import java.util.Random;
import java.util.Scanner;

/////////////////////////////////////////////////////////////////////////////////////////
// Add code only at the positions indicated below by the comments, leaving the rest of //
// the code untouched. Do not import any additional classes beyond the ones provided.  //
/////////////////////////////////////////////////////////////////////////////////////////

public class Puzzle {

    private final int SIZE = 4;
    public static final int UP = 8;
    public static final int DOWN = 2;
    public static final int LEFT = 4;
    public static final int RIGHT = 6;

    /////////////////////////////////////////////
    // ADD APPROPRIATE INSTANCE VARIABLES HERE //
    /////////////////////////////////////////////

    /////////////////////////////////////////
    // ADD AN APPROPRIATE CONSTRUCTOR HERE //
    /////////////////////////////////////////
    
    public String get(int row, int col) {
        return "" + (grid[row][col] == 16 ? " " : "" + grid[row][col]);
    }

    public boolean isSolved() {

        ////////////////////////////////////////////////
        // ADD CODE HERE SO THAT THIS METHOD.         //
        // RETURNS true WHEN THE PUZZLE IS "IN ORDER" //
        ////////////////////////////////////////////////

    }

    public void slide(int direction) {

        //////////////////////////////////////////////
        // ADD CODE HERE TO CHANGE THE STATE OF THE //
        // PUZZLE IN ACCORDANCE TO SLIDING A TILE   //
        // UP, DOWN, LEFT, OR RIGHT AS POSSIBLE AND //
        // IN ACCORDANCE WITH THE CONSTANTS DEFINED //
        // ABOVE                                    //
        //////////////////////////////////////////////

    }
    
    public void shuffle() {
        
        ////////////////////////////////////////////
        // ADD CODE HERE TO SHUFFLE THE PUZZLE BY //
        // TRYING TO SLIDE A TILE INTO THE SPACE  //
        // FROM A RANDOM DIRECTION 1000 TIMES     //
        ////////////////////////////////////////////

    }
    
    public String toString() {
        String s = "";
        for (int r = 0; r < SIZE; r++) {
            for (int c = 0; c < SIZE; c++) {
                int num = grid[r][c];
                s += (num < 10 ? " " : "") + (num == 16 ? " X" : num) + " ";
            }
            s += System.lineSeparator();
        }
        return s;
    }

    public static void main(String[] args) {
        Puzzle puzzle = new Puzzle();
        System.out.println("The goal is to get the numbers in the grid in order, with the (open) X in the bottom right");
        System.out.println("Enter 2, 4, 8, and 6 to slide a tile down, left, up, or right, into the open X");
        System.out.println("Repeat as needed, to solve the puzzle.");
        System.out.println(puzzle);

        // these are a couple slides to shuffle it "just a little" so that you can quickly solve it
        // feel free to add more slides to test the other directions
        puzzle.slide(LEFT);
        puzzle.slide(UP);

        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            int direction = scanner.nextInt();
            if (direction == 0) break; // which ends the program
            puzzle.slide(direction);
            if (puzzle.isSolved()) System.out.println("YOU SOLVED IT!");
            System.out.println(puzzle);
        }
    }
}