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Even a seasoned expert who literally writes card shuffling software would have a difficult time writing a well-explained solution on a whiteboard in 30 minutes.

by mlthoughts2018 8y ago

Even a seasoned expert who literally writes card shuffling software would have a difficult time writing a well-explained solution on a whiteboard in 30 minutes. Most candidates we interview have a combination of CS degrees, statistics degrees or experience, and are prepped ahead of time with some materials about the general type of question we might ask, and around 90% of them are rejected for failing to solve this question. Around 50% are given extremely poor ratings, like not even getting any type of coherent solution, even inefficient and not handling corner cases. This is what I mean about myopia. 30 minutes is barely enough time for anyone to sketch a solution to any algorithmic problem, even if they are experienced and fully comfortable with the question’s subject matter. This process just filters out candidates who are perfectly capable of solving the problem as a form of severe risk aversion against possibly hiring someone who lacks sufficient technical skills.

stcredzero 8y ago
Even a seasoned expert who literally writes card shuffling software would have a difficult time writing a well-explained solution on a whiteboard in 30 minutes. Sure. We used to give an hour, and HR reduced it to 45 minutes. I'd rather have more time. Also, you can dial up the stringency of this particular question to an expert level where hours could be used. Or, as you admit below, it can be dialed down considerably. Around 50% are given extremely poor ratings, like not even getting any type of coherent solution, even inefficient and not handling corner cases. You could also dial it back to where you accept a coherent, inefficient solution that at least shows an awareness of corner cases. This process just filters out candidates who are perfectly capable of solving the problem as a form of severe risk aversion against possibly hiring someone who lacks sufficient technical skills. So "myopia" in your view is the delusion that such a practice is anything more than that? There are plenty of people in our industry who know that's what it's really for and who know how bad whiteboard interviews are at this task. That doesn't mean the goal is worthless. It seems that many want the goalposts lowered, such that actually understanding anything isn't required anymore. We know the test is bad and that something better should be developed. What I'm arguing against is lowering the standards and getting rid of the test altogether.
- mixmastamyk 8y ago
  > understanding anything isn't required Things are truly understood in solitude not with a gun to your head. Also, what a developer knows this second has less bearing on what they could learn than often thought. No one knows everything.
  - stcredzero 8y ago
    No one knows everything. You should at least know the basics and be able to apply them. I'm rather shocked by the number of 3.75, 4.0 students from good schools who can spout 1st principles, then utterly fail at applying them.
    - mixmastamyk 8y ago
      You’re shocked but have no insight that you might be contributing to the problem.
- AlexCoventry 8y ago
  I think you guys might be talking past each other a bit. A good candidate should be able to O(n log n) time pretty easily, but getting O(n) off the bat would suggest prior knowledge of the problem.

stcredzero 8y ago

Even a seasoned expert who literally writes card shuffling software would have a difficult time writing a well-explained solution on a whiteboard in 30 minutes. Sure. We used to give an hour, and HR reduced it to 45 minutes. I'd rather have more time. Also, you can dial up the stringency of this particular question to an expert level where hours could be used. Or, as you admit below, it can be dialed down considerably. Around 50% are given extremely poor ratings, like not even getting any type of coherent solution, even inefficient and not handling corner cases. You could also dial it back to where you accept a coherent, inefficient solution that at least shows an awareness of corner cases. This process just filters out candidates who are perfectly capable of solving the problem as a form of severe risk aversion against possibly hiring someone who lacks sufficient technical skills. So "myopia" in your view is the delusion that such a practice is anything more than that? There are plenty of people in our industry who know that's what it's really for and who know how bad whiteboard interviews are at this task. That doesn't mean the goal is worthless. It seems that many want the goalposts lowered, such that actually understanding anything isn't required anymore. We know the test is bad and that something better should be developed. What I'm arguing against is lowering the standards and getting rid of the test altogether.

mixmastamyk 8y ago
> understanding anything isn't required Things are truly understood in solitude not with a gun to your head. Also, what a developer knows this second has less bearing on what they could learn than often thought. No one knows everything.
- stcredzero 8y ago
  No one knows everything. You should at least know the basics and be able to apply them. I'm rather shocked by the number of 3.75, 4.0 students from good schools who can spout 1st principles, then utterly fail at applying them.
  - mixmastamyk 8y ago
    You’re shocked but have no insight that you might be contributing to the problem.
AlexCoventry 8y ago
I think you guys might be talking past each other a bit. A good candidate should be able to O(n log n) time pretty easily, but getting O(n) off the bat would suggest prior knowledge of the problem.