The Quicksort Sorting Algorithm: Pick A Pivot, Partition, & Recurse
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- Опубликовано: 25 мар 2019
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Question: Implement QuickSort. Explain how it works. Explain the best and worst cases.
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This guy's : is this ever impacting u?
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Table of Contents:
Talking About Stuff 0:00 - 1:05
Introducing Quicksort 1:05 - 2:04
The Split Subroutine 2:04 - 2:43
The Partition Subroutine 2:43 - 3:24
Partitioning: Choosing A Bad Pivot 3:24 - 10:34
Partitioning: Choosing A Good Pivot 10:34 - 15:11
Analysis: Choosing Bad Pivots 15:11 - 19:06
Analysis: Choosing Good Pivots 19:06 - 22:07
Analysis: Good Pivots - Work Done At Leaf Level 22:07 - 23:37
Flashback To Merge Sort 23:37 - 24:01
Why Quicksort Is O(n*log(n)) 24:01 - 25:02
Wrap Up 25:02 - 26:12
Errors:
3:25 - 15:11 -> I messed up how I advanced 'i' in both examples. I should have started 'i' at left - 1 everytime...my bad. What should happen is that we should start 'i' at 'left - 1' and anytime we swap into 'i' we always advance 'i' FIRST before the swap. These errors don't change the fundamental job of 'i', which is to keep the tail of the section of items less than the pivot. Make sure you take that away from this.
4:02 -> Forgot to edit that text out haha
24:23 -> This is only the exact bound on the best case. Not the average case as well.
The code for quicksort is in the description. Fully commented for teaching purposes.
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You're one of the most eloquent tech guys on youtube. I just started programming this month, and your video helped me implement quicksort in JS!
great! but im not a tech guy, Im just a guy
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FINALLY someone who explains what a pivot is. Pivot concept is key to understand how quicksort works and also to understand "the kth largest element in an array" problem.
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"We do not place an item, into the section, that is less than the pivot." - just needed that much.
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Continue! You are doing great, man! Thanks a lot!
I have never commented on a RUclips video before but thank you so much for this! Your code for Quicksort actually makes sense, which is something I have not found to be the case for other sources, including Cracking the Coding Interview. I have subscribed :)
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I haven't understood quicksort for 2 years, thanks a bunch man
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Finally understand quick sort! Thanks so much
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probably the most easy to understand video on quicksort. Thank you
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This is the only vedio I found which tells exactly what exactly is PIVOT.. THANKS
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Thank you. Amazing video :)
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Thanks for this, I was actually wondering couple days ago why there isn't a sorting video for quick sort.
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and please recommend us to your family and friends 😀
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Really thanks for the detailed explanation, this video solved my questions watching Wiki of Quicksort
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