alt Hacker NewsI am, thankfully, out of this craziness now but it was fun solving ton of such puzzles from Yashavant Kanetkar books while preparing for campus hiring interviews back in 2000. "Test Your C Skills" in particular. Fun times.
https://www.scribd.com/document/235004757/Test-Your-C-Skills...
"Test Your C Skills" is a published book by Yashavant Kanetkar, apparently published in 2005, and still available in paperback. The document you linked to appears to be a scan of a printed copy of that book, and is almost certainly in violation of copyright. The cover and the title and copyright pages are notably missing.