DEV: 3rd assignment draft

src/host/labyrinth/Board.java

@@ -13,7 +13,6 @@
 package host.labyrinth;
 
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.function.IntFunction;
 
 /**
@@ -35,9 +34,10 @@ class Board {
       this.S   = 0;
       this.W   = 0;
       tiles    = null;
-      supplies =null;
+      supplies = null;
       walls    = new ArrayList<Edge>();
-      moves    = new ArrayList<Integer[]>();
+      moves    = new int[Const.numOfPlayers][Player.MOVE_DATA_SIZE];
+      playerCount =0;
    }
 
    /**
@@ -54,7 +54,8 @@ class Board {
       tiles    = new Tile[N*N];
       supplies = new Supply[S];
       walls    = new ArrayList<Edge>();
-      moves    = new ArrayList<Integer[]>();
+      moves    = new int[Const.numOfPlayers][Player.MOVE_DATA_SIZE];
+      playerCount =0;
    }
 
    /**
@@ -72,17 +73,28 @@ class Board {
     */
    Board(Board b) {
       // Copy primitives
-      this.N   = b.N;
-      this.S   = b.S;
-      this.W   = b.W;
-      // Clone arrays
-      this.tiles     = b.tiles.clone();
-      this.supplies  = b.supplies.clone();
+      this.N      = b.N;
+      this.S      = b.S;
+      this.W      = b.W;
+      tiles       = new Tile[b.tiles.length];
+      supplies    = new Supply[b.supplies.length];
+      walls       = new ArrayList<Edge>();
+      moves       = new int[Const.numOfPlayers][Player.MOVE_DATA_SIZE];
+      playerCount =b.playerCount;
+
+      // clone moves array of array of primitives
+      for (int i=0 ; i<b.moves.length ; ++i)
+         this.moves[i] = b.moves[i].clone();
+
+      // Clone arrays of objects
+      for (int i=0 ; i<b.tiles.length ; ++i)
+         this.tiles[i] = new Tile(b.tiles[i]);
+      for (int i=0 ; i<b.supplies.length ; ++i)
+         this.supplies[i] = new Supply(b.supplies[i]);
+
+      // clone vectors
       for (Edge it: b.walls)
-    	  this.walls.add(new Edge(it));
-      for (Integer[] m : b.moves) {
-         this.moves.add(m);
-      }
+        this.walls.add(new Edge(it));
    }
    /** @} */
 
@@ -220,29 +232,34 @@ class Board {
    int size ()    { return N; }
 
    /**
-    * Boards utility to give access to other player moves.
+    * Utility function to create player IDs
+    * @return  The generated player id.
+    */
+   int generatePlayerId () throws Exception {
+      if (playerCount < Const.numOfPlayers)
+         return playerCount++;
+      else
+         throw new Exception("Maximum number of players exceeded");
+   }
+
+   /**
+    * Boards utility to give access to other player Id.
     *
     * @param playerId   The id of player who asks
-    * @return           The moves data of all other players
-    */
-   int[][] getOpponentMoves (int playerId) {
-      int[][] ret = new int[moves.size()-1][Const.moveItems];
-      int ii= 0, ri =0;
-      for (Integer[] m : moves) {
-         if (ii != playerId)
-            ret[ri++] = Arrays.stream(m).mapToInt(i->i).toArray();
-         ++ii;
-      }
-      return ret;
+    * @return           The other player's Id.
+    */
+   int getOpponentId(int playerId) {
+      return Const.numOfPlayers - (playerId +1);
    }
 
    /**
-    * Utility function to create player IDs
-    * @return  The generated player id.
+    * Boards utility to give access to other player moves.
+    *
+    * @param playerId   The id of player who asks
+    * @return           The moves data of other player
     */
-   int generatePlayerId () {
-      moves.add(null);
-      return moves.size() -1;
+   int[] getOpponentMove (int playerId) {
+      return moves[getOpponentId(playerId)];
    }
 
    /**
@@ -256,7 +273,8 @@ class Board {
     * @param playerId   The id of the player who update his/her data.
     */
    void updateMove(int[] m, int playerId) {
-      moves.set(playerId, Arrays.stream(m).boxed().toArray(Integer[]::new));
+      //moves.set(playerId, Arrays.stream(m).boxed().toArray(Integer[]::new));
+      moves[playerId] = m;
    }
 
    /** @} */
@@ -295,7 +313,7 @@ class Board {
     * <a href="https://github.com/sean-parent/sean-parent.github.io/blob/master/better-code/03-data-structures.md"> see also here</a>
     * @return  Reference to inner walls array.
     */
-   ArrayList<Integer[]> getMoves() { return moves; }
+   int[][] getMoves() { return moves; }
 
    void setN(int N)  { this.N = N; }
    void setS(int S)  { this.S = S; }
@@ -326,7 +344,7 @@ class Board {
     * @note    Use with care.
     * Any call to this function will probably add memory for the garbage collector.
     */
-   void setMoves(ArrayList<Integer[]> moves) { this.moves =moves; }
+   void setMoves(int[][] moves) { this.moves =moves; }
 
    /** @} */
 
@@ -633,6 +651,7 @@ class Board {
                                      *  Array to hold all the walls using the edge representation 
                                      *  required by the closed room preventing algorithm. 
                                      */
-   private ArrayList<Integer[]>  moves;
+   private int[][] moves;
+   private int playerCount;
    /** @} */
 }

src/host/labyrinth/Common.java

@@ -19,16 +19,23 @@ import java.util.Collections;
  * Class to hold constant values for entire application
  */
 class Const {
+   static final int numOfPlayers = 2;
    static final int maxTileWalls = 2;  /**< Number of maximum walls for each tile on the board */
    static final int noSupply =-1;      /**< Number to indicate the absent of supply */
    static final int noOpponent =-1;    /**< Number to indicate the absent of supply */
    static final int noTileId =-1;      /**< Number to indicate wrong tileId */
    static final int EOR =-1;           /**< Number to indicate the End Of Range */
-   static final int moveItems =4;      /**< The number of items return by move() */
    static final int viewDistance =3;   /**< The max distance of the Heuristic player's ability to see */
+   static final int noView = viewDistance+1;
 
-   static final double opponentFactor  =1.0;
-   static final double supplyFactor    =0.65;
+   /** Parameters to control move evaluation */
+   /** @{ */
+   static final double opponentFactor  = 1.0;   /**< opponent distance factor */
+   static final double supplyFactor    = 0.65;  /**< supply distance factor */
+   static final double preMoveFactor   = 0.65;  /**< pre move distances factor */
+   static final double postMoveFactor  = 0.35;  /**< post move distances factor */
+   static final int minimaxTreeDepth   = 4;     /**< The maximum depth of the minimax tree */
+   /** @} */
 }
 /**
  * Application wide object to hold settings like values for the session.
@@ -68,13 +75,16 @@ class Direction {
    static final int  RIGHT =3;   /**< East direction */
    static final int  DOWN  =5;   /**< South direction */
    static final int  LEFT  =7;   /**< West direction */
+   static final int  NONE  =8;   /**< No direction */
 
    /**
     * Utility to get the opposite direction.
     * @param direction  Input direction
     * @return           The opposite direction
     */
-   static int opposite (int direction) { return (direction+4)%DirRange.End; }
+   static int opposite (int direction) {
+      return (direction != NONE) ? (direction+4)%DirRange.End : NONE;
+   }
 
    static int get (int fromId, int toId) {
       if      (Position.toID(Position.toRow(fromId),   Position.toCol(fromId)-1) == toId)
@@ -133,6 +143,7 @@ class Position {
          case Direction.DOWN: this.id = toID(row-1, col);   break;
          case Direction.LEFT: this.id = toID(row, col-1);   break;
          case Direction.RIGHT:this.id = toID(row, col+1);   break;
+         case Direction.NONE: this.id = toID(row, col);     break;
       }
    }
 

src/host/labyrinth/Game.java

@@ -18,13 +18,14 @@
  * all the supplies of the board before Minotaur catches him and before the
  * game ends.
  * 
- * In this 2nd assignment we deal with the creation of a new heuristic player
+ * In this 3rd assignment we deal with the creation of a new minimax player
  * who can cheat and manipulate the dice. Documented classes:
  *  - Tile
  *  - Supply
  *  - Board
  *  - Player
  *  - HeuristicPlayer
+ *  - MinMaxPlayer
  *  - Game
  *
  * Which are the requested classes. We also provide some extra functionalities in:
@@ -156,9 +157,9 @@ public class Game {
          // Create a game, a board and 2 players.
          Game game         = new Game();
          Board board       = new Board(Session.boardSize, Session.supplySize);
-         Player T          = new HeuristicPlayer("Theseus", true, board, 0);
+         Player T          = new MinMaxPlayer("Theseus", true, board, 0);
          Player M          = new Player("Minotaur", false, board, Position.toID(Session.boardSize/2, Session.boardSize/2));
-         Player players [] = {T, M};
+         Player players [] = {M, T};
 
          // Populate data to the board
          board.createBoard(T.playerTileId(), M.playerTileId());

src/host/labyrinth/HeuristicPlayer.java

@@ -1,5 +1,5 @@
 /**
- * @file Player.java
+ * @file HeuristicPlayer.java
  *
  * @author
  *    Anastasia Foti AEM:8959
@@ -29,7 +29,7 @@ class HeuristicPlayer extends Player {
     * @param row        The row coordinate of initial player position
     * @param column     The column coordinate of initial player's position
     */
-   public HeuristicPlayer(String name, boolean champion, Board board, int row, int column) {
+   public HeuristicPlayer(String name, boolean champion, Board board, int row, int column) throws Exception {
       super(name, champion, board, row, column);
    }
 
@@ -40,7 +40,7 @@ class HeuristicPlayer extends Player {
     * @param board      Reference to the board of the game
     * @param tileId     The tileId coordinate of player's initial position
     */
-   public HeuristicPlayer(String name, boolean champion, Board board, int tileId) {
+   public HeuristicPlayer(String name, boolean champion, Board board, int tileId) throws Exception {
       super(name, champion, board, tileId);
    }
    /** @} */
@@ -58,7 +58,7 @@ class HeuristicPlayer extends Player {
       Position pos = new Position(Position.toRow(currentPos), Position.toCol(currentPos));
 
       for (int i=0 ; board.isWalkable(pos.getId(), direction) && i<Const.viewDistance ; ++i) {
-         pos = new Position(Position.toRow(pos.getId()), Position.toCol(pos.getId()), direction);
+         pos = new Position(pos.getRow(), pos.getCol(), direction);
          if (board.hasSupply(pos.getId()))
             return i+1;
       }
@@ -73,14 +73,12 @@ class HeuristicPlayer extends Player {
     */
    int opponetInDirection(int currentPos, int direction) {
       Position pos  = new Position(Position.toRow(currentPos), Position.toCol(currentPos));
-      int [][] opps = board.getOpponentMoves(playerId);
+      int [] opp = board.getOpponentMove(playerId);
 
       for (int i=0 ; board.isWalkable(pos.getId(), direction) && i<Const.viewDistance ; ++i) {
-         pos = new Position(Position.toRow(pos.getId()), Position.toCol(pos.getId()), direction);
-         for (int o =0 ; o<opps.length; ++o) {
-            if (opps[o][0] == pos.getId())
-               return i+1;
-         }
+         pos = new Position(pos.getRow(), pos.getCol(), direction);
+         if (opp[MOVE_TILE_ID] == pos.getId())
+            return i+1;
       }
       return Const.noOpponent;
    }
@@ -102,8 +100,15 @@ class HeuristicPlayer extends Player {
            - ((opDist != 0) ? (1.0/opDist  * Const.opponentFactor) : 0); 
    }
 
-   // Must return a new move always
-   int getNextMove(int currentPos) {
+   /**
+    * Selects the best possible move to return
+    * @param   currentPos  Player's current position to the board
+    * @return  The move array
+    *
+    * @note
+    *    This function always return a new move.
+    */
+   int[] getNextMove(int currentPos) {
       Range dirs        = new Range(DirRange.Begin, DirRange.End, DirRange.Step);
       int N             = dirs.size();
       double[] eval     = new double[N];
@@ -127,7 +132,8 @@ class HeuristicPlayer extends Player {
          dir = directionOfMax (eval, eval_dir, N);
       }
       Position new_pos = new Position( Position.toRow(currentPos), Position.toCol(currentPos), dir );
-      return new_pos.getId();
+      int [] ret = {new_pos.getId(), new_pos.getRow(), new_pos.getCol(), dir};
+      return ret;
    }
 
    /**
@@ -144,37 +150,36 @@ class HeuristicPlayer extends Player {
     * <li> int[0]: The tileId of the final player's position.
     * <li> int[1]: The row of the final player's position.
     * <li> int[2]: The column of the final player's position.
-    * <li> int[3]: The supplyId in case player picked one (Const.noSupply otherwise).   
+    * <li> int[3]: The dice/direction of the move.
     * </ul>
     */
    @Override
    int[] move(int id) {
       // Initialize return array with the current data
-      int[] ret = new int[Const.moveItems];
-      ret[0] = getNextMove(id);
-      ret[1] = y = Position.toRow(ret[0]);
-      ret[2] = x = Position.toCol(ret[0]);
+      int[] ret = getNextMove(id);
+      y = Position.toRow(ret[MOVE_TILE_ID]);
+      x = Position.toCol(ret[MOVE_TILE_ID]);
+
       int supplyFlag =0, moveFlag =1;
       // In case of a champion player, try also to pick a supply
-      if (champion && (ret[3] = board.tryPickSupply(ret[0])) != Const.noSupply) {
+      if (champion && (board.tryPickSupply(ret[MOVE_TILE_ID]) != Const.noSupply)) {
          ++score;                               // keep score
          ++supplyFlag;
       }
-      int dir = Direction.get(id, ret[0]);      // update direction counters
-      ++dirCounter[dir];
+      ++dirCounter[ret[MOVE_DICE]];             // update direction counters
       board.updateMove(ret, playerId);
 
       // Update supply and opponent distance
       int smin =DirRange.End, omin =DirRange.End;
       for (int d = DirRange.Begin ; d<DirRange.End ; d += DirRange.Step) {
-         int s = supplyInDirection (ret[0], d);
-         int o = opponetInDirection(ret[0], d);
+         int s = supplyInDirection (ret[MOVE_TILE_ID], d);
+         int o = opponetInDirection(ret[MOVE_TILE_ID], d);
          if (s >= 0 && s < smin)  smin = s;
          if (o >= 0 && o < omin)  omin = o;
       }
       // update path
       Integer[] p = {
-            ret[0], dir, moveFlag, supplyFlag,
+            ret[MOVE_TILE_ID], ret[MOVE_DICE], moveFlag, supplyFlag,
             dirCounter[Direction.UP], dirCounter[Direction.RIGHT], dirCounter[Direction.DOWN], dirCounter[Direction.LEFT],
             (smin != DirRange.End)? smin:Const.noSupply, (omin != DirRange.End)? omin:Const.noOpponent
       };
@@ -197,10 +202,10 @@ class HeuristicPlayer extends Player {
          else
             System.out.println("");
          // extra prints for heuristic
-         if (last[8] != Const.noSupply)   System.out.println("            supply distance   =" + last[8]);
-         else                             System.out.println("            supply distance   = blind");
-         if (last[9] != Const.noOpponent) System.out.println("            opponent distance =" + last[9]);
-         else                             System.out.println("            opponent distance = blind");
+         if (last[8] != Const.noSupply)   System.out.println("              supply   =" + last[8]);
+         else                             System.out.println("              supply   = blind");
+         if (last[9] != Const.noOpponent) System.out.println("              opponent =" + last[9]);
+         else                             System.out.println("              opponent = blind");
       }
    }
    

src/host/labyrinth/MinMaxPlayer.java

@@ -0,0 +1,388 @@
+/**
+ * @file MinMaxPlayer.java
+ *
+ * @author
+ *    Anastasia Foti AEM:8959
+ *    <anastaskf@ece.auth.gr>
+ *
+ * @author
+ *    Christos Choutouridis AEM:8997
+ *    <cchoutou@ece.auth.gr>
+ */
+
+package host.labyrinth;
+
+/**
+ * @brief
+ *    This class represents the game's minimax player.
+ */
+class MinMaxPlayer extends Player {
+
+   /** @name Constructors */
+   /** @{ */
+
+   /**
+    * Create a new player and put him at the row-column coordinates 
+    * @param name       The name of the player
+    * @param champion   Flag to indicate if a player is a `champion`
+    * @param board      Reference to the board of the game
+    * @param row        The row coordinate of initial player position
+    * @param column     The column coordinate of initial player's position
+    */
+   public MinMaxPlayer(String name, boolean champion, Board board, int row, int column) throws Exception {
+      super(name, champion, board, row, column);
+   }
+
+   /**
+    * Create a new player and put him at the row-column coordinates 
+    * @param name       The name of the player
+    * @param champion   Flag to indicate if a player is a `champion`
+    * @param board      Reference to the board of the game
+    * @param tileId     The tileId coordinate of player's initial position
+    */
+   public MinMaxPlayer(String name, boolean champion, Board board, int tileId) throws Exception {
+      super(name, champion, board, tileId);
+   }
+   /** @} */
+   /** @name Board's main application interface */
+   /** @{ */
+   
+   /**
+    * Utility to get the distance of a possible supply in some direction
+    * @param currentPos    The current position of the player
+    * @param direction     The direction to check
+    * @param board         Reference to the Board object to use
+    *
+    * @return           The distance or Const.noView
+    */
+   int supplyInDirection(int currentPos, int direction, Board board) {
+      Position pos = new Position(Position.toRow(currentPos), Position.toCol(currentPos));
+
+      for (int i=0 ; i<=Const.viewDistance ; ++i) {
+         if (board.hasSupply(pos.getId()))
+            return i;
+         if (board.isWalkable(pos.getId(), direction))
+            pos = new Position(pos.getRow(), pos.getCol(), direction);
+         else
+            break;
+      } 
+      return Const.noView;
+   }
+
+   /**
+    * Utility to get the distance of a possible opponent in some direction
+    * @param currentPos    The current position of the player
+    * @param direction     The direction to check
+    * @param board         Reference to the Board object to use
+    *
+    * @return           The distance or Const.noView
+    */
+   int opponetInDirection(int currentPos, int direction, Board board) {
+      Position pos = new Position(Position.toRow(currentPos), Position.toCol(currentPos));
+      int[] opp = board.getOpponentMove(playerId);
+
+      for (int i=0 ; i<=Const.viewDistance ; ++i) {
+         if (opp[MOVE_TILE_ID] == pos.getId())
+            return i;
+         if (board.isWalkable(pos.getId(), direction))
+            pos = new Position(pos.getRow(), pos.getCol(), direction);
+         else
+            break;
+      }
+      return Const.noView;
+   }
+
+   /**
+    * This is the main move evaluation function.
+    *
+    * @param currentPos    The current position of the player (before the move to evaluate)
+    * @param direction     The direction (a.k.a. the move) to evaluate
+    * @param board         Reference to the Board object to use
+    * @return              A signed real number. The higher the output, the higher the evaluation.
+    */
+   double evaluate (int currentPos, int direction, Board board) {
+      Position next   = new Position (Position.toRow(currentPos), Position.toCol(currentPos), direction);
+
+      int preOpDist   = opponetInDirection (currentPos, direction, board);
+      int preSupDist  = supplyInDirection(currentPos, direction, board);
+      int postOpDist  = opponetInDirection (next.getId(), direction, board);
+      int postSupDist = supplyInDirection(next.getId(), direction, board);
+
+      return ((preSupDist != Const.noView) ? Const.preMoveFactor *(1.0/(preSupDist+1) * Const.supplyFactor) : 0)
+           - ((preOpDist != Const.noView)  ? Const.preMoveFactor *(1.0/(preOpDist+1)  * Const.opponentFactor) : 0) 
+           + ((postSupDist != Const.noView)? Const.postMoveFactor*(1.0/(preSupDist+1) * Const.supplyFactor) : 0)
+           - ((postOpDist != Const.noView) ? Const.postMoveFactor*(1.0/(preOpDist+1)  * Const.opponentFactor) : 0);
+   }
+
+   /**
+    * Executes the minimax algorithm and return a reference to selected move
+    * @param node    The root node to start
+    * @return        Reference to the selected move
+    */
+   Node chooseMinMaxMove(Node node) {
+      node.setNodeEvaluation(maxValue(node));
+      return node.getPath();
+   }
+
+   /**
+    * Selects the best possible move to return
+    * @param   currentPos  Player's current position to the board
+    * @return  The move array
+    *
+    * @note
+    *    This function always return a new move.
+    */
+   int[] getNextMove(int currentPos) {
+      Node root  = new Node (board);
+      int [] opp = board.getOpponentMove(playerId);
+
+      createMySubtree(currentPos, opp[MOVE_TILE_ID], root, root.getNodeDepth()+1);
+
+      return chooseMinMaxMove(root).getNodeMove();
+   }
+
+   /**
+    * MinMaxPlayer's move.
+    *
+    * A player of this kind cheats. He does not throw a dice to get a direction. In contrary he
+    * calculates his next move very carefully.
+    * If the player is a champion then he also picks up a possible supply from the tile.
+    *
+    * @param id   The id of the starting tile.
+    * @return     An array containing player's final position and possible supply of that position.
+    *             The array format is:
+    * <ul>
+    * <li> int[0]: The tileId of the final player's position.
+    * <li> int[1]: The row of the final player's position.
+    * <li> int[2]: The column of the final player's position.
+    * <li> int[3]: The dice/direction of the move.
+    * </ul>
+    */
+   @Override
+   int[] move(int id) {
+      // Initialize return array with the current data
+      int[] ret = getNextMove(id);
+      y = Position.toRow(ret[MOVE_TILE_ID]);
+      x = Position.toCol(ret[MOVE_TILE_ID]);
+
+      int supplyFlag =0, moveFlag =1;
+      // In case of a champion player, try also to pick a supply
+      if (champion && (board.tryPickSupply(ret[MOVE_TILE_ID]) != Const.noSupply)) {
+         ++score;                               // keep score
+         ++supplyFlag;
+      }
+      ++dirCounter[ret[MOVE_DICE]];             // update direction counters
+      board.updateMove(ret, playerId);
+
+      // Update supply and opponent distance
+      int smin =Const.noView, omin =Const.noView;
+      for (int d = DirRange.Begin ; d<DirRange.End ; d += DirRange.Step) {
+         int s = supplyInDirection (ret[MOVE_TILE_ID], d, board);
+         int o = opponetInDirection(ret[MOVE_TILE_ID], d, board);
+         if (s < smin)  smin = s;
+         if (o < omin)  omin = o;
+      }
+      // update path
+      Integer[] p = {
+            ret[MOVE_TILE_ID], ret[MOVE_DICE], moveFlag, supplyFlag,
+            dirCounter[Direction.UP], dirCounter[Direction.RIGHT], dirCounter[Direction.DOWN], dirCounter[Direction.LEFT],
+            smin, omin
+      };
+      path.add(p);
+      return ret;
+   }
+
+   /**
+    * Prints round information for the player
+    */
+   void statistics() {
+      if (!path.isEmpty()) {
+         Integer[] last = path.get(path.size()-1);
+         String who = String.format("%12s", name);
+         System.out.print(who + ": score[" + score + "]" + ", dice =" + last[1] + ", tileId =" + last[0] + " (" + Position.toRow(last[0]) + ", " + Position.toCol(last[0]) + ")");
+         if (last[2] == 0)
+            System.out.println(" *Can not move.");
+         else if (last[3] != 0)
+            System.out.println(" *Found a supply.");
+         else
+            System.out.println("");
+         // extra prints for minimax player
+         if (last[8] != Const.noView) System.out.println("              supply   =" + last[8]);
+         else                         System.out.println("              supply   = blind");
+         if (last[9] != Const.noView) System.out.println("              opponent =" + last[9]);
+         else                         System.out.println("              opponent = blind");
+      }
+   }
+   
+   /**
+    * Prints final statistics for the player
+    */
+   void final_statistics () {
+      String who = String.format("%12s", name);
+      System.out.println();
+      System.out.println(who + ": score[" + score + "]");
+      System.out.println("    Moves up: " + dirCounter[Direction.UP]);
+      System.out.println(" Moves right: " + dirCounter[Direction.RIGHT]);
+      System.out.println("  Moves down: " + dirCounter[Direction.DOWN]);
+      System.out.println("  Moves left: " + dirCounter[Direction.LEFT]);
+   }
+
+   /** @} */
+
+   /** @name Minimax algorithm related part */
+   /** @{ */
+
+   /**
+    * Get the previous direction of the player
+    * @param   parent   Reference to previous nNode
+    * @return  The previous direction if exist, else return Direction.NONE
+    */
+   private int prevDirection(Node parent) {
+      if (parent != null && parent.getParent() != null)
+         return parent.getParent().getNodeMove()[MOVE_DICE];
+      return Direction.NONE;
+   }
+
+   /**
+    * A simulated move in a copy of the bard.
+    *
+    * @param board         The board on witch we simulate the move
+    * @param currentPos    The current position of the player to the @c board
+    * @param dir           The direction of the move
+    * @param champion      Flag to indicate if the player is champion or not
+    * @return              The move array
+    */
+   private int[] dryMove (Board board, int currentPos, int dir, boolean champion) {
+      int[] ret = new int[MOVE_DATA_SIZE];
+      Position p = new Position(Position.toRow(currentPos), Position.toCol(currentPos), dir);
+      ret[MOVE_TILE_ID] = p.getId();
+      ret[MOVE_ROW]     = p.getRow();
+      ret[MOVE_COLUMN]  = p.getCol();
+      ret[MOVE_DICE]    = dir; 
+
+      board.updateMove(ret, (champion) ? playerId : board.getOpponentId(playerId));
+      return ret;
+   }
+
+   /**
+    * One of the 2 recursive functions for creating the minimax tree. This one 
+    * creates children for the MinMax player.
+    *
+    * @param parent        The parent Node
+    * @param depth         The current depth for the children
+    * @param currentPos    The tile of MinMax player
+    * @param oppCurrentPos The tile of the opponent
+    *
+    * @note
+    *    Even though unnecessary we calculate the evaluation for every node and not only for the leafs.
+    *    This follows the exercise instructions. We could also rely on lazy evaluation of "evaluation()"
+    *    and use AB pruning but the depth of the tree is not worth the try.
+    */
+   private void createMySubtree (int currentPos, int oppCurrentPos, Node parent, int depth) {
+      ShuffledRange dirs = new ShuffledRange(DirRange.Begin, DirRange.End, DirRange.Step);
+      int [] nodeMove;
+      
+      for (int dir = dirs.get() ; dir != Const.EOR ; dir = dirs.get()) {
+         if ((dir != Direction.opposite(prevDirection(parent)))
+          && parent.getNodeBoard().isWalkable(currentPos, dir)) {
+            Board nodeBoard = new Board (parent.getNodeBoard());     // clone board
+            double eval = evaluate (currentPos, dir, nodeBoard);     // evaluate the move
+            nodeMove = dryMove (nodeBoard, currentPos, dir, true);   // simulate the move
+            // make child Node
+            Node child = new Node (parent, depth, nodeMove, nodeBoard, eval);
+            parent.addChild(child);                                  // add child to tree
+            createOppSubtree (nodeMove[MOVE_TILE_ID], oppCurrentPos, child, depth+1);
+         }
+      }
+   }
+
+   /**
+    * One of the 2 recursive functions for creating the minimax tree. This one 
+    * creates children for the opponent player.
+    *
+    * @param parent        The parent Node
+    * @param depth         The current depth for the children
+    * @param currentPos    The tile of MinMax player
+    * @param oppCurrentPos The tile of the opponent
+    *
+    * @note
+    *    Even though unnecessary we calculate the evaluation for every node and not only for the leafs.
+    *    This follows the exercise instructions. We could also rely on lazy evaluation of "evaluation()"
+    *    and use AB pruning but the depth of the tree is not worth the try.
+    */
+   private void createOppSubtree (int currentPos, int oppCurrentPos, Node parent, int depth) {
+      ShuffledRange dirs = new ShuffledRange(DirRange.Begin, DirRange.End, DirRange.Step);
+      int [] nodeMove;
+      
+      for (int dir = dirs.get() ; dir != Const.EOR ; dir = dirs.get()) {
+         if ((dir != Direction.opposite(prevDirection(parent)))
+               && parent.getNodeBoard().isWalkable(oppCurrentPos, dir)) {
+            Board nodeBoard = new Board(parent.getNodeBoard());         // clone board
+            nodeMove = dryMove (nodeBoard, oppCurrentPos, dir, false);  // simulate move
+            Position init = new Position(                               // evaluate from "My" perspective the move
+                  parent.getNodeMove()[MOVE_ROW],
+                  parent.getNodeMove()[MOVE_COLUMN],
+                  Direction.opposite(parent.getNodeMove()[MOVE_DICE])
+            );
+            double eval = evaluate(init.getId(), parent.getNodeMove()[MOVE_DICE], nodeBoard);
+            // make child Node
+            Node child = new Node (parent, depth, nodeMove, nodeBoard, eval);
+            parent.addChild(child);                                     // add child to tree
+            if (depth < Const.minimaxTreeDepth) {
+               createMySubtree (currentPos, nodeMove[MOVE_TILE_ID], child, depth+1);
+            }
+         }
+      }
+   }
+   
+   /**
+    * The Minimax recursive function for the maximizing part.
+    *
+    * @param node The current Node
+    * @return     The selected Node
+    */
+   private double maxValue (Node node) {
+      if (node.getChildren() == null) {
+         node.setPath(node);
+         return node.getNodeEvaluation();
+      }
+      else {
+         double M = Double.NEGATIVE_INFINITY;
+         for (Node n : node.getChildren()) {
+            n.setNodeEvaluation(minValue(n));   // evaluation propagation
+            if (M < n.getNodeEvaluation()) {
+               M = n.getNodeEvaluation();
+               node.setPath(n);                 // path propagation
+            }
+         }
+         return M;
+      }
+   }
+   
+   /**
+    * The Minimax recursive function for the minimizing part.
+    *
+    * @param node The current Node
+    * @return     The selected Node
+    */
+   private double minValue (Node node) {
+      if (node.getChildren() == null) {
+         node.setPath(node);
+         return node.getNodeEvaluation();
+      }
+      else {
+         double m = Double.POSITIVE_INFINITY;
+         for (Node n : node.getChildren()) {
+            n.setNodeEvaluation(maxValue(n));   // evaluation propagation
+            if (m > n.getNodeEvaluation()) {
+               m = n.getNodeEvaluation();
+               node.setPath(n);                 // path propagation
+            }
+         }
+         return m;
+      }
+   }
+
+   /** @} */
+   
+}

src/host/labyrinth/Node.java

@@ -0,0 +1,119 @@
+/**
+ * @file Node.java
+ *
+ * @author
+ *    Anastasia Foti AEM:8959
+ *    <anastaskf@ece.auth.gr>
+ *
+ * @author
+ *    Christos Choutouridis AEM:8997
+ *    <cchoutou@ece.auth.gr>
+ */
+
+package host.labyrinth;
+
+import java.util.ArrayList;
+
+/**
+ * Node object for minimax tree.
+ */
+class Node {
+
+   /** @name Constructors */
+   /** @{ */
+   /** Null initialize constructor */
+   Node () { }
+   /** The main constructor for the Node */
+   Node (Node parent, int nodeDepth, int [] nodeMove, Board nodeBoard, double nodeEvaluation) {
+      this.parent          = parent;
+      this.children        = null;
+      this.nodeDepth       = nodeDepth;
+      this.nodeMove        = nodeMove;
+      this.nodeBoard       = nodeBoard;
+      this.nodeEvaluation  = nodeEvaluation;
+      this.path            = null;
+   }
+   /** A special constructor for creating a root Node */
+   Node (Board nodeBoard) {
+      this.parent          = null;
+      this.children        = null;
+      this.nodeDepth       = 0;
+      this.nodeMove        = new int [4];
+      this.nodeBoard       = nodeBoard;
+      this.nodeEvaluation  = 0;
+      this.path            = null;
+   }
+   /**@} */
+   
+   /** @name Get/Set interface */
+   /** @{ */
+   /** Get parent */
+   Node getParent()           { return parent; }
+   /** get children */
+   ArrayList<Node>
+      getChildren()           { return children; }
+   /** get nodeDepth */
+   int getNodeDepth()         { return nodeDepth; }
+   /** get nodeMove */
+   int[] getNodeMove()        { return nodeMove; }
+   /** get nodeBoard */
+   Board getNodeBoard()       { return nodeBoard; }
+   /** get nodeEvluation */
+   double getNodeEvaluation (){ return nodeEvaluation; }
+   /** get path */
+   Node getPath()             { return path; }
+
+   /** set parent */
+   void setParent(Node parent) { this.parent = parent; }
+   /** set children */
+   void setChildren(ArrayList<Node> children) {
+      this.children = children;
+   }
+   /** set nodeDepth */
+   void setNodeDepth(int nodeDepth) {
+      this.nodeDepth = nodeDepth;
+   }
+   /** set nodeMove */
+   void setNodeMove(int[] nodeMove) {
+      this.nodeMove = nodeMove;
+   }
+   /** set nodeBoard */
+   void setNodeBoard(Board nodeBoard) {
+      this.nodeBoard = nodeBoard;
+   }
+   /** set nodeEvaluation */
+   void setNodeEvaluation(double nodeEvaluation) {
+      this.nodeEvaluation = nodeEvaluation;
+   }
+   /** set path */
+   void setPath (Node path) {
+      this.path = path;
+   }
+
+   /**@}*/
+
+   /** @name Public API */
+   /** @{ */
+   /**
+    * Add a child to the tree
+    * @param   child   The child to add
+    * @return  the status of the operation
+    */
+   boolean addChild (Node child) {
+      if (children == null)
+         children = new ArrayList<>();
+      return children.add(child);
+   }
+   /**@}*/
+
+   /** @name Data members */
+   /** @{ */
+   private Node            parent;     /**< Back reference to parent Node */
+   private ArrayList<Node> children;   /**< Fwd reference to leaf Nodes */
+   private int             nodeDepth;  /**< The Node's depth */
+   private int[]           nodeMove;   /**< The Node's move data [tile, initTile, points, roll]*/
+   private Board           nodeBoard;  /**< Reference to Board's copy of the current node*/
+   private double          nodeEvaluation; /**< The Node's evaluation result */
+   private Node            path;       /**< The minimax evaluation path */
+   /**@}*/
+}

src/host/labyrinth/Player.java

@@ -19,6 +19,13 @@ import java.util.ArrayList;
  *    This class represents the game's player
  */
 class Player {
+   /** Helper variables to keep track of the move() return values @see move() */
+   static final int MOVE_DATA_SIZE        = 4;  /**< The move return data array size */
+   static final int MOVE_TILE_ID          = 0;  /**< Index of the tileId information of the move */
+   static final int MOVE_ROW              = 1;  /**< The index of row information */
+   static final int MOVE_COLUMN           = 2;  /**< The index of column information */
+   static final int MOVE_DICE             = 3;  /**< The index of dice information */
+
    /** @name Constructors */
    /** @{ */
 
@@ -30,7 +37,7 @@ class Player {
     * @param row        The row coordinate of initial player position
     * @param column     The column coordinate of initial player's position
     */
-   Player(String name, boolean champion, Board board, int row, int column) {
+   Player(String name, boolean champion, Board board, int row, int column) throws Exception {
       this.playerId  = board.generatePlayerId();
       this.name      = name;
       this.board     = board;
@@ -38,7 +45,7 @@ class Player {
       this.x         = column;
       this.y         = row;
       this.champion  = champion;
-      this.dirCounter= new int[DirRange.End];      // yes we spoil some memory. Java is worst.
+      this.dirCounter= new int[DirRange.End];      // yes we spoil some memory. Java is the worst.
       this.path      = new ArrayList<Integer[]>();
       int[] m        = {
             Position.toID(row, column), row, column, Const.noSupply
@@ -53,7 +60,7 @@ class Player {
     * @param board      Reference to the board of the game
     * @param tileId     The tileId coordinate of player's initial position
     */
-   Player(String name, boolean champion, Board board, int tileId) {
+   Player(String name, boolean champion, Board board, int tileId) throws Exception {
       this.playerId  = board.generatePlayerId();
       this.name      = name;
       this.board     = board;
@@ -61,7 +68,7 @@ class Player {
       this.x         = Position.toCol(tileId);
       this.y         = Position.toRow(tileId);
       this.champion  = champion;
-      this.dirCounter= new int[DirRange.End];      // yes we spoil some memory. Java is worst.
+      this.dirCounter= new int[DirRange.End];      // yes we spoil some memory. Java is the worst.
       this.path      = new ArrayList<Integer[]>();
       int[] m        = {
             tileId, Position.toRow(tileId), Position.toCol(tileId), Const.noSupply
@@ -87,37 +94,39 @@ class Player {
     * <li> int[0]: The tileId of the final player's position.
     * <li> int[1]: The row of the final player's position.
     * <li> int[2]: The column of the final player's position.
-    * <li> int[1]: The supplyId in case player picked one (Const.noSupply otherwise).   
+    * <li> int[3]: The dice/direction of the move.
     * </ul>
     */
    int[] move(int id) {
       // Initialize return array with the current data
-      int[] ret = new int[Const.moveItems];
-      ret[0] = id;
-      ret[1] = Position.toRow(id);
-      ret[2] = Position.toCol(id);
-      ret[3] = Const.noSupply;
+      int[] ret = new int[MOVE_DATA_SIZE];
+      ret[MOVE_TILE_ID]    = id;
+      ret[MOVE_ROW]        = Position.toRow(id);
+      ret[MOVE_COLUMN]     = Position.toCol(id);
+      ret[MOVE_DICE]       = Direction.NONE;
       int supplyFlag =0, moveFlag =0;
 
-      int diceDirection = board.dice();            // throw the dice
-      if (board.isWalkable(id, diceDirection)) {   // The result is walkable
-         moveFlag =1;                              // mark the successful move
-         // Get next tile
-         Position next = new Position(Position.toRow(id), Position.toCol(id), diceDirection);
-         ret[0] = next.getId();                    // Update player's and return data
-         ret[1] = y = next.getRow();
-         ret[2] = x = next.getCol();
-         // In case of a champion player, try also to pick a supply
-         if (champion && (ret[3] = board.tryPickSupply(next.getId())) != Const.noSupply) {
-            supplyFlag =1;                         // mark the successful supply pickup
-            ++score;                               // keep score
-         }
-         ++dirCounter[diceDirection];              // update direction counters
-         board.updateMove(ret, playerId);
+      int diceDirection;
+      do
+         diceDirection = board.dice();          // throw the dice
+      while (!board.isWalkable(id, diceDirection));
+      moveFlag =1;                              // mark the successful move
+      // Get next tile
+      Position next = new Position(Position.toRow(id), Position.toCol(id), diceDirection);
+      ret[MOVE_TILE_ID] = next.getId();         // Update move's return data
+      ret[MOVE_ROW]     = y = next.getRow();
+      ret[MOVE_COLUMN]  = x = next.getCol();
+      ret[MOVE_DICE]    = diceDirection;
+      // In case of a champion player, try also to pick a supply
+      if (champion && (board.tryPickSupply(next.getId()) != Const.noSupply)) {
+         supplyFlag =1;                         // mark the successful supply pickup
+         ++score;                               // keep score
       }
+      ++dirCounter[diceDirection];              // update direction counters
+      board.updateMove(ret, playerId);
       // update path
       Integer[] p = {
-            ret[0], diceDirection, moveFlag, supplyFlag,
+            ret[MOVE_TILE_ID], diceDirection, moveFlag, supplyFlag,
             dirCounter[Direction.UP], dirCounter[Direction.RIGHT], dirCounter[Direction.DOWN], dirCounter[Direction.LEFT],
             Const.noSupply, Const.noOpponent
       };