Dr. Mario: placement viruses

placement.rb

# coding: utf-8

WIDTH  = 8
HEIGHT = 16

$field = Array.new(WIDTH).map{Array.new(HEIGHT, :none)}

def cell(x, y, offset_x = 0, offset_y = 0)
  _x = x + offset_x
  _y = y + offset_y

  return :none if _x < 0 or _x >= WIDTH
  return :none if _y < 0 or _y >= HEIGHT

  $field[_x][_y]
end


def placeable?(x, y, virus)
  return false if $field[x][y] != :none
  x_len = y_len = 0

  for i in -2..2
    x_len += 1
    y_len += 1
    x_len = 0 if cell(x, y, i, 0) != virus and i != 0
    y_len = 0 if cell(x, y, 0, i) != virus and i != 0

    return false if x_len >= 3 or y_len >= 3
  end

  true
end


def put_virus(margin)
  r = Random.new()
  x = r.rand(WIDTH)
  y = r.rand(margin..HEIGHT)
  virus = [:red, :blue, :yellow].sample

  if placeable?(x, y, virus)
    $field[x][y] = virus
    return true
  end

  false
end

def draw()
  characters = {
    :none   => "　",
    :red    => "◯",
    :blue   => "●",
    :yellow => "◎",
  }

  for y in 0...HEIGHT
    for x in 0...WIDTH
      print characters[cell(x, y)]
    end
    puts
  end
end

level = 16

num_viruses = 4 * (level + 1)
margin = 6
margin = 5 if level >= 15
margin = 4 if level >= 17

i = 0
while i < num_viruses do
  i += 1 if put_virus(margin)
end

draw