[masukomi]

> But if people practiced them more, they would realized that there is only 10-20 questions that you can be asked, and everything else is just some minor variation of the most common questions, and you don't specialized training to do project Euler or glassdoor.com questions.

My gut reaction to this is that you're not asking very good questions if it's such simple variations. Unless you're being excessively reductive in that all of programming can be done in just a handful of compiler operations, and thus only a handful of programming questions could be asked.