That changes everything. It's not a real test at all. There is a broad range of exercises, a lot of which are for coding competition, way too long and too diff

That changes everything. It's not a real test at all. There is a broad range of exercises, a lot of which are for coding competition, way too long and too difficult for a short screening test. I'd advise you to keep the majority of the exercises dead simple. An exercise to print numbers from 1 to 100 will tell you a lot about the candidate. An 1h dynamic programming exercise will stay unanswered most of the time, that doesn't tell you anything useful.