From: James Koppel <jamesbkoppel@...>
Date: 2007-10-08T08:19:17+09:00
Subject: Re: [QUIZ] Itinerary for a Traveling Salesman (#142)


On Oct 7, 2007, at 12:28 PM, James Edward Gray II wrote:

>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



Yes, thank you. I seem to recall accidentally striking a key with my cursor somewhere in the middle of Ruby code on more than one occasion; I guess that happened, and I failed to notice it.





       
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