undefined | Better HN

0 pointstwawaaay3y ago0 comments

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).

0 comments

eranation3y ago

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...

twawaaayOP3y ago

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.

Izkata3y ago

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...

yannickmoy3y ago

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.

astrange3y ago

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.

j / k navigate · click thread line to collapse