Have you guys ever encountered incompetent interviewers who cannot understand their own interview questions? I recently interviewed with Apple. The question is like this: given a list of events 1 to n. Each event i has a probability P_i. And they asked me to find a subset of events with weight constraint to maximize the probability of the combined event. Of course I don’t know how to solve it without knowing the properties of these events. Then I asked the interviewer if the events are independent. The interviewer was just confused and don’t know what “independent” means. Then I asked if we can add the probabilities. (It works for exclusive events and usually a good approximation.) Then the interviewer got mad immediately and accused me how I can add probabilities because the sum may be larger than 1. He even accused me if I know probability theory at all. (I got A+ for my probability class from MIT by the way) Now without any useful input, I try to solve the problem to maximize the probability for the worst case scenario. The solution is to pick the events with largest probability greedily. The he got mad again and ask me why I can chose a event with 0.91 probably over two events with 0.9 probability. In the end, I think he assumes the events are independent without knowing what independence is. I provided a correct solution for independent events in the last 3 minutes or so but I still got rejected. Has anyone encountered incompetent interviewers like this? How do you deal with them? I feel I don’t want to work with this kind of people anyway. But I am still upset especially because I was accused by someone who don’t know what independent events are.
which country was he from? india or china ?
He is white and speaks American English.
You got off easy. Imagine working with him.
Don't worry, you should have rejected him first. More power to you
Sorry about your experience. Still don’t understand the qs. Glad I did not encounter this qs during my interview.
Was this on the macbook team? I had an interviewer first give me a problem I had known to never before been solved, and then he asked me a problem with which his answer was incorrect.
This sounds like a variant if coin change DP problem. Anyway yea we all have bad interview experiences. Can't do much tho.
Yup. If the events are exclusive, it’s a regular knapsack problem. If they are independent, you need to do some math and you can transform it into a knapsack problem. If we don’t know anything about the problem, we should use greedy algorithm and pick the ones with highest probability.
wtf ru guys talking about?
I don't have much experience in this but last September I had an interview with Google where the interviewer didn't say a thing. All of their recruitement videos / events say that the interviewer will step in if you speak and say your thought process while you code. My first solution was wrong and instead of pointing that out he asked the follow up question which led me to spend the whole interview building on something wrong and even said that I did well and demonstrated that I could solve the problem. I realized my mistake right after the interview and as I expected I got a rejection. I know it's not his fault that I miscalculated but had he just said something I could've fixed it
I think in your case the interviewer may not even know you were wrong at the time. I have been rejected by Facebook because my algorithm is correct but different from the standard solution and the interviewer struggled to understand. I have to spend the whole time teaching the interviewer and end up having no time for follow-ups.
Shouldn’t you have demanded that if there is no information regarding the independence of events then the question is incomplete. It becomes a pissing contest and him not knowing independence means that he doesn’t know probability. You should have given him P(A|B) classic equation as a litmus test.
Apple usually drags whatever available engineer into interviews. We do not have a formal interview training program. So unfortunately you might get a bad interviewer from time to time. Sorry to hear about your experience. Be sure to tell the recruiter and maybe they can take that individual off the rotation.
You sound like an equally terrible interviewee based on how bitter you are.
not really
I tried my best to ask questions and get information needed to solve the problem. When I finally understood that he just secretly assumed that those are independent events, I provided at least the outline of the correct algorithm. I don’t see any way I can do better except that I happened to make the same assumption with the interviewer.