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Entry tags:
Puzzles, interivews
Now every technical interview involves a whiteboard/computer coding/solving of simple/medium level puzzles. As any sport, one needs recent practice to perform well. I did not practice in that since 1998, and I only had one such interview in ~2010 with google, where I failed.
I don't argue that it is not a worst proxy for evaluating programmer's job performance (in the same way as running speed/stamina is a proxy for evaluating football player skills).
I decided to spend some time to understand my current status and improve it a little bit. So I selected a random puzzle from hackerrank with medium rating and low average pass count.
It took me about 3 hours in total to come up with a correct O square algorithm, and one hour to implement.
This Clojure implementation by the way is probably not O square as it times out on bigger tests. So I need either to profile it and fix, or re-write in C where reasoning about execution time is trivial.
So if I got this puzzle at a Google/Facebook/whatever interview, I would have failed, as one needs to solve this in 30 minutes, not 4 hours. And when I encounter puzzles of similar complexity at work (not very frequently, maybe once every couple of months), solving it in 4 hours is never an issue.
Upd:
For two people, who are much brighter than me, it took several minutes to find the algorithm which is O(n) and describe in the comments. I implemented it (took me half an hour), and now it passes all hackerrank tests:
I don't argue that it is not a worst proxy for evaluating programmer's job performance (in the same way as running speed/stamina is a proxy for evaluating football player skills).
I decided to spend some time to understand my current status and improve it a little bit. So I selected a random puzzle from hackerrank with medium rating and low average pass count.
It took me about 3 hours in total to come up with a correct O square algorithm, and one hour to implement.
This Clojure implementation by the way is probably not O square as it times out on bigger tests. So I need either to profile it and fix, or re-write in C where reasoning about execution time is trivial.
So if I got this puzzle at a Google/Facebook/whatever interview, I would have failed, as one needs to solve this in 30 minutes, not 4 hours. And when I encounter puzzles of similar complexity at work (not very frequently, maybe once every couple of months), solving it in 4 hours is never an issue.
Upd:
For two people, who are much brighter than me, it took several minutes to find the algorithm which is O(n) and describe in the comments. I implemented it (took me half an hour), and now it passes all hackerrank tests:
no subject
For CCD, simple puzzles will suffice, and Google et al are using medium - like this one.
As for abstractions - I think discussing /reasoning about implementation details of database/OS kernel/CPU pipeline/CPU caches/IP routing/switching/filtering (depending on a job area) usually provide a clue. But that would be difficult to quantify, unlike puzzles.