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by jpatokal 3708 days ago
No, it's not a test of whether you know it, it's a test of whether you can implement it. If the candidate doesn't know/recall what BFS is, it's trivial to demonstrate the basic idea on a whiteboard, and it's the candidate's job to convert the idea into code. (Which, at the end of day, is pretty much what the vast majority of coding is about.)
2 comments
ams6110 3708 days ago
It's still not realistic. People don't code on whiteboards. You code (today) with all the resources of the internet at your fingertips, and if you need to invert a binary tree you will use a well-tested implementation from a standard library.
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TheCoelacanth 3708 days ago
It's not supposed to realistic. It's supposed to be a test of programming ability that fits into an hour interview with time left over for talking about other things. Real world projects last months or years. You can't fit that into an hour, so you have to make do with something that can.
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LamaOfRuin 3708 days ago
Which is why they're not asking you to do it in an actual job. It's a proxy problem that is easy to communicate so you're not spending the entire interview explaining the problem. Arguably, fleshing out a spec would also be a valuable test, but not the same one.
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kuschku 3708 days ago
People often do code on Whiteboards – but not actual code, but diagrams, plans, etc.
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catnaroek 3708 days ago
Sometimes actual code too. For instance, if I'm designing an optimization pass for a compiler, I'll write toy IR programs and show how the optimization pass will rewrite them. And I'll do it on a whiteboard.
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kuschku 3708 days ago
Yup. But the thing I meant is that you illustrate things, not actually code your application code.
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catnaroek 3708 days ago
I know for damn sure that, if I'm implementing something algorithmically tricky (not BFS, though), I first sketch the details on a whiteboard or a piece of paper.
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stegosaurus 3708 days ago
I edited my post. Yes, this makes sense, if the interviewer describes what they're actually after.

I have experienced (on both sides of the table) situations in which it just hasn't happened. 'Can you do X?' 'What is X?' 'Never mind, let's move on'.

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