From: James Edward Gray II <james@...>
Date: 2005-12-13T03:44:00+09:00
Subject: Re: Calculating single-digit summands

On Dec 12, 2005, at 11:02 AM, draq wrote:

> This is a newer algorithm which works much more faster.
>
> def sum (arr)
> # sorry James Edward Gray II, but I'm not using an enum.

You don't think so?  Let's ask Ruby...

 >> Array.ancestors.find { |par| par.to_s =~ /enum/i }
=> Enumerable
 >> arr = Array.new
=> []
 >> arr.is_a? Enumerable
=> true
 >> arr.respond_to? :inject
=> true

Ruby thinks so.  Let's try a sum:

 >> arr = (1..10).to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
 >> arr.inject { |sum, n| sum + n }
=> 55

Looks good to me.

>   arri.each do |a|
>     arri.delete_if { |a| sum(a) != number }
>   end

The whole point of delete_if() is that you don't need the each().   
Try taking it out.  ;)

James Edward Gray II