Part (a)

Write the getEmptyLocation method that finds the empty position in the grid.

Solution

public Location getEmptyLocation()
{
    for (int r = 0; r < board.length; r++)
    {
        for (int c = 0; c < board[0].length; c++)
        {
            if (board[r][c] == 0)
            {
                return new Location(r, c);
            }
        }
    }
    return null;
}

Part (b)

Write the slideDown method that moves a tile down if the space below is empty.

Solution

public boolean slideDown(int row, int col)
{
    if (row + 1 >= board.length || board[row + 1][col] != 0)
    {
        return false;
    }
    
    board[row + 1][col] = board[row][col];
    board[row][col] = 0;
    return true;
}

Key Concepts

Common Mistakes