Hah I feel you there. Around 2 years ago I did a take home assignment for a hiring manager (scientist) for Merck. The part B of the assignment was to decode binary data and there were 3 challenges: easy, medium and hard.

I spent around 40 hours of time and during my second interview, the manager didn't like my answer about how I would design the UI so he quickly wished me luck and ended the call. The first interview went really well.

For a couple of months, I kept asking the recruiter if anyone successfully solved the coding challenge and he said nobody did except me.

Out of respect, I posted the challenge and the solution on my github after waiting one year.

Part 2 is the challenging part; it's mostly a problem solving thing and less of a coding problem: https://github.com/jonnycoder1/merck_coding_challenge