3 files changed, 33 insertions, 14 deletions

diff --git a/Scala/streams/src/main/scala/streams/GameDef.scala b/Scala/streams/src/main/scala/streams/GameDef.scala
index 22a679e..d04079d 100644
--- a/Scala/streams/src/main/scala/streams/GameDef.scala
+++ b/Scala/streams/src/main/scala/streams/GameDef.scala
@@ -84,7 +84,7 @@ trait GameDef {
    * This function returns the block at the start position of
    * the game.
    */
-  def startBlock: Block = ???
+  def startBlock: Block = Block(startPos, startPos)
 
   /**
    * A block is represented by the position of the two cubes that
@@ -134,23 +134,24 @@ trait GameDef {
      * Returns the list of blocks that can be obtained by moving
      * the current block, together with the corresponding move.
      */
-    def neighbors: List[(Block, Move)] = ???
+    def neighbors: List[(Block, Move)] = List((left, Left), (right, Right), (up, Up), (down, Down))
 
     /**
      * Returns the list of positions reachable from the current block
      * which are inside the terrain.
      */
-    def legalNeighbors: List[(Block, Move)] = ???
+    def legalNeighbors: List[(Block, Move)] = neighbors filter { x => x._1.isLegal }
+                                                            // { case (block, _) => block.isLegal }
 
     /**
      * Returns `true` if the block is standing.
      */
-    def isStanding: Boolean = ???
+    def isStanding: Boolean = b1 == b2
 
     /**
      * Returns `true` if the block is entirely inside the terrain.
      */
-    def isLegal: Boolean = ???
+    def isLegal: Boolean = terrain(b1) && terrain(b2)
 
   }
 }
diff --git a/Scala/streams/src/main/scala/streams/Solver.scala b/Scala/streams/src/main/scala/streams/Solver.scala
index d6aa237..8350b50 100644
--- a/Scala/streams/src/main/scala/streams/Solver.scala
+++ b/Scala/streams/src/main/scala/streams/Solver.scala
@@ -10,7 +10,8 @@ trait Solver extends GameDef {
   /**
    * Returns `true` if the block `b` is at the final position
    */
-  def done(b: Block): Boolean = ???
+  def done(b: Block): Boolean = b == Block(goal, goal)
+                             // b.b1 == goal && b.b2 == goal
 
   /**
    * This function takes two arguments: the current block `b` and
@@ -28,7 +29,8 @@ trait Solver extends GameDef {
    * It should only return valid neighbors, i.e. block positions
    * that are inside the terrain.
    */
-  def neighborsWithHistory(b: Block, history: List[Move]): Stream[(Block, List[Move])] = ???
+  def neighborsWithHistory(b: Block, history: List[Move]): Stream[(Block, List[Move])] =
+    (b.legalNeighbors map { case (b, m) => (b, m :: history) }).toStream
 
   /**
    * This function returns the list of neighbors without the block
@@ -36,7 +38,8 @@ trait Solver extends GameDef {
    * make sure that we don't explore circular paths.
    */
   def newNeighborsOnly(neighbors: Stream[(Block, List[Move])],
-                       explored: Set[Block]): Stream[(Block, List[Move])] = ???
+                       explored: Set[Block]): Stream[(Block, List[Move])] =
+    neighbors.filter { case (block, _) => !explored.contains(block) }
 
   /**
    * The function `from` returns the stream of all possible paths
@@ -62,18 +65,24 @@ trait Solver extends GameDef {
    * construct the correctly sorted stream.
    */
   def from(initial: Stream[(Block, List[Move])],
-           explored: Set[Block]): Stream[(Block, List[Move])] = ???
+           explored: Set[Block]): Stream[(Block, List[Move])] = initial match {
+    case (block,moves) #:: xs => {
+      val  blocks = newNeighborsOnly(neighborsWithHistory(block, moves), explored)
+      (block, moves) #:: from(xs ++ blocks, explored + block)
+    }
+    case _ => Stream.empty
+  }
 
   /**
    * The stream of all paths that begin at the starting block.
    */
-  lazy val pathsFromStart: Stream[(Block, List[Move])] = ???
+  lazy val pathsFromStart: Stream[(Block, List[Move])] = from(Stream((startBlock, Nil)), Set.empty)
 
   /**
    * Returns a stream of all possible pairs of the goal block along
    * with the history how it was reached.
    */
-  lazy val pathsToGoal: Stream[(Block, List[Move])] = ???
+  lazy val pathsToGoal: Stream[(Block, List[Move])] = pathsFromStart filter { b => done(b._1) }
 
   /**
    * The (or one of the) shortest sequence(s) of moves to reach the
@@ -83,5 +92,8 @@ trait Solver extends GameDef {
    * the first move that the player should perform from the starting
    * position.
    */
-  lazy val solution: List[Move] = ???
+  lazy val solution: List[Move] = pathsToGoal match {
+    case (block, moves) #:: _ => moves.reverse
+    case _ => Nil
+  }
 }
diff --git a/Scala/streams/src/main/scala/streams/StringParserTerrain.scala b/Scala/streams/src/main/scala/streams/StringParserTerrain.scala
index 12e9a8b..e2c83d2 100644
--- a/Scala/streams/src/main/scala/streams/StringParserTerrain.scala
+++ b/Scala/streams/src/main/scala/streams/StringParserTerrain.scala
@@ -52,7 +52,10 @@ trait StringParserTerrain extends GameDef {
    * a valid position (not a '-' character) inside the terrain described
    * by `levelVector`.
    */
-  def terrainFunction(levelVector: Vector[Vector[Char]]): Pos => Boolean = ???
+  def terrainFunction(levelVector: Vector[Vector[Char]]): Pos => Boolean =
+    p => p.x >= 0 && p.y >= 0 &&
+         p.x < levelVector.length && p.y < levelVector(p.x).size &&
+         levelVector(p.x)(p.y) != '-'
 
   /**
    * This function should return the position of character `c` in the
@@ -62,7 +65,10 @@ trait StringParserTerrain extends GameDef {
    * Hint: you can use the functions `indexWhere` and / or `indexOf` of the
    * `Vector` class
    */
-  def findChar(c: Char, levelVector: Vector[Vector[Char]]): Pos = ???
+  def findChar(c: Char, levelVector: Vector[Vector[Char]]): Pos = {
+    val x = levelVector.indexWhere(_.contains(c))
+    Pos(x, levelVector(x).indexOf(c))
+  }
 
   private lazy val vector: Vector[Vector[Char]] =
     Vector(level.split("\n").map(str => Vector(str: _*)): _*)