DEV: An extra closed room preventing algorithm added.

.gitignore

@@ -1,5 +1,6 @@
 bin/
 doc/
+out/
 deliverable/
 .classpath
 .project

src/net/hoo2/auth/labyrinth/Board.java

@@ -7,6 +7,7 @@
 
 package net.hoo2.auth.labyrinth;
 
+import java.util.ArrayList;
 import java.util.function.IntFunction;
 
 /**
@@ -24,26 +25,27 @@ class Board {
     * The empty constructor for default initialization
     */
    Board() {
-      this.N = this.S = this.W = 0;
-      this.tiles = null;
-      this.supplies =null;
+      this.N   = 0;
+      this.S   = 0;
+      this.W   = 0;
+      tiles    = null;
+      supplies =null;
+      walls    = new ArrayList<Edge>();
    }
 
    /**
     * The main constructor for the application
     * @param N    The size of each edge of the board
     * @param S    The number of supplies on the board
-    * @param W    The number of walls on the board
     */
-   Board(int N, int S, int W) {
-      assert (W>= 4*N-1 && W<=(3*N*N+1)/2 )
-         : "Boards walls has to be in the range [4N-1, (3N^2+1)/2]";
-
+   Board(int N, int S) {
+      assert (N%2 != 0) : "Board's size has to be an odd number.";
       this.N   = Session.boardSize = N;
       this.S   = S;
-      this.W   = W;
+      this.W   = 0;
       tiles    = new Tile[N*N];
       supplies = new Supply[S];
+      walls    = new ArrayList<Edge>();
    }
 
    /**
@@ -67,6 +69,7 @@ class Board {
       // Clone arrays
       this.tiles     = b.tiles.clone();
       this.supplies  = b.supplies.clone();
+      this.walls     = b.walls;
    }
    /** @} */
 
@@ -79,7 +82,7 @@ class Board {
     * @param theseusTile
     * @param minotaurTile
     */
-   void createBoard(int theseusTile, int minotaurTile) throws Exception {
+   void createBoard(int theseusTile, int minotaurTile) {
       createTiles();
       createSupplies(theseusTile, minotaurTile);
    }
@@ -220,6 +223,15 @@ class Board {
    void setSupplies(Supply[] supplies)   { this.supplies= supplies; }
    /** @} */
 
+
+   /** @name Sentinel predicates */
+   /** @{ */
+   private boolean isLeftSentinel (int tileId)  { return (Position.toCol(tileId) == 0); }
+   private boolean isRightSentinel (int tileId) { return (Position.toCol(tileId) == N-1); }
+   private boolean isUpSentinel (int tileId)    { return (Position.toRow(tileId) == N-1); }
+   private boolean isDownSentinel (int tileId)  { return (Position.toRow(tileId) == 0); }
+   /** @} */
+
    /**
     * @name private functionality of the object
     */
@@ -228,11 +240,11 @@ class Board {
    /**
     * This function creates randomly all the tiles of the board
     */
-   private void createTiles() throws Exception {
-      int wallPool = W;
-      wallPool -= createBasicTileWalls ();   // First create tiles with outer walls
-      if (createInnerWalls(wallPool) > 0)    // Create inner walls with the rest of the requested walls
-         throw new Exception("Can not create the requested number of walls");
+   private void createTiles() {
+      int wallCount;
+      wallCount  = createBasicTileWalls ();  // First create tiles with outer walls
+      wallCount += createInnerWalls();       // Greedy create as many inner walls we can
+      W = wallCount;
    }
 
    /**
@@ -254,13 +266,43 @@ class Board {
       }
    }
 
-   /** @name Sentinel predicates */
-   /** @{ */
-   private boolean isLeftSentinel (int tileId)  { return (Position.toCol(tileId) == 0); }
-   private boolean isRightSentinel (int tileId) { return (Position.toCol(tileId) == N-1); }
-   private boolean isUpSentinel (int tileId)    { return (Position.toRow(tileId) == N-1); }
-   private boolean isDownSentinel (int tileId)  { return (Position.toRow(tileId) == 0); }
-   /** @} */
+   /**
+    * Predicate to check if a wall creates a closed room.
+    *
+    * This algorithm has a complexity of O(N^2) where N represents the total
+    * number of tiles it should be used with care.
+    *
+    * @param tileId     The tileId of the wall where the wall is.
+    * @param direction  The wall's relative direction from the tile. 
+    * @return           True if the wall creates a closed room, false otherwise.
+    */
+   private boolean createsClosedRoom (int tileId, int direction) {
+      // Get a snapshot of the current walls
+      ArrayList<Edge> w = new ArrayList<Edge>();
+      for (Edge it : walls)
+         w.add(new Edge(it));
+      // Create a graph from the current wall(edge)
+      // and populate the graph with all the edges we can attach.
+      Graph g = new Graph(new Edge(tileId, direction));
+      int size;
+      do {
+         size = w.size();
+         for (int i =0, S=w.size() ; i<S ; ++i)
+            if (g.attach(w.get(i))) {
+               w.remove(i);
+               --i; --S;
+            }
+      } while (size != w.size());
+
+      // Search if a vertex is attached more than once.
+      // This means that there is at least 2 links to the same node
+      // so the graph has a closed loop
+      for (Edge it : walls) {
+         if (g.count(it.getV1()) > 1)  return true;
+         if (g.count(it.getV2()) > 1)  return true;
+      }
+      return false;
+   }
 
    /**
     * Predicate to check if a tile direction is `Wallable`.
@@ -270,6 +312,7 @@ class Board {
     * <li>The wall is not the DOWN wall from tile (0, 0).
     * <li>There is not already a wall in the desired direction. (Implies no sentinel tile).
     * <li>The neighbor in this direction has at most `Const.maxTileWalls -1` walls.
+    * <li>The wall does not create a closed room (Optional requirement).
     * </ul>
     *
     * @note
@@ -286,12 +329,22 @@ class Board {
       if (tiles[tileId].hasWall(direction))
          return false;
       switch (direction) {
-         case Direction.UP:   return (tiles[upTileId.apply(tileId)].hasWalls() < Const.maxTileWalls);
-         case Direction.DOWN: return (tiles[downTileId.apply(tileId)].hasWalls() < Const.maxTileWalls);
-         case Direction.LEFT: return (tiles[leftTileId.apply(tileId)].hasWalls() < Const.maxTileWalls);
-         case Direction.RIGHT:return (tiles[rightTileId.apply(tileId)].hasWalls() < Const.maxTileWalls);
+         case Direction.UP:
+            if (tiles[upTileId.apply(tileId)].hasWalls() >= Const.maxTileWalls)  return false;
+            break;
+         case Direction.DOWN:
+            if (tiles[downTileId.apply(tileId)].hasWalls() >= Const.maxTileWalls)  return false;
+            break;
+         case Direction.LEFT:
+            if (tiles[leftTileId.apply(tileId)].hasWalls() >= Const.maxTileWalls)  return false;
+            break;
+         case Direction.RIGHT:
+            if (tiles[rightTileId.apply(tileId)].hasWalls() >= Const.maxTileWalls)  return false;
+            break;
       }
-      return false;
+      if (Session.loopGuard && createsClosedRoom(tileId, direction))
+         return false;
+      return true;
    }
 
    /**
@@ -326,16 +379,22 @@ class Board {
     * @return  The number of walls created from the utility.
     */
    private int createBasicTileWalls () {
-      int tileCount =0;
+      int wallCount =0;
       for (int i =0 ; i< tiles.length ; ++i) {
          boolean up    = isUpSentinel(i);
          boolean down  = isDownSentinel(i) && (i != 0);
          boolean left  = isLeftSentinel(i);
          boolean right = isRightSentinel(i);
-         tileCount += ((up?1:0) + (down?1:0) + (left?1:0) + (right?1:0));
+         wallCount += ((up?1:0) + (down?1:0) + (left?1:0) + (right?1:0));
          tiles[i] = new Tile (i, up, down, left, right);
+         if (Session.loopGuard) {
+            if (up)     walls.add(new Edge(i, Direction.UP));
+            if (down)   walls.add(new Edge(i, Direction.DOWN));
+            if (left)   walls.add(new Edge(i, Direction.LEFT));
+            if (right)  walls.add(new Edge(i, Direction.RIGHT));
+         }
       }
-      return tileCount;
+      return wallCount;
    }
 
    /**
@@ -352,6 +411,8 @@ class Board {
       Position neighbor = new Position(Position.toRow(tileId), Position.toCol(tileId), dir);
       tiles[tileId].setWall(dir);
       tiles[neighbor.getId()].setWall(Direction.opposite(dir));
+      if (Session.loopGuard)
+         walls.add(new Edge(tileId, dir));
    }
 
    /**
@@ -360,23 +421,23 @@ class Board {
     * @param walls   The number of walls to create   
     * @return        The number of walls failed to create.
     */
-   private int createInnerWalls (int walls) {
+   private int createInnerWalls () {
       ShuffledRange randTiles = new ShuffledRange(0, N*N);
-      for (int tileId, i =0, shuffleMark =0 ; i<walls ; ++i) {
+      for (int tileId, i =0, walls =0, shuffleMark =0 ; true ; ) {
          // randomly pick a wallable tile.
          do {
             if ((tileId = randTiles.get())== Const.noTileId) {
                if (i == shuffleMark)   // Wallable tiles exhausted.
-                  return walls - i;
+                  return walls;
                else {                  // Re-shuffle and continue.
                   randTiles = new ShuffledRange(0, N*N);
                   shuffleMark =i;
                }
             }
          } while (!isWallable(tileId));
+         ++walls;
          createInnerWall(tileId);
       }
-      return 0;
    }
 
    /**
@@ -456,10 +517,14 @@ class Board {
 
    /** @name Class data */
    /** @{ */
-   private int    N;          /**< The size of each edge of the board */
-   private int    S;          /**< The number of the supplies on the board */
-   private int    W;          /**< The number of walls on the board */
-   private Tile[] tiles;      /**< Array to hold all the tiles for the board */
-   private Supply[] supplies; /**< Array to hold all the supplies on the board */
+   private int    N;                /**< The size of each edge of the board */
+   private int    S;                /**< The number of the supplies on the board */
+   private int    W;                /**< The number of walls on the board */
+   private Tile[] tiles;            /**< Array to hold all the tiles for the board */
+   private Supply[] supplies;       /**< Array to hold all the supplies on the board */
+   private ArrayList<Edge> walls;   /**<
+                                     *  Array to hold all the walls using the edge representation 
+                                     *  required by the closed room preventing algorithm. 
+                                     */
    /** @} */
 }

src/net/hoo2/auth/labyrinth/Common.java

@@ -21,9 +21,11 @@ class Const {
  * Application wide object to hold settings like values for the session.
  */
 class Session {
-   static int  boardSize = 15;      /**< Default board's size (if no one set it via command line) */
-   static int  supplySize = 4;      /**< Default board's supply size (if no one set it via command line) */
-   static int  wallSize = 4*15-1;   /**< Default board's wall size (if no one set it via command line) */
+   static int  boardSize = 15;         /**< Default board's size (if no one set it via command line) */
+   static int  supplySize = 4;         /**< Default board's supply size (if no one set it via command line) */
+   static int  maxRounds = 100;        /**< Default number of rounds per game (if no one set it via command line) */
+   static boolean loopGuard = false;   /**< When true a wall creation guard is added to prevent closed rooms inside the board */
+   static boolean interactive = false; /**< When true each round of the game requires user input */
 }
 
 /**
@@ -209,3 +211,179 @@ class ShuffledRange extends Range {
       Collections.shuffle(numbers);
    }
 }
+
+/**
+ * @brief
+ *    A utility class used for room prevent algorithm.
+ *
+ * This class is the wall representation we use in the room preventing algorithm.
+ * In this algorithm we represent the crosses between tiles as nodes (V) of a graph and the
+ * walls as edges. So for example:
+ * 
+ *                  _ V = 15 
+ *                 /
+ *    +---+---+---+     We have a 4x4=16 vertices board(nodes) and 14 edges(walls).
+ *    |           |     To represent the vertices on the board we use the
+ *    +   +---+   +     same trick as the tileId.
+ *    |       |   |     The edges are represented as vertices pairs.
+ *    +   +   +   + <.
+ *    |   |       |   \_ V = 7
+ *    +   +---+---+
+ *    ^           ^
+ *   V = 0      V = 3
+ *
+ * @note
+ *    Beside the fact that we prefer this kind of representation of the walls in
+ *    the application we use the one that is suggested from the assignment. This is
+ *    used only in room preventing algorithm.
+ * @note
+ *    Using this kind of representation we don't have any more the "problem"
+ *    of setting the wall in both neighbor tiles.
+ */
+class Edge {
+   /**
+    * This constructor as as the interface between the application's wall
+    * representation and the one based on graph.
+    * @param tileId     The tile id of the wall.
+    * @param direction  The direction of the tile where the wall should be.
+    */
+   Edge(int tileId, int direction) {
+      int N = Session.boardSize +1;
+      switch (direction) {
+         case Direction.UP:
+            v1= (Position.toRow(tileId) + 1)*N + Position.toCol(tileId);
+            v2= (Position.toRow(tileId) + 1)*N + Position.toCol(tileId) + 1;
+            break;
+         case Direction.DOWN:
+            v1= (Position.toRow(tileId))*N + Position.toCol(tileId);
+            v2= (Position.toRow(tileId))*N + Position.toCol(tileId) + 1;
+            break;
+         case Direction.LEFT:
+            v1= (Position.toRow(tileId))*N + Position.toCol(tileId);
+            v2= (Position.toRow(tileId) + 1)*N + Position.toCol(tileId);
+            break;
+         case Direction.RIGHT:
+            v1= (Position.toRow(tileId))*N + Position.toCol(tileId) + 1;
+            v2= (Position.toRow(tileId) + 1)*N + Position.toCol(tileId) +1;
+            break;
+      }
+   }
+   /** A deep copy contructor */
+   Edge(Edge e) {
+      v1 = e.getV1();
+      v2 = e.getV2();
+   }
+   /** Access of the first node of the edge */
+   int getV1() { return v1; }
+   /** Access of the second node of the edge */
+   int getV2() { return v2; }
+
+   private int v1;   /**< First vertex of the edge */
+   private int v2;   /**< Second vertex of the edge */
+}
+
+/**
+ * @brief
+ *    Provides a graph functionality for the room preventing algorithm.
+ * We use a graph to represent the wall structure of the walls. This way
+ * is easy to find any closed loops. Using graph we transform the problem
+ * of the closed room in the problem of finding a non simple graph.
+ *
+ * If the board has non connected wall structure then we need more than
+ * one graph to represent it.
+ * 
+ * An example graph from a board, starting from V=1 is:
+ * <pre>
+ *    6---7   8                (1)
+ *    |       |               /  \
+ *    3   4   5             (4)  (2)
+ *    |   |   |                    \
+ *    0   1---2                    (5)--(8)
+ * </pre>
+ */
+class Graph {
+   /**
+    * Constructs a node of the graph using the value of a vertex(node).
+    * @param v    The verteg to attach.
+    */
+   Graph (int v) {
+      V = v;
+      E = new ArrayList<Graph>();
+   }
+   /**
+    * Constructor that transform an edge into graph.
+    * @param e    The edge to transform.
+    */
+   Graph (Edge e) {
+      V = e.getV1();
+      E = new ArrayList<Graph>();
+      E.add(new Graph(e.getV2()));
+   }
+
+   /** Access to the current vertex */
+   int getV()  { return V; }
+   /** Access to the links of the current vertex */
+   ArrayList<Graph> getE() { return E; }
+
+   /**
+    * Attach an edge into a graph IFF the graph already has a vertex
+    * with the same value of one of the vertices of the edge.
+    * @param e    The edge to attach.
+    * @return     The status of the operation.
+    *    @arg     True on success
+    *    @arg     False on failure
+    */
+   boolean attach (Edge e) { 
+      return tryAttach(e, 0) > 0;
+   }
+
+   /**
+    * Counts the number of vertices on the graph with the value of `v`
+    * @param v    The vertex to count
+    * @return     The number of vertices with value `v`
+    */
+   int count (int v) {
+      return tryCount (v, 0);
+   }
+
+   /**
+    * Recursive algorithm that tries to attach an edge into a graph
+    * IFF the graph already has a vertex.
+    * with the same value of one of the vertices of the edge.
+    * @param e       The edge to attach.
+    * @param count   An initial count value to feed to the algorithm.
+    * @return     The status of the operation.
+    *    @arg     True on success
+    *    @arg     False on failure
+    */
+   private int tryAttach (Edge e, int count) {
+      for (Graph n: E)
+         count += n.tryAttach (e, count);
+      if (V == e.getV1()) {
+         E.add(new Graph(e.getV2()));
+         ++count;
+         }
+      if (V == e.getV2()) {
+         E.add(new Graph(e.getV1()));
+         ++count;
+      }
+      return count;
+   }
+
+   /**
+    * Recursive algorithm that tries to count the number of vertices
+    * on the graph with the value of `v`
+    * @param v       The vertex to count
+    * @param count   An initial count value to feed to the algorithm.
+    * @return     The number of vertices with value `v`
+    */
+   private int tryCount (int v, int count) {
+      for (Graph n: E)
+         count = n.tryCount (v, count);
+      if (V == v)
+         return ++count;
+      return count;
+   }
+   private int V;                /**< The value of the current vertex/node */
+   private ArrayList<Graph> E;   /**< A list of all the child nodes */
+}

src/net/hoo2/auth/labyrinth/Game.java

@@ -68,33 +68,44 @@ public class Game {
                   Session.boardSize = Integer.parseInt(args[++i]);
                break;
 
-            case "-w":
-            case "--walls":
-               if (i+1 < args.length)
-                  Session.wallSize = Integer.parseInt(args[++i]);
-               break;
-
             case "-s":
             case "--suplies":
                if (i+1 < args.length)
                   Session.supplySize = Integer.parseInt(args[++i]);
                break;
 
+            case "-r":
+            case "--rounds":
+               if (i+1 < args.length)
+                  Session.maxRounds = Integer.parseInt(args[++i]);
+               break;
+
+            case "--norooms":
+               Session.loopGuard = true;
+               break;
+               
+            case "-i":
+            case "--interactive":
+               Session.interactive = true;
+               break;
+
             default:
             case "-h":
             case "--help":
                System.out.println("Labyrinth Game");
                System.out.println("");
                System.out.println("Usage:");
-               System.out.println("labyrinth [-b|--board <Num>] [-w|--walls <Num>] [-s|--supplies <Num>]");
+               System.out.println("labyrinth [-b|--board <Num>] [-s|--supplies <Num>] [-r|--rounds <Num>] [--norooms] [-i|--interactive]");
                System.out.println("or");
                System.out.println("labyrinth -h|--help");
-               System.out.println("");
-               System.out.println("\t-b | --board:    Sets the size of board's edge.");
-               System.out.println("\t-w | --walls:    Sets the number of walls on the board.");
-               System.out.println("\t-s | --supplies: Sets the number of supplies on the board.");
-               System.out.println("\t-h | --help:     Print this and exit");
-               break;
+               System.out.println("\nOptions\n");
+               System.out.println("-b  | --board:\n   Sets the size of board's edge.\n");
+               System.out.println("-s  | --supplies:\n   Sets the number of supplies on the board.\n");
+               System.out.println("-r  | --rounds:\n   Sets the maximum number of rounds of the game.\n");
+               System.out.println("--norooms:\n   Prevents the creation of closed rooms inside the board.\n");
+               System.out.println("-i  | --interactive:\n   Each round requires user input in order to continue.\n");
+               System.out.println("-h  | --help:\n   Print this and exits.");
+               return false;
          }
       }
       return true;
@@ -111,9 +122,9 @@ public class Game {
 
          // Create a game, a board and 2 players.
          Game game   = new Game();
-         Board board = new Board(Session.boardSize, Session.supplySize, Session.wallSize);
-         Player T    = new Player(1, "Theseus", board, 0);
-         Player M    = new Player(2, "Minotaur", board, Position.toID(Session.boardSize/2, Session.boardSize/2));
+         Board board = new Board(Session.boardSize, Session.supplySize);
+         Player T    = new Player(1, "Theseus", true, board, 0);
+         Player M    = new Player(2, "Minotaur", false, board, Position.toID(Session.boardSize/2, Session.boardSize/2));
 
          // Populate data to the board
          board.createBoard(T.playerTileId(), M.playerTileId());