Solvings of Spotify Tech Puzzles (check https://www.spotify.com/us/jobs/tech/)
Those are some nice little puzzles to solve if you've got time to kill, or a language to test. To ensure your solutions indeed work as expected, one has to send his program to [email protected].
Don't cheat! Try to actually solve them before having a look at the code!
Each folder has its copypasta of the original problem, in case the page might go down.