From: James Edward Gray II <james@...>
Date: 2007-10-08T02:28:36+09:00
Subject: Re: [QUIZ] Itinerary for a Traveling Salesman (#142)

On Oct 7, 2007, at 9:20 AM, James Koppel wrote:

> First, before I get to my main solution, I would like to show that,  
> as Morton pointed out, yes, it is very possible to have a quick,  
> exact solution. Here's one that does so for N >= 3 (N=2 and N=1  
> nevertheless draw correctly; a call to uniq would make them work).
>
> require 'RMagick'
> require 'enumerator'
>
> <definitions of Grid and draw_itin removed - see main solution below>
>
> n = ARGV[0].to_i
>
> itin = ([0]*n).zip((0...n).to_a)
>
> 1.step(n-3, 2) do |x|
>   itin += ([x]*(n-1)).zip((1...n).to_a.reverse)
>   itin += ([x+1]*(n-1)).zip((1...n).to_a)
> end
>
> if n%2==0
>   itin += ([n-1]*(n-1)).zip((0...n).to_a.reverse)
> else
>   (n-1)..step(2, -2) do |y|
>     itin += [[n-2,y],[n-1,y],[n-1,y-1],[n-2,y-1]]
>   end
> end
>
> itin += (0...n).to_a.reverse.zip([0]*n)
>
> $grid = Grid.new(n) #Because draw_itin asks for it
> draw_itin(itin, "#{n}x#{n}tour2.jpg")

I believe there's a typo in the above.  Shouldn't it be:

   (n-1).step(2, -2) do |y|  # I removed a .

?

James Edward Gray II