Quicksort Algorithm: A Step-by-Step Visualization

In this video, we will take a closer look at the Quicksort Algorithm and its implementation. We will start by explaining the basic concepts behind the algorithm, such as the pivot element, partitioning, and recursion. We will then walk through a step-by-step example to illustrate how the algorithm works through a step by step visualization.
Quicksort Algorithm is one of the most widely used and efficient sorting algorithms in computer science. I will show you how to sort an array from least to greatest. It is a divide-and-conquer algorithm that recursively partitions an array or list of elements into smaller sub-arrays, and then sorts these sub-arrays in place. You also need to select a pivot, and for this video we always pick the middle index. The algorithm was first developed by Tony Hoare in 1959 and has since been optimized and improved upon by many researchers.
Additionally, we will cover some of the key features of Quicksort, such as its ability to handle large data sets and its performance characteristics. We will also discuss some of the potential pitfalls and limitations of the algorithm.
By the end of this video, you will have a solid understanding of how the Quicksort Algorithm works and how it can be used to efficiently sort data. Whether you are a beginner or an experienced programmer, this video is sure to provide valuable insights into this essential sorting algorithm

[@ethanaustin_17]

After watching a bunch of videos I finally came across one that I understood!

[@QuocDatPhung]

Thank you Ethan! Please kindly share with your friends and subscribe to support me (it means a lot) ~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@LUCAZAMA-or2dt]

It's been two hours searching for a decent quicksort explanation and came across this great video, consider taking the path of the teacher if you are not already into it. Much love

[@QuocDatPhung]

Thanks a lot Lucazama! You can find all of my CS videos like Quick Sort in the following link (don't forget to share with others and kindly subscribe!): czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@LUCAZAMA-or2dt]

@@QuocDatPhung do not worry about it, i have already done all of that

[@QuocDatPhung]

@@LUCAZAMA-or2dt Thanks so much!

[@ConorLambert]

Absolute best video on Quicksort.
I was looking at other vids from people with millions of subscribers and nowhere near as good as this.
Thank you my good friend.

[@QuocDatPhung]

Thank you for your kind words Conor! Please kindly share with your friends and subscribe to support me ~ also you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@jeremysmelley7143]

This is definitely top 2 quicksort videos i've watched. Highly underrated, this helped a lot, thanks!

[@QuocDatPhung]

Thanks Jeremy! Please kindly subscribe and share! You can find all of my Data Structure videos here: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@abramweigant2438]

I never leave comments, but this video was incredible; good job, man!

[@QuocDatPhung]

Thank you AbramWeigant! Please kindly share with your friends and subscribe to support me (it means a lot) ~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@MariusCiutea]

I can't believe how well explained this is! And I'll never understand why college professors seem incapable of explaining in such an easy to understand manner.

[@QuocDatPhung]

Thank you for your kind words Marius! Please kindly share and subscribe~ all of my CS videos are in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@g.r.4372]

I was 100% from beginning to end. You're a great teacher.

[@QuocDatPhung]

Thank you G.R! Please kindly share and subscribe~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@oshawastaken]

This is by far the best explanation of quicksort on yt, thank you!

[@QuocDatPhung]

Thanks so much! Please kindly also check out my Merge Sort video: czcams.com/video/ho05egqcPl4/video.html

[@Bromon655]

I watched a lot of quicksort videos and this was the first one that clicked with me. Well done

[@QuocDatPhung]

Thanks a lot Bromon! You can find my other CS videos in this playlist: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@khoadoan8966]

Bro, you're amazing, explaining the complex processes so easily. Haven't touched DSA for a long time, and then having to learn it all over again after being laid off is really hard for me as I'm not as young. You've just helped me understand fuzzy complex knowledge really really well. Thank you !

[@QuocDatPhung]

Thank you Khoa! I'm really happy to hear that! Pleased kindly share ~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@khoadoan8966]

@@QuocDatPhungI’ll share it, and have a look at your playlist. Really appreciate your contents.

[@user-oh2tr8vw1u]

Very clear and correct explanation. Thank you so much for making an effort to explain this the correct way!

[@QuocDatPhung]

Thank you! Please kindly share with your friends and subscribe to support me (it means a lot) ~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@KnochenMarkSaege]

I've watched a few videos on this topic, and this one helped me personally the most, by far. Thank you for taking the time to explain in detail every step that is necessary to achieve the wanted effect. Also, explaining how the code behind it works really helped me grasp the concept.
Thank you very much for your effort :)

[@QuocDatPhung]

Thanks so much KnochenMarkSaege! I'm really happy that you found my video useful! I have an entire playlist on Algorithms; you might also like my 3 min Merge Sort explanation: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@harrygray9887]

outstanding work amigo. I was expecting thousands of comments.

[@QuocDatPhung]

Thank you so much Harry! Please kindly subscribe and share with your classmates. It really means a lot. Also, if you like my Quicksort video, you might also like my 4 min Merge sort video: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@annarankin9103]

Thank you Quoc, this video has been very helpful.

[@QuocDatPhung]

Thank you Anna! Please kindly share with your friends (it means a lot) ~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@mm-en1rf]

I appreciate the video greatly, I went through 2 other quicksort videos and this was the only one of the three which I could easily comprehend.
I'll be sure to visit your other videos when it comes to understanding more comp sci content !!

[@QuocDatPhung]

Hey there I'm really glad you found it helpful! You can find all of my CS videos in the link below (don't forget so share with your classmates to help them too!) czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@strawberriesandcream2863]

best quicksort video i've watched that helped me clarify the concept :) thanks!

[@QuocDatPhung]

Thanks so much Strawberries! I think you'll like my Merge Sort animation too! Please check it out here: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@st-lucia]

Thank you!

[@QuocDatPhung]

Thanks so much, St-Lucia - Castria La Patria! Please kindly subscribe! You can find the rest of my Algorithms videos here: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@JacobChencha]

That was a beautiful explanation!

[@QuocDatPhung]

Thank you Jacob! Please kindly share with your friends and subscribe to support me ~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@ananthaprasetya3263]

Hi sir, why we need to swap array L and R with the same index? both already the same value.. Thanks

[@QuocDatPhung]

The algorithm will still swap them even though they are the same :)

[@lowe7372]

Best explanation, and best mindset to approach the algorithm. The game example is AWESOME. Thank you very much! please do more

[@QuocDatPhung]

Thank you very much! I have an entire playlist of my Algorithms; I hope you'd enjoy my Merge Sort video as well: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@stormShadow64]

awesome video, very clear

[@QuocDatPhung]

Thank you! Pleased kindly share and subscribe~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@NucEstFemicomunismo]

Thank you. Best explanation

[@QuocDatPhung]

You're welcome! You can find all of my CS videos in this playlist (don't forget to share and kindly subscribe!): czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@Harshavardhan-pk3pk]

good explaination must watch

[@QuocDatPhung]

Thank you! Pleased kindly share and subscribe~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@awieeeee]

hello, what if the mid index results in a decimal value? what number should i choose?
the values are (5,1,8,4,3,9,6,2), so
mid index:
m = 0 + 7 / 2 = 7/2 or 3.5
where should the pivot be placed?

[@QuocDatPhung]

The formula for calculating mid at 0:25 has the floor sign (meaning to round down). So if m =3.5, we simply round down to 3. Let me know if that makes sense! You may also like my Merge Sort video :)

[@romanvolosiuk3919]

It really helped me. Thanks!

[@QuocDatPhung]

You're very welcome Roman Volosiuk! Please kindly subscribe! You can also find the rest of my Algorithms videos in this playlist: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@phoenixkomben-ie9xq]

Great video

[@QuocDatPhung]

Thank you Phoenix! I think you'll like my other Sort videos too! Don't forget to share with your classmates and kindly subscribe ~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@samuraijosh1595]

Hey thanks for the video, quick and to the point with nice visuals but how is space complexity O(log n)???

[@QuocDatPhung]

You're very welcome Doremon! The space complexity depends of where you choose the pivot. I wouldn't worry too much about it. You can find all of my CS videos in this playlist below (don't forget to share and kindly subscribe!): czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@samuraijosh1595]

@@QuocDatPhung never mind I learnt that it was the stack space, log n function calls in the stack. Since quick sort is hyped up as in place sorting, I just assume constant space. Tbf, I've seen leetcode questions where it was advised to just ignore the recursion function stack space and treat the whole thing as if it was constant space. A bit inconsistent...

[@QuocDatPhung]

@@samuraijosh1595 Thanks for letting me know!

[@naza2105]

trank you so much

[@QuocDatPhung]

You're welcome Naza! Please kindly subscribe if you enjoyed! Also, you can find all of my Algorithms videos here: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@samirpandit8899]

the goattt

[@QuocDatPhung]

Thank you SamirPandit! Please kindly share with your friends and subscribe to support me (it means a lot) ~ you can find all of my CS videos in this link: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@coryanders6328]

easily the best video i've seen on this. all the other ones give very poor, if any, explanation as to what they are doing

[@QuocDatPhung]

Thanks so much Coryanders! You'll probably like my 3min Merge Sort video as well: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@TungNguyen-oi4xo]

cảm ơn e, giảng rất dễ hiểu

[@QuocDatPhung]

Cám ơn anh! Em có làm clip về Merge Sort và các algorithms khác ở đây nè: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@yaelw5986]

does this method use hoare's partitioning

[@QuocDatPhung]

No I don't think so. I hope you enjoy this video! If you do, you might also like my Merge Sort video too: czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@thuhuynh7474]

Anh nhìn xịn quáaaa

[@QuocDatPhung]

Hehe cám ơn em! Tất cả clip máy tính của anh nằm trong link sau đây (em đừng quên chia sẻ và đăng kí ủng hộ anh nhé!): czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html

[@hasanshahriarboni7957]

❤

[@QuocDatPhung]

Thanks very much Hasan! I hope you will also enjoy my Merge Sort video: czcams.com/video/ho05egqcPl4/video.html

[@prashantnegi6831]

can anybody reply with python code for this?

[@prashantnegi6831]

don't worry, wrote it in java with the help from your python code, thanks

[@QuocDatPhung]

You're very welcome! You can find all of my CS videos in the link below (don't forget to share with your classmates!): czcams.com/play/PLeTO6OT3-FKmuxOu4RtupTay1yrMp6QGC.html