From: Elliot Temple <curi@...>
Date: 2006-08-16T05:53:49+09:00
Subject: Re: [QUIZ] Newbie doubts about the quiz


On Aug 15, 2006, at 1:49 PM, Marcelo Alvim wrote:

> Hey, People.
>
> I'm a newbie, as the subject implies, and some questions about Ruby
> raised when I was trying to solve this quiz.
>
> I'm not trying to create a very fast solution, I'm only trying to
> learn mor of the language. So I'm trying a simple depth-first search
> approach.
>
> I'm going to have this two-dimensional array representing the board.
> At each place of the board, I'll probably put the number that is
> currently on that place.
>
> The problem, now, is that I chose not to assume the board as a torus,
> but as a flat square. So, I'm doing that simple math going from one
> square to the next: if it's an horizontal move, I add 3  or -3 to X;
> if it's vertical, apply the same to Y; if it's the diagonal, add 2 or
> -2 to both of them. Well, you already know that. Unfortunately, Ruby's
> behavior of wrapping arrays over using their negative indices, which I
> like very much on most cases, is kind of annoying now, since I want to
> invalidate access to negative indices.

one way to do it is take the current position and add/subtract the  
changes, and save that in a variable. don't do an array access yet.  
now you can use some if statements to check the values are OK before  
continuing. that's what i did.

-- Elliot Temple
http://www.curi.us/blog/