Comments on: Google Interview Question: Product of other Elements in an Array in O(n)

By: claudio

claudio — Thu, 25 Jun 2009 07:01:22 +0000

@jhon: your interview reports are very interesting, thanks!

By: jhon

jhon — Thu, 25 Jun 2009 06:30:32 +0000

Hi,
I interviewed for the associate product manager position at google, you can read it up here

http://ferozeh.com/Interviews/Google/google.php

By: Problem with an interesting little problem « Antimatroid’s Weblog

Problem with an interesting little problem « Antimatroid’s Weblog — Fri, 08 Aug 2008 01:18:57 +0000

[...] fsharp.it posted the above simple Google interview question on their site a few weeks ago and subsequently the problem was referenced by OJ’s rants and later posted to the programming subreddit on reddit.com. Like everyone else, I sat down and wrote some quick code to solve the problem. After looking a the solution, it seemed to me that this was a rather poorly conceived problem- if not contrived at heart. It doen’t ring to the tune of scalability, performance and quality that one thinks of when the word Google is thrown into the mix. [...]

By: claudio

claudio — Fri, 11 Jul 2008 15:11:39 +0000

Hi Pavel,
we should check how the concatenation operator @ is implemented, I’m not sure its complexity is O(n).
BTW, your solution is very good!

By: Pavel

Pavel — Fri, 11 Jul 2008 14:30:00 +0000

Hi claudio,

Perhaps I’m wrong, but, IMHO, your solution has O(n^2) or O(n*log(n)) complexity because you use @ operator into recursive function.
@ operator has O(n) complexity itself.

BTW my solution http://fsharpere.blogspot.com/2008/07/google-interview-question.html

By: claudio

claudio — Thu, 26 Jun 2008 22:47:43 +0000

Only 4 lines instead of my 22, that’s a great solution!

By: Jon Harrop

Jon Harrop — Thu, 26 Jun 2008 22:37:37 +0000

As a dynamic programming problem you can solve this for small arrays using naive recursion wrapped in a memoize combinator:

let product (a : _ array) =
    let rec f = memoize(fun (i, di) ->
        if i = a.Length then 1 else f(i+di, di) * a.[i])
    Array.init a.Length (fun i -> f(i-1, -1) * f(i+1, 1))

By: OJ’s rants » An Interesting Little Problem

OJ’s rants » An Interesting Little Problem — Sat, 14 Jun 2008 10:40:02 +0000

[...] post was inspired by a recent interview question that was posted over at fsharp.it. It’s one of those neat little questions which looks really simple on the surface but is [...]

By: claudio

claudio — Tue, 10 Jun 2008 18:43:50 +0000

I’m glad to hear that, in my opinion a good mix of problem solving and coding questions is the best way to interview people for software development positions.

By: a.

a. — Tue, 10 Jun 2008 18:37:43 +0000

Microsoft focus on the same thing, they have problem solving and coding questions. But they start with the logical ones on phone interviews.