Re: Depth First Search of a Char_Matrix?

[Alex <willmann817@gmail.com>]

On Saturday, April 27, 2013 12:51:44 PM UTC-4, Alex wrote:
> On Saturday, April 27, 2013 12:34:55 PM UTC-4, Shark8 wrote:
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> > On Saturday, April 27, 2013 10:27:23 AM UTC-6, Alex wrote:
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> > > On Saturday, April 27, 2013 10:09:10 AM UTC-4, Alex wrote:
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> > > > 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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> > > > BBBWW
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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?
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> > Simple:
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> > 1 )  Add a local variable indicating the color to Is_Alive, that will be accessable to its nested functions.
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> > 2 )  After checking for null on (x,y) assign that to the variable before calling recursion.
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> > You could also make that variable a constant and use a conditional expression [in Ada 2012] to set the initial value -- something like:
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> > 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.
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> Thanks! So I am given the function signature, not really a function body that looks like this
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>    function Count_Alive(Board : Char_Matrix) return Integer is
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>  	M : Char_Matrix := Board;  
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> 	begin
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>       return -999;
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>    end Count_Alive;
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> So I understand much of your logic, but I am given a matrix of characters defined as such:
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> type Char_Matrix is array(Positive range <>, Positive range <>) of Character;
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> So could you give me like an algorithm in words on what I need to do instead of giving me the answer in code?

The characters are just like the original example: either a 'B' a 'W' or a '.'  ('.' is empty space, not null)