added TextDisplay and GraphicsDisplay

src/magic_squares/MagicSquareSolver.scala

@@ -1,6 +1,6 @@
 package magic_squares
 
-class MagicSquareSolver(initialGrid: Grid) {
+abstract class MagicSquareSolver(initialGrid: Grid) extends Displayable {
   protected var _initial: Grid = initialGrid
   protected val _size: Int = _initial.length
   protected val SUM: Int = 15
@@ -28,6 +28,7 @@ class MagicSquareSolver(initialGrid: Grid) {
   private def solveFrom(grid: Grid, x: Int, y: Int): Option[Grid] = {
     if (DEBUG) println(s"Solving from $x, $y")
     if (DEBUG) print(grid)
+    display(grid)
     if (!isValid(grid)) {
       if (DEBUG) println("  Grid is invalid")
       return None
@@ -111,7 +112,7 @@ object MagicSquareSolver {
       Array(8, 0, 0),
       Array(0, 0, 7),
       Array(0, 9, 0)
-    ))
+    )) with TextDisplay
     solver1.solve()
     println()
     /*
@@ -124,7 +125,7 @@ object MagicSquareSolver {
       Array(9, 0, 0),
       Array(0, 0, 7),
       Array(0, 8, 0)
-    ))
+    )) with TextDisplay
     solver2.solve()
     println()
     /*
@@ -135,7 +136,7 @@ object MagicSquareSolver {
       Array(0, 0, 2),
       Array(0, 5, 7),
       Array(0, 0, 0)
-    ))
+    )) with GraphicsDisplay
     solver3.solve()
     /*
     4,9,2