There was a highly cited paper published earlier this year in my field which introduced a highly theoretical, non trivial, algorithm that relied on extremely heavy theory. The algorithm was exact (Gave the correct solution) but 3 papers were published later on criticizing that it was highly non practical (Its implementation was a nightmare) and proposed approximation algorithms that were simple to implement.
So over the past year, me and 2 of my friends have been trying to implement the exact algorithm and finally we were able to implement it. The algorithm spans 14 files and is implemented in Python. The running time is acceptable for the input size in my field (takes 3-4 minutes on a modern computer to terminate). We also verified its correctness on a data set and it really did predict the exact solution.
We would love to publish the code, but one of our advisors said that it is unlikely that Code only would be publishable in a reputable journal/conference. One option is that we can just put it on Github but that doesn't really count as a publication. Are there conferences/journals which would take a 1-2 page paper that just describes a hard implementation? The only novel thing we did was that we've had to make very minor changes to the algorithm to make it practical but proved that these minor changes don't change the correctness (just makes implementation a lot easier!).