> "Writing a hash table from scratch" is a programming 101 problem just slightly harder than FizzBuzz, but not by much.

No, it's bloody not.

What's your hash function? Why? What do you do on hash collisions. How many buckets and how big? Does your hash function map to identity or not? Do you exclude certain fields from hashing? How do you handle contention from multiple threads? I can go on and on.

The fact that you think writing a hash is easy betrays a stunning amount of ignorance.

To be fair, the interview question a few posts up mentioned a working hash table, saying nothing about efficiency or thread safety. (though such a question could be gamed with a linked list as a "well akshuolly" a single-bucket hash table...)

That's the difference between a hashtable you might want to use in practice and a toy example to have someone write some code while quizzing some CS theory.