[iagno] ComputerPlayer: game over should be max alpha/beta

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 769c6cb1576cd707e51278065ca2c9be481d3bd5
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Fri Sep 27 23:20:24 2013 -0500

    ComputerPlayer: game over should be max alpha/beta

 src/computer-player.vala |   22 ++++++++++++++++++++--
 src/game.vala            |    2 +-
 2 files changed, 21 insertions(+), 3 deletions(-)
---
diff --git a/src/computer-player.vala b/src/computer-player.vala
index 32b9df5..bd50c14 100644
--- a/src/computer-player.vala
+++ b/src/computer-player.vala
@@ -95,7 +95,7 @@ public class ComputerPlayer : Object
     private static int search (Game g, Strategy strategy, int depth, int a, int b, int p, ref int move_x, 
ref int move_y)
     {
         /* If the end of the search depth or end of the game calculate how good a result this is */
-        if (depth == 0 || g.is_complete ())
+        if (depth == 0)
             return calculate_heuristic (g, strategy);
 
         /* Find all possible moves and sort from most new tiles to least new tiles */
@@ -105,12 +105,30 @@ public class ComputerPlayer : Object
             for (var y = 0; y < 8; y++)
             {
                 var n_tiles = g.place_tile (x, y);
-                if (n_tiles > 0)
+
+                if (g.is_complete ())
+                {
+                    move_x = x;
+                    move_y = y;
+
+                    if (g.count_tiles (g.current_color) > g.count_tiles (Player.flip_color 
(g.current_color)))
+                    {
+                        g.undo ();
+                        return p > 0 ? int.MAX : int.MIN;
+                    }
+                    else
+                    {
+                        g.undo ();
+                        return p > 0 ? int.MIN : int.MAX;
+                    }
+                }
+                else if (n_tiles > 0)
                 {
                     var move = PossibleMove (x, y, n_tiles);
                     moves.insert_sorted (move, compare_move);
                     g.undo ();
                 }
+                /* Do not undo if place_tile failed */
             }
         }
 
diff --git a/src/game.vala b/src/game.vala
index 9a8b0e9..f0fa393 100644
--- a/src/game.vala
+++ b/src/game.vala
@@ -190,7 +190,7 @@ public class Game : Object
         return n_flips;
     }
 
-    private int count_tiles (Player color)
+    public int count_tiles (Player color)
     {
         var count = 0;
         for (var x = 0; x < width; x++)