LeetCode 14. Longest Common Prefix Solution Explained - Java

[@atefe3919]

No one explains solutions better than you, thank you so much for these videos, they are helping me a lot in the process of getting ready for technical interviews!

[@NickWhite]

thanks

[@joanmoralesf]

Its insane how short this video is but you explained it better than all the long fancy videos. Thank you

[@jay-wf3ft]

I think it would be great if you would show 2 solutions. One with a slow run time and then the optimal solution such as this. It really helps to understand it even more. Either way awesome video

[@pritampadhan5977]

Above logic takes more time i think

[@vcfirefox]

Dude, I am probably much older than you, but goddamn I am LOVING your explanations. Getting a chance to prep my interviews very efficiently!

[@KhayamGondal]

you can add a check for prefix length ==0 at the end of the while loop. Incase nothing matches with the 2nd string then no need to check with rest of the list. And instead of substringing every itteration you can keep track of right index and only substring when returning the result.

[@raghavendrathakur2239]

[@bhargavvaddepally3221]

Damn man that explanation was so smooth

[@ananyadutta6358]

bro your explaining method is quite creative , out of 7 videos based on this that I'd WATCHED , this was the best!

[@prajwalshenoy9117]

Nice one. We can have a case inside for loop to break it when prefix length reaches zero to avoid continuing to loop when there's no scope of common prefix further.

[@poojaupadhyay6364]

such a clear approach! everytime i do leetcode and feel like wtf about a question ,i come here to watch your tutorial and i understand the solution so clearly! thanks a lot,u have a great help dude!

[@suyogsubedi8584]

are you a better problem solver by now?

[@aadhi_dinesh7668]

IN PYTHON s=["flow","flew","flower"] k=s[0] flag=0 a="" for x in range(len(k)): for j in s[1:]: if k[x]!=j[x]: flag=1 else: a=""+k[x] if flag==1: break else: print(a,end="")

[@himanshumalik6913]

You know what, you just explained in a so easier way that no one has explained yet.

[@satyamgupta6030]

what a solution man thanks alot nick brother please continue making these videos. u r just different when it comes to explaining in most optimised ways.

[@vicente3j]

When I search up a leetcode question I always go to Nick White if its available 😂 Great video

[@6066ChetanKhairnar]

got through 3 different videos for a good solution but nick is one who always gives the best approach , Appreciate bro

[@abdelghafourboufenzi213]

but this is incorrect in the case of : "abower","flower","flightwer" the result should be "wer" but the result is empty.

[@syedrehan3251]

Bro prefix means starting of the letter

[@simrankak7045]

Why i didnt find your channel until now. Your explaination is crisp clear and very simple thankyou :)

[@greatred2558]

thanks, tried many things for c# but kept falling out of bounds. This works and simple to understand

[@brucewayne9444]

Wow man. I could have never thought of approaching this problem this way. Thanks a ton👍

[@nurulloabdurakhmanov4914]

Exactly man. What should we do to get into thinking like these aproaches ?

[@ashish4k07]

I thought of using 1st string in array of string as base and scanned through all others and checked if one by one it matches all other strings if it is then we increment the string and hence getting final lcp ans

[@utkarshsrivastava3114]

What a clean and simple approach

[@sreenidhisreesha]

Since indexOf is linear time complexity, Doesnt it make this O(n2) time complexity?

[@tanyagoel9140]

It was so nicely explained. Thanks a lot!

[@prathamchitransh5338]

best explaination for this problem on youtube

[@hbrymiri8301]

Hands best step by step explanation.

[@headyshotta5777]

Thanks for the explanation. I still don't really understand how your while loop works but I'll keep working to understand.

[@carefree_ladka]

indexOf() takes O(N) time . How is your method linear?

[@saradham2844]

Best solution for this problem . Great approach and clear explanation Thanks !!!

[@Noname-di3yz]

the only thing I don't understand is why we can set the first element as the prefix initially... isn't it possible that there is a different longest prefix? ex/ ["ab", "cd", "cde", "cdef","cdefg"], where if we set the prefix to "ab" wouldn't your solution return "" ?

[@syc4654]

probably very late but although the problem doesn't mention it specifically,longest common means that the common prefix must be common for all the elements in the array,so yes,"" would be returned and it would be correct,you can test it yourself inputting your string own string in the Testcase section(In the console) and seeing the expected resulted (from a working code) and your result (from your code)

[@kshitijpandey9376]

You wrapped that up very smoothly. Thanks Nick🙂.

[@divyanshuchaudhari5416]

Great explanation Nick!! Kudos to you.

[@tej3679]

best explanation, you explained clearly kudos

[@dgr8raka470]

I think in place of “indexOf” .. we need to use “startswith” method… tq for the vdo

[@velmuruganjeyakumar1746]

Yooo Man , I too had that same feeling

[@balavardhanreddy8581]

by watching this video i subscribed ur channel

[@thomasgeorge4578]

Man! your explanation is just fire 🔥🔥🔥

[@solomonmokua4643]

Than you, well explained, was able to implement your solution in Python.

[@flyfly11111]

You explained it very nicely. Thank you so much

[@gayan1742]

Time complexity of indexOf is O(n) though.

[@Ben-pb7ct]

Could you explain why the time complexity is O(S), where S is the sum of all characters in all strings?

[@maxstanley1818]

yo but what if the first element in the "fl" prefix array is something like "dog" or something?

[@Thrallgg]

str.indexOf and str.subStr is O(m*n) i think, so I don't think it's optimal.

[@tuckerleavitt]

Yes you're correct, a.indexOf(b) is O(len(a) *len(b)) in the worst case. There is a better solution

[@pranaychoubey9706]

you can eventually shift to stringbuilder i guess.

[@ashish4k07]

So can what can be the overall time complexity for this

[@invictuswildlife]

Kudos to such a clean explanation ! Thank you.

[@ehsanhosseini5861]

Thank you for this amazing explanation. What is the time complexity?

[@royt6924]

I believe it is O(A*S) where A is the iteration for each element of array, where S for the iteration of string

[@amitpadaliya6916]

really amazing solution

[@zerosandones7547]

confusion.Cleared(); THANK YOU!

[@AlejandroRodriguez-lq9mz]

thanks for sharing such solution, very clear and easy one!

[@abhishekmamgain224]

Still you are using While loop and one for-loop. Wouldn't this make the time complexity similar as two for-loops

[@mohammadrafi895]

No, it wouldn't because the inner loop will not depend on the length of input array. Input array could have 100 words but each word can't be longer than 20 characters, on average 5-10.

[@ryan-bo2xi]

what is the time complexity ?

[@rupaldesai7098]

the time complexity is? O(n^2)

[@NickWhite]

Nope because we're not looping through the strs array in the inner loop we're popping characters off of one string

[@suryaakella4508]

@@NickWhite What if all the elements in the string are same like all flowers than no deletion and the time complexity would be O(n^2)? I think we would have to use trie or suffix array to get O(n)?

[@i_deepeshmeena]

@@suryaakella4508 it will be still O(NM) where M is the length of the longest string in the array

[@jardondiego]

@@i_deepeshmeena Indeed, time complexity is O(MN) and space complexity is O(M).

[@jardondiego]

Time complexity with a Trie (prefix tree) would be O(M log N) where M is the length of the longest string and N the number of strings, right?

[@mohammadosama4709]

Why do we need substring method we can check character by character vertically? Wouldn't that me more optimal?

[@ricardosmith5753]

very clean solution.

[@thatsenoughdixit]

Very nice. Commenting so I get more videos.

[@rohitkushwaha6125]

Thank you so much for the explanation ut was really nice.

[@pjguitar15]

I literally got stuck to this problem and I just gave up and went to KZbin lol

[@swagatzeher]

Thanks man Nick... you are a pocket sized dynamite ;)

[@TheRishit99]

Great explanation. Can solve this with Trie Tree ?

[@carefree_ladka]

That's the efficient way to solve this problem

[@freinheit6923]

thank you for explaining!

[@abhinavs2484]

in worst case it is O^n2 right, is there any better solution!

[@KIM-ODee]

Thanks for your explain!

[@pragatikumarprusty7061]

If possible, please tell the time and space complexity as well ...

[@gauravmishra8782]

how did you came up with this solution?

[@jiangtianfeng5971]

very clear! Thx man

[@adil_k]

Thanks for this awesome video

[@LeetCodeSimplified]

Great explanation! Thx a lot!!

[@kso3586]

Amazing! thank you so much👍

[@sameer9368]

hello....please do the problem on the merging k- sorted array using heap.

[@NickWhite]

send me a link in discord and i'll check it out

[@sameer9368]

i am solving in eclipse . i have the problem statement. can i share you that problem statement. i dont know the approach how to solve such problem, i am the beginner. also i am unaware of the concept like heap. please do the video on it

[@abdulqudusyunus9786]

Nice explanation

[@vidhi_bhatt]

simple and on point!

[@Whaleshamu]

can you make video on Gray code (Leetcode 89)?

[@NickWhite]

I’ll check it out!

[@DevanshuMevada]

Thanks Man!

[@srijitdebsarma3451]

Best explanation 😍🥰

[@avinashpatil9662]

What is the time complexity of this solution?

[@makgaboemmanuelmathekga2805]

the code breaks though, with index out of bound error when there is no common prefix

[@shivamd23]

Best Solution 😊👍

[@NeeruSinghK]

great.. nice and easy solution

[@Post2prqbu]

wow! elegant solution!

[@iTzAlwxyss]

How does this not work for processing 4 that uses java ?

[@theolim6994]

Thank you so much for great explanation!!! Helped so much!

[@habibdurodola5728]

Best solutions , Yes you did !

[@davidc3268]

how is a linear solution? theres is a nested while loop inside?

[@whiz-code]

You a genius

[@ruifan793]

Help me a lot, thanks

[@Itachibatman]

thanks don

[@vrindatyagi6744]

THANKYOU SO MUCH

[@gokulkumarbhoomibalan5413]

Really helpful!

[@simardeepkaur8275]

Thanks buddy

[@blaze9558]

thanks man!

[@swethanooka896]

Can anyone explain me the while loop part of the code?

[@jasonliu7186]

Thanks very much!

[@ayushbudhwani]

Nailed it!!

[@fahdagodzo5795]

This guy is smart

[@mohitdangwal587]

you the BEST!!!!!!!!!!!!!!!!!

[@arjun-cw7cr]

thank you

[@sarash9607]

Can anyone tell me why do we set the first string as a prefix ? how do we know it is the longest string and the one that has all the letters that we want ? what if the array was like strs = [ "flight", "flower", "flow"]

[@raghavendrathakur2239]

when program runs it finds common between flight and flower first the common is fl and 2nd iteration it will find common between fl and flow so our aim is to find common in strings so what is there in 1st will be in all the strings if not it returns empty string

[@rajeevsingh5453]

What's the time complexity of this algorithm?

[@aryamankukal1056]

linear

[@akhila5597]

Simply wow

[@shastriswaroop]

How about setting the prefix as the smallest length string and then starting loop from index 0. For longer string array it will be beneficial?

[@MRDELL-mc6zo]

Thanks Broh

[@bty_s]

There is no condition that all array items is started by the same prefix, if this prefix is actually exists. i mean the first ex in the lesson is [flower, flow, flight]. fl - longest common prefix. but in case of [flower, flow, flight, tennis, ten, tenet, tent]. ten - longest common. your solution will not work in such case.

[@deepanshuyadav6815]

So how would u do it....

[@dannytierney2969]

Your second example has no common prefix, as three of the words do not share the prefix "ten" At least, that is how the question is set up.

[@xchen7499]

Thank you, well explained, and very helpful!

[@start1learn-n171]

Tq