From: dblack@...
Date: 2006-09-25T01:15:18+09:00
Subject: Re: Help w/ Codegolf Total Triangles- reading input

Hi --

On Mon, 25 Sep 2006, Devin Mullins wrote:

> Drew Olson wrote:
>> Work backwards row by row. In each row, compare the current element with 
>> the next, and whichever ever is larger, add this number to the element in 
>> the same index in the next highest row. Eventually, the value in a[0][0] 
>> will be the largest path...does this makes sense? Is it an effective 
>> strategy?
> Yeah, that does seem like it'll work. I never thought of it that way.
>
> Think of the forwards algorithm, too. Then determine if the code you write 
> with the backwards is 8 bytes shorter (to make up for reverse_each vs each). 
> (I'll have to look at it, myself. :P)
>
> One more hint: You probably don't need to waste your time with map. Consider:
>  a=readlines.each{|i|i.split(" ").each{|j|j=j.to_i}}

That just assigns the lines you've read in, unchanged, to a.  In the
outer each, you split lines and send the results, before you discard
them, to the inner each -- where you reuse the identifier j, and then
throw its new value away.  Meanwhile, all a cares about is the return
value of readlines.each, which is its receiver.

I think maybe map is indeed called for :-)


David

-- 
                   David A. Black | dblack@wobblini.net
Author of "Ruby for Rails"   [1] | Ruby/Rails training & consultancy [3]
DABlog (DAB's Weblog)        [2] | Co-director, Ruby Central, Inc.   [4]
[1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com
[2] http://dablog.rubypal.com    | [4] http://www.rubycentral.org