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Comment by dahart | Hacker News Reader

You sure it was this algorithm and not Bubble Sort?

> algorithmic complexity isn’t everything

Yeah very true. Or at least hopefully everyone knows that complexity analysis only applies to large n, and small inputs can change everything. In console video games it was very common to avoid dynamic allocation and to use bubble sort on small arrays. Also extremely common to avoid a sort completely and just do a linear search on the (small) array while querying, that can end up being much faster than sorting and binary searching, especially when the total number of queries or the number of queries per frame is also low.

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Oh yeah, linear search I did a lot to the same consternation of other devs.

The issue was the device was so low in memory (2MB of unified NV and flash for code, files and operating memory) that there simply did not exist enough space for a lot of things to be held to be any problem for the 20MHz ARM7 controller as long as you did not do anything stupid. 600kB of it was used by OpenSSL and further 300kB by operating system anyway (I am aware of how funny it sounds when OpenSSL takes twice as much space as OS).

That is pretty awesome if you came up with this exact algorithm a decade ago, ( it was published in 2021, but apparently was in the wild in 2015[1] and I assume discovered earlier, but no one thought it was interesting enough to publish). Why didn’t you use bubble sort / insertion sort? (The algorithm in the paper looks like bubble sort at first look but is basically a clever insertion sort) what was the benefit of using it this way?

[1] https://cs.stackexchange.com/questions/45348/why-does-this-s...

I am not sure how awesome it is. It looks like something you can stumble on your own by accident on a whiteboard on an interview and use successfully even if you don't know why it works exactly.

Honestly, I always thought it is a common knowledge and it is just too simple and for this reason gets omitted from books.

People in CS/IT tend to not spend a lot of time on algorithms with bad complexity and so I am used to people discounting algorithms with useful properties just because there is another that is a bit more efficient when n goes to infinity.

For a related eye-opening result, with both practical application and interesting research backing it, see this talk on "Quicksorts of the 21st century" at Newton Institute on Verified Software last year: https://www.newton.ac.uk/seminar/30504/

TLDR; practical complexity computation needs to take into account things like memory access latency on different architectures.

Yeah, this sorting algorithm is something you can come up with by accident if you do bubble sort wrong. I wouldn't be surprised if a lot of beginners came up with this one in intro courses. I think I saw it around 2006-2008 when I was a TA and one of my students couldn't figure out why his array got sorted in the wrong order (don't remember for sure though).

For example, from 2016, here's someone not getting the difference between the two: https://stackoverflow.com/questions/40786409/whats-the-diffe...

That’s not surprising, OpenSSL has terrible code quality and besides that was written in the era of thinking you should unroll all your loops so they go faster.

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