MoveSelector: add another heuristic

game/move_selector.cpp

@@ -18,10 +18,13 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  *****************************************************************************/
 
+#include <boost/foreach.hpp>
+
 #include "move_selector.h"
 #include "round.h"
 #include "results.h"
 #include "bag.h"
+#include "rack.h"
 
 #include "dic.h"
 #include "debug.h"
@@ -30,11 +33,16 @@
 INIT_LOGGER(game, MoveSelector);
 
 #define PLAYED_JOKER (-1000)
+#define LETTER_REPEATED_3_TIMES (-3)
+#define LETTER_REPEATED_4_TIMES (-12)
+#define LETTER_REPEATED_5_TIMES (-40)
+#define LETTER_REPEATED_6_TIMES (-100)
 #define EXTENSION_1 50
 
 
-MoveSelector::MoveSelector(const Bag &iBag, const Dictionary &iDic)
+MoveSelector::MoveSelector(const Bag &iBag, const Dictionary &iDic,
-    : m_bag(iBag), m_dic(iDic)
+                           const Board &iBoard, const Rack &iRack)
+    : m_bag(iBag), m_dic(iDic), m_board(iBoard), m_rack(iRack)
 {
 }
 
@@ -69,6 +77,7 @@ int MoveSelector::evalScore(const Round &iRound) const
 {
     int score = 0;
     score += evalForJokersInRack(iRound);
+    score += evalForRemainingLetters(iRound);
     // Deactivated for now, as it breaks a few non-regression tests,
     // and I don't have time to fix them at the moment... :)
 #if 0
@@ -85,6 +94,42 @@ int MoveSelector::evalForJokersInRack(const Round &iRound) const
 }
 
 
+int MoveSelector::evalForRemainingLetters(const Round &iRound) const
+{
+    // Compute the rack remaining after playing the round
+    Rack remaining = m_rack;
+    for (unsigned i = 0; i < iRound.getWordLen(); ++i)
+    {
+        if (iRound.isPlayedFromRack(i))
+        {
+            remaining.remove(iRound.isJoker(i) ? Tile::Joker() : iRound.getTile(i));
+        }
+    }
+
+    // If a letter is present at least 3 times in the rack, consider it bad
+    // Note: the repetitions are only relevant if the rack is not rejected for
+    // lack of vowels and/or consonants...
+    int score = 0;
+    BOOST_FOREACH(const Tile &t, m_dic.getAllTiles())
+    {
+        const int count = remaining.count(t);
+        if (count >= 3)
+        {
+            if (count == 3)
+                score += LETTER_REPEATED_3_TIMES;
+            else if (count == 4)
+                score += LETTER_REPEATED_4_TIMES;
+            else if (count == 5)
+                score += LETTER_REPEATED_5_TIMES;
+            else if (count == 6)
+                score += LETTER_REPEATED_6_TIMES;
+        }
+    }
+
+    return score;
+}
+
+
 int MoveSelector::evalForExtensions(const Round &iRound) const
 {
     // Find front and back extensions to the given round

game/move_selector.h

@@ -27,6 +27,8 @@ class Round;
 class BestResults;
 class Bag;
 class Dictionary;
+class Board;
+class Rack;
 
 
 /**
@@ -40,7 +42,8 @@ class MoveSelector
     DEFINE_LOGGER();
 public:
 
-    MoveSelector(const Bag &iBag, const Dictionary &iDic);
+    MoveSelector(const Bag &iBag, const Dictionary &iDic,
+                 const Board &iBoard, const Rack &iRack);
 
     /**
      * Return a move to be used as "master move" in a duplicate game.
@@ -58,9 +61,12 @@ public:
 private:
     const Bag &m_bag;
     const Dictionary &m_dic;
+    const Board &m_board;
+    const Rack &m_rack;
 
     int evalScore(const Round &iRound) const;
     int evalForJokersInRack(const Round &iRound) const;
+    int evalForRemainingLetters(const Round &iRound) const;
     int evalForExtensions(const Round &iRound) const;
 
 };

game/results.cpp

@@ -326,7 +326,7 @@ void MasterResults::search(const Dictionary &iDic, const Board &iBoard,
         return;
 
     // Find the best round, according to the heuristics in MoveSelector
-    MoveSelector selector(m_bag, iDic);
+    MoveSelector selector(m_bag, iDic, iBoard, iRack);
     const Round &round = selector.selectMaster(m_bestResults);
     m_rounds.push_back(round);
 }