Re: Depth First Search of a Char_Matrix?

[Shark8 <onewingedshark@gmail.com>]

On Saturday, April 27, 2013 10:27:23 AM UTC-6, Alex wrote:
> On Saturday, April 27, 2013 10:09:10 AM UTC-4, Alex wrote:
> 
> > Below is Char_Matrix representation of the board game "Go".  A 'W' represents a white piece, a 'B' represents a black piece, and a '.' represents a empty space.  Each black or white piece can either be alive or dead.  A piece is Alive is if it horizontally or vertically next to a '.' OR if it is horizontally or vertically next to another piece that is alive. You can think of aliveness as being contagious.  How can I use depth first search to count the number of alive black pieces and alive white pieces?  
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> > WW.BB
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> > .WWWW
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> > WWBBB
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> > 
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> > BBBWW
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> > 
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> > WWBW.
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> > In this example there are 11 alive white piece and 2 alive black pieces.
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> > Can anyone provide any insight into this problem?
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> 
> 
> Shark you are correct,  I forgot to include the fact that only like colors are contagious.  Thank you very much for your assistance.  Without providing the code how would I change it to reflect this piece of missing logic?

Simple:
1 )  Add a local variable indicating the color to Is_Alive, that will be accessable to its nested functions.
2 )  After checking for null on (x,y) assign that to the variable before calling recursion.

You could also make that variable a constant and use a conditional expression [in Ada 2012] to set the initial value -- something like:
Color : Constant Piece_Color:= (if board(x,y) /= null then board(x,y).color else white); -- DEFAULT to white on NULL, otherwise set to the initial piece's color.