Solution: Zeta Mazes

require "cell"
require "grid"
require "recursive_backtracker"
class ZetaCell < Cell
  #Your code goes here
  attr_accessor :nw, :ne, :sw, :se
  def neighbors
    super.tap do |list|
      [ nw, ne, sw, se ].each do |neighbor|
        list << neighbor if neighbor && can_link_to?(neighbor)
      end
    end
  end
  # this is where we check to see if the shared neighbors are already
  # connected diagonally, in which case we disallow a link to the cell.
  def can_link_to?(cell)
    if north && cell.west == north
      !north.linked?(north.se)
    elsif north && cell.east == north
      !north.linked?(north.sw)
    elsif south && cell.west == south
      !south.linked?(south.ne)
    elsif south && cell.east == south
      !south.linked?(south.nw)
    else
      true
    end
  end
end
class ZetaGrid < Grid
  def prepare_grid
    Array.new(rows) do |row|
      Array.new(columns) do |col|
        ZetaCell.new(row, col)
      end
    end
  end
  def configure_cells
    each_cell do |cell|
      row, col = cell.row, cell.column
      cell.north = self[row - 1, col]
      cell.south = self[row + 1, col]
      cell.west  = self[row, col - 1]
      cell.east  = self[row, col + 1]
      cell.nw    = self[row - 1, col - 1]
      cell.ne    = self[row - 1, col + 1]
      cell.sw    = self[row + 1, col - 1]
      cell.se    = self[row + 1, col + 1]
    end
  end
  def to_png(cell_size: 10)
    # add a margin around the maze, so the lines at the edges
    # are easier to see
    img_width = cell_size * (columns + 1)
    img_height = cell_size * (rows + 1)
    background = ChunkyPNG::Color::WHITE
    passage    = ChunkyPNG::Color::BLACK
    img = ChunkyPNG::Image.new(img_width, img_height, background)
    each_cell do |cell|
      x = (cell.column + 1) * cell_size
      y = (cell.row + 1) * cell_size
      [ cell.ne, cell.east, cell.se, cell.south ].each do |neighbor|
        if cell.linked?(neighbor)
          x2 = (neighbor.column + 1) * cell_size
          y2 = (neighbor.row + 1) * cell_size
          # draw the passage between the two cells as a single line
          img.line x, y, x2, y2, passage
        end
      end
    end
    img
  end
end
grid = ZetaGrid.new(10, 10)
RecursiveBacktracker.on(grid)
img = grid.to_png
img.save "zeta.png"
filename="zeta.png"
grid.to_png.save("/usercode/output/"+filename)