Once I was sent a codility test that required me to develop a FULLY TESTED, CORRECT, COMPILED and RUNNABLE 100 LoCs solution in 60 minutes. The problem statement was pretty long, difficult to understand and with misleading examples. I never got to finish it.

Then I started browsing the different codility “lessons” and most of them were poorly written, with unclear boundaries and were tested with arbitrary tests that violated the problem rules they had given previously as part of the problem statement.

Then, sometimes they expect the solution to be efficient and use an arbitrary number of milliseconds as a run time threshold. But they never state that threshold as part of the problem. They just say it must be “efficient”. They don’t mention how many ram you have available, so you wouldn’t know if you can memoize and to what extent.

Coding rank sites are just BS