Lower Bounds for Comparison Based Sorting: Decision Trees

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  • เผยแพร่เมื่อ 26 พ.ย. 2024

ความคิดเห็น • 15

  • @HA7DN
    @HA7DN 4 ปีที่แล้ว +13

    I always thought this proof was some crazy-math-heavy thing, but you explained this so well that it now seems too simple!

    • @AlgorithmswithAttitude
      @AlgorithmswithAttitude  4 ปีที่แล้ว +3

      Somebody took their clever pills when they came up with that argument. But part of its ingeniousness is that it is easy to understand for the rest of us. This one is simple enough that, if you show students what a decision tree is, you an guide them to discover the rest of the argument on their own.

  • @AK09037
    @AK09037 3 ปีที่แล้ว +1

    I want this channel to blow up. This is the best algorithm channel on youtube

    • @AlgorithmswithAttitude
      @AlgorithmswithAttitude  3 ปีที่แล้ว +4

      It seems like the channel has been around long enough, but it hasn't happened yet, so I don't expect it to happen. But perhaps someday Alan Turing will look down from above and deem it worthy of a larger audience...

  • @davidnguyen9023
    @davidnguyen9023 3 หลายเดือนก่อน

    Thank you, the explanation is great! The only thing I had to find more details on was why lg(n!) = Ω(n lg(n)).

    • @AlgorithmswithAttitude
      @AlgorithmswithAttitude  2 หลายเดือนก่อน +1

      It seems reasonable to not have that analysis be part of this video, but maybe I should link to an explanation. But, because log (product) = sum (log), taking the top half of the factorial terms (each at least n/2), we can see lg n! Is at least (n/2) (lg (n/2)) = (n/2) ((lg n) - 1), where the lower bound is easier to see.

    • @davidnguyen9023
      @davidnguyen9023 2 หลายเดือนก่อน

      @@AlgorithmswithAttitude I see :) In my opinion, if the explanation fits into 1-2 lines, why not include it in the slideshow, since the result may not be clear to everyone? On the other hand, one could also argue that since the proof isn't that hard, it could be left as an exercise.

  • @KoScosss
    @KoScosss 3 ปีที่แล้ว

    Thanks!
    Couldn’t get where 2^h was coming from and why n! ≤ 2^h in my other source of learning algorithms, this video helped 👍

  • @minmyatzawmoe5023
    @minmyatzawmoe5023 2 ปีที่แล้ว

    Mind blown!!! Love it

  • @N-e0N
    @N-e0N 3 ปีที่แล้ว

    Why does the insertion sort for loop start from 1? Because elements in arrays start from index 0..?

    • @AlgorithmswithAttitude
      @AlgorithmswithAttitude  3 ปีที่แล้ว +1

      Yes. The first thing we do is insert the item at index 1 into the (trivially already sorted) list of one item ending (and starting) at index 0.

    • @N-e0N
      @N-e0N 3 ปีที่แล้ว

      @@AlgorithmswithAttitude Got it, thanks!

  • @BullishBuddy
    @BullishBuddy 4 ปีที่แล้ว

    keep up good work!

  • @Daniel-iy1ed
    @Daniel-iy1ed 2 ปีที่แล้ว

    That was perfect

  • @siddharthmagadum16
    @siddharthmagadum16 3 ปีที่แล้ว

    Thanks man