From: Brian Adkins <lojicdotcom@...>
Date: 2008-11-07T17:28:09+09:00
Subject: Re: Finding gaps in a sorted sequence

Martin DeMello <martindemello@gmail.com> writes:

> On Thu, Nov 6, 2008 at 9:39 AM, Pete Hodgson <phodgson@lyris.com> wrote:
>> Hi Folks,
>>
>> Given a sorted enumeration I need to find the first gap in a sequence.
>>
>> e.g.
>> 3 == find_gap [1,2,4,5]
>> nil == find_gap [1,2,3,4]
>
> irb(main):001:0> g = [1,2,3,5,6,8,9,10]
> => [1, 2, 3, 5, 6, 8, 9, 10]
>
> irb(main):002:0> gap = g.inject {|a, e| e == a.next ? e : (break a.next)}
> => 4

Beautiful. Excellent use of inject :) I would've thought this would be
better performing also, but it lags the 'each' version by quite a bit:

           user     system      total        real
OP     3.490000   1.240000   4.730000 (  4.755358)
Brian  2.170000   0.830000   3.000000 (  3.000508)
Martin  3.320000   1.240000   4.560000 (  4.582286)

I still think I like it best though because it seems to be the most
natural Ruby solution to the original problem.

-- 
Brian Adkins
http://www.lojic.com/
http://lojic.com/blog/