323938649830559994913847735846142427346403699764243535207474309469556453569337817388828063386673201871070106075270225888456218745849251418102741904560860713975379774169322590092343616327329178404794610285957334113599535194067297494574506232093110791623246072201088665182707451600906528066716801778296466352116847226315589109436913458461169480262043362176721412417396263618014297812863894569241927022251843236338212810026054491745524431816261936080879721415400139684005152086524990911977362327604478399623548495844170253366109533533745860373292406811347654427322004062128727816870739347150484269231235478226556874230536777363555700806568810979064871335057235179992463827382981618762627934240748675861788419966966928608060895764016209642774439752210302641378269815873258179000071675149007690634648402383570243847410517693177906568998013034783715505630346774249951596571304595795422559205980746291728274910535867306471613576584967759160806132390501968761657940111783971926932724300758693836556821231163843128368094607938898908079852172177082531123738229964097723172239004001873306000872671136917795579250480587166095227513303636144825722216217410612188695684620857717590021703108526077575365136576503892571795469501972023565367296868901957326265446043677290076577561548925783488235294134907367257567056159306138787933767323329430647993503126831151518641629962296657851797867581892758511834434836115871075631305313171629312419298203797778937978212212065639949848860893174395253604154645329950104157745622961822125351922490661182775122039377762364257753265392919143960318300488002198280753602322178959901050212568772400468517743851667463897673688774948011835714122935517858871877786651062920273375111055933492403860770905970985397924956951021275562795431502500806645371609682567723668096992175087712673025694981107705697503168637056584581698103616789233045510349716540798432279251526556648379633827348804287772844732893364577341009306236568268726801331893106555271701367417282270428827919746197880594428541322028499930384974054042989302540781012005370199906430319556272687007906821384315109437884645847116815976336340146845907247443530043331401570136363370530915319618701366471761797561864822781675495147435474205623389661981530587155618059093419177544645023243506433417343485533346526216034151725020954864421131237384144102474077299206755740534997886723627476115663811233372206043170460623060506091246306386543951687123557178508806912199010111871"

[@ojobabatunde8415]

Thanks man

[@techdose4u]

Welcome :)

[@anonymoussloth6687]

I am a bit confused about this problem. lets say we have the number 143. When we delete 4, 1 takes its place since the new number will be 13 and 1 is in the tens place where 4 was. So why do we look at the number right of the number we delete if the left number takes its place?