Comment by LanceH | Hacker News Reader

Comment by LanceH | Hacker News Reader

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I was asked a puzzle question that I hadn't heard before. I answered it directly almost immediately. In a later interview with the CEO he asked if I had heard the problem before because the interviewers were sure I had with such a fast answer. I said I had not and just left it at that. Playing the whole thing back in my head, I think this cost me the job for "lying" to them. I might have been able to convince them on how quickly I got the problem if I had taken this as a questioning of my integrity.

"There are 128 chairs on a ski lift. You get on at the bottom, and ride it all the way to the top. On your trip up, how many do you pass on their way down?"

There may have been some distracting info of distances and speeds in there to make get you going in the wrong direction.

My experience with puzzlers is that average people like to feel superior for knowing the answers to a puzzle that someone else doesn't know. The people who can solve these easily are thrilled to find a puzzle they don't know the answer to. Then there is the group who can make a good puzzle.

Something like happened to me once, someone asked me a riddle (it was: "you have a polynom of coefficients that are positive integers. I can give you the values of this polynom at integer points of your choice. Can you get all the coefficients by asking only two values?"). Somehow I got it very quickly, and was thinking in my head "oh man I didn't know I was that clever", but the guy thought I already knew the answer.

I have said 72 assuming constant speed and equidistant spacing of the chairs- though as that seems to easy

Wouldn't the answer be 127 of them? You're passing the one behind you as you get on at the bottom, and the one in front of you as you get on at the top.

I well my view if you walk to the base of the lift half on the chairs are on the up side leg half on the down you get on the one right at the bottom. so you pass all the chairs on the downward leg

Actually this is a simplification as the chairs slow down and bunch up at the bottom and top to make getting on and of simpler

> Actually this is a simplification as the chairs slow down and bunch up at the bottom and top to make getting on and of simpler

Yeah, this is the problem with the question that I noticed as well.

If you don't know what a ski lift is (grew up in the south and didn't have money for vacations as a kid), you might not even know how ski lifts work. In which case maybe you guess that the chairs are fixed and give the 127 answer. Ironically, you guessed wrong and got the correct answer.

If you do know how ski lifts work and assume the interview does as well, then you just look like an idiot.

I guess the lesson is to state all your assumptions (and also, don't ask these questions).

I think I just had an "A-Ha" moment. It took me about 5 seconds to think it through. Good question.

Disagree: it's a terrible question. The answer (all of them) is something you either see or don't, and neither tells you much more than one bit of information about the candidate.

I don't think he meant in terms of an interview question, just a good puzzle.

I'm not convinced; it at least tells you if the interviewee will rush to an answer that appears correct and say "All of them", or if they'll consider it a little more carefully and say "The rest of them". Or if they'll ask for a strict definition of what it means to pass a chair on the way up, to clarify whether or not you count the chair that you're riding on as one that you pass.

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