Remove Duplicate Letters | Leetcode 316

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NADOS also enables doubt support, career opportunities and contests besides free of charge content for learning. 1. Given a string s, remove duplicate letters so that every letter appears once and only once.
2. You must make sure your result is the first in dictionary order among all possible results.
Topic: #RemoveDuplicateLetters #Leetcode316
Used #DataStructure: #Stack #String #Array
#TimeComplexity: O(n)
#SpaceComplexity: O(n)
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Linked Questions:
1. Remove Duplicate Letters : www.pepcoding....
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Smimilar Questions:
1. Remove K Digits : www.pepcoding....
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#RemoveKDigits #Leetcode316 #Stack #String #Array

[@leetcode7091]

You are true gem..... teaching is awesome. Explained like a piece of cake.

[@shang_chi4651]

It's so good to see that you build the soln from scratch right in front of us and debug your code which really gives us an insight. Other teachers just explain the code that how it works but your technique is amazing. Thanks diwakar sir and thanks pepcoding 🙏

[@Pepcoding]

Glad you enjoy it! and If you like our efforts, please upvote the comments written by the students about Pepcoding here (www.quora.com/What-are-the-good-websites-to-learn-data-structures-and-algorithms )

[@ChandraShekhar-by3cd]

Great explantion ever in this Planet! Keep uploading more leetcode contents questions.

[@chauhanabhisheksheshnath2640]

Great explanation!

[@amruthammohan1667]

Best explaination

[@yuvraj2038]

khud se usko koi kaise hi kar paega agar pehle kabhi aisa question nhi kia to. HOLI hai but DSA zaruri hai :)

[@ankitkumarpathak6768]

thanks bhaiya for your all video explanations

[@s1mple965]

thanks man ...your multiple testcase methodology helped me to think !

[@Pepcoding]

Happy to help, for better experience and well curated content sign up on nados.io

[@rohitshinde8478]

Thank you sir your way of explanation with examples is best

[@youngshahrukhkhan8179]

Very Nice Explanation.....Keep making videos

[@Pepcoding]

We will, for better experience and well curated content sign up on nados.io and keep learning.

[@akhilesh59]

Nice explanation Sir, Thank you!

[@AshutoshKumar-es8xy]

Bahaut sahi padhaaya bhai

[@akatsuki1363]

Best👌👌

[@Pepcoding]

Keep learning. And for better experience, visit nados.io, where you will get well curated content and career opportunities.

[@aakashparmar560]

Nicely explained.!

[@letmehelp8927]

amazing explanation sir keep it up thanks

[@sunilpanchal1498]

Great explanation

[@editorera239]

Thanks sr Nicely explained

[@Pepcoding]

For better learning experience watch the same content on nados.pepcoding.com

[@tarungarg9762]

Thanks bro! Really good explanation. Got every point clearly.🤩

[@amansamal8233]

Awesome Explanation!!

[@Pepcoding]

Keep learning. And for better experience, visit nados.io, where you will get well curated content and career opportunities.

[@sharuk3545]

wonderfull explanation.

[@Whaleshamu]

very nice explanation !! Keep making the videos :) Good Luck.

[@indranilchakraborty5949]

দারুন❤❤❤❤👏

[@Pepcoding]

Keep learning, Keep growing and keep loving Pepcoding!😊

[@bhailog_gaming_2000]

Thank you so much

[@satyamabhishek1317]

u r superb sir.

[@_inspireverse___]

awesome

[@istudentlabsindia124]

why time complexity is O(n)? it has while loop inside for loop right

[@theuntoldtree]

👍

[@kannupriyarana4971]

amazing explanation sir🤠

[@divasbhadani9225]

you must teach why you use stack ?

[@16crypt49]

Good explaination

[@prachiagarwal9771]

What's the time complexity?

[@letsdoeverythinginoneweek9398]

nice explanation easy

[@Pepcoding]

I am glad you liked it. I also hope that you are watching till end and trying to understand the what, how and especially why of the problem. If you like our efforts, we request a review g.page/Pepcoding/review?rc You can subscribe to our channel here kzbin.infoabout?view_as=subscriber

[@sahilsaxena8374]

Sir in an interview , What we use HashMap or int[] for frequency map ??

[@yashvarshney6761]

@Sahil Saxena We should use bool array for frequency.

[@mickyman753]

use hashmap first ,then just for optimisations say we could use int[] too

[@siddheshsagar9212]

Hashmap will work !

[@rabinarayansabat9166]

Can we go for TreeSet collection here? It will remove duplicates and provides the result in sorting order.

[@diwakargupta0]

Treeset wont preserve ordering. Example for "bac" treeset will give "abc" but it's answer is "bac".

[@vivekjaiswal3663]

what would be space and time complexcity for this sol

[@shang_chi4651]

It will be linear. Because every element goes into the stack and gets popped only or i should say at max one time. The inner while loop can't execute more than n times in total irrespective of the outer for loop

[@RiteshYadav-rc1np]

time and space will be O(n)

[@satyamabhishek1317]

sir, plz start bit masking series also :)

[@Pepcoding]

Already there, check level2 on website.

[@abhishekkhanna6649]

Thoda attitude sahi kro sir teacher type nhi lgra h waise good explanation

[@trevorPhillips284]

Understood the logic but i failed to implement it even after many tries😫

[@Pepcoding]

Don't loose hope. Its hard to see right now, but its temporary, For better experience visit :- nados.pepcoding.com

[@DhananjayKumar-vn5tc]

run for this test case it will show wrong ans :"cbacdcbc" after line 26 u must add exist[ch-'a']=true

[@srishtikapoor8590]

great explanation