These

twentyfortyeight/src/twentyfortyeight/Main.java

@@ -37,9 +37,10 @@ class Util {
     // Convert a movement to a displacement vector.
     static Coord moveDisp(Move move) {
         if (move.equals(Move.LEFT)) return new Coord(-1, 0);
-        else if (move.equals(Move.DOWN)) return new Coord(0, -1);
-        else if (move.equals(Move.UP)) return new Coord(0, 1);
-        else return new Coord(0, 1);
+        else if (move.equals(Move.DOWN)) return new Coord(0, 1);
+        else if (move.equals(Move.UP)) return new Coord(0, -1);
+        else if (move.equals(Move.RIGHT)) return new Coord(1, 0);
+        else return null;
     }
 }
 
@@ -85,9 +86,6 @@ class Game extends World {
     void run() { this.bigBang(this.width, this.width, 0.01); }
 }
 
-// The possible movements.
-enum Move { UP, LEFT, RIGHT, DOWN }
-
 // The board on which the game is played.
 class Board {
     int sz; // The side length of the board grid square.
@@ -150,13 +148,12 @@ class Board {
     // Move cell as much as possible.
     void fullCellMove(Coord coord, Move move) {
         Cell cell = this.get(coord);
-        Coord current = coord;
+        Coord disp = Util.moveDisp(move);
 
         if (!cell.isMoveable()) return;
 
-        while (this.get(current.add(Util.moveDisp(move))).isReplaceable()) {
-            this.tryCellMove(current, current.add(Util.moveDisp(move)));
-            current = current.add(Util.moveDisp(move));
+        for () {
+            this.tryCellMove(coord, coord.add(disp));
         }
     }
 
@@ -177,8 +174,8 @@ class Board {
         }
 
         else if (move.equals(Move.RIGHT)) {
-            for (int x = 0; x < this.sz - 1; x++) {
-                this.tryCellMove(new Coord(x, i), new Coord(x + 1, i));
+            for (int x = this.sz - 2; x >= 0; x--) {
+                this.fullCellMove(new Coord(x, i), move);
             }
         }
 
@@ -190,6 +187,9 @@ class Board {
     }
 }
 
+// The possible movements.
+enum Move { UP, LEFT, RIGHT, DOWN }
+
 // A cell on the board.
 abstract class Cell {
     // Generate the color of the tile.
@@ -204,7 +204,7 @@ abstract class Cell {
 
     // Is this moveable?
     boolean isMoveable() { return false; }
-    boolean isReplaceable() { return true;}
+    boolean isReplaceable() { return false;}
 }
 
 // A moveable tile on the board.
@@ -234,6 +234,7 @@ class Tile extends Cell {
 // An empty space on the board.
 class Space extends Cell {
     Color col() { return Color.LIGHT_GRAY; }
+    boolean isReplaceable() { return true; }
 }
 
 // Board coordinates.