code: public static String getPrettyPath(List<Puzzle> path, int size) {
          // Print each row of all states
          StringBuffer output = new StringBuffer();
          for (int y = 0; y < size; y++) {
              String row = "";
              for (Puzzle state : path) {
                  int[][] board = state.getMatrixBoard();
                  row += "| ";
                  for (int x = 0; x < size; x++) {
                      row += board[y][x] + " ";
                  }
                  row += "|  ";
              }
              row += "\n";
              output.append(row);
          }
          return output.toString();
      }
docs: Prints a search path in a readable form.
  
  @param path List of puzzle states of the path.
  @param size Size of the puzzle state (8 for 8-puzzle)
  @return String representing all the transitions from initial to goal.