Warning: Nerdy Post. So when interviewing engineering candidates, we often ask abstract questions. While some people try to gage intelligence and knowledge with these questions, I usually try to gage caution and ability to track down appropriate information and boundaries, as well as the ability to devise a solution. I dont pretend that there is 1 optimal solution by which all candidates are measured, but instead try to get an insight into how they think. Here is my latest question. A 5 story building has 2 elevators. They are already programmed to open, close, and go to the right floor, but we want you to optimize them. How would you do this? I encourage you to ask questions and determine the scope of the project, and then design a solution. Often a candidate will immediately propose a solution based on their own assumptions. Theyll assume there is 1 elevator shaft and that optimization means throughput of people, and theyll suggest having 1 elevator default to floor 2 and the other to floor 4 so they can service any floor with only 1 move. While it can be useful to see their ability to devise a solution given their assumptions, the large number of assumptions is worrisome. Rarely are you handed a fully-formed specification and told to implement it. Usually tasks come in the form of half-baked phrases from management that are focused on 1 subset of users. As an Engineer, I need to know that you wont take that poorly formed request and run with it as-is. You have to demonstrate that you can flesh out a problem and determine the best scope to solve the real problem, rather than chasing after every goose-chase management invariably sends you on. Rather than prod for responses in this thread, Ill highlight some of the gotchas here. 1) What does optimization mean? Do you want the highest pedestrian throughput? Do you want the lowest elevator mileage? Is upward traffic as important as downward? etc... 2) Do both elevators service all floors? Is 1 an express elevator? Does 1 only go from the entry floor to the first floor where a security check exists? etc... 3) Where are the elevators? Are they side-by-side? Are they at opposite ends of the building? 4) Are the elevators functionally identical? Is one a freight elevator? Does one have a larger weight capacity? Does 1 have larger dimensions that can accommodate for wheel chairs? etc... 5) Do all pedestrians have access to all floors? Are there any security constraints? ...there is an infinite set of questions you could ask, and I wont judge a candidate on whether or not they asked the set I came up with. Often I will rank a candidate higher if they are able to devise valid concerns I ignored (as that candidate thinks differently than I do, so they will likely complement my views and avoid the same pitfalls and blind-spots I would fall into). Maybe Im a sadist, but I really enjoy interviewing candidates. Its a rare opportunity to be allowed to prod at someones brain and see how they think. Thoughts? Additional elevator-scope questions? Better solutions for identical elevators side-by-side?
Posted on: Tue, 30 Sep 2014 18:00:28 +0000
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