bwinf.de 2010/2011 2nd round, ex. 3

traumdreieck.rb

puts "bwinf.de 2010/2011 2nd round, ex. 3"
puts "Copyright (c) Jannik Schuerg 2011, GPLv3"
puts
if ARGV[0] =~ /[1-9]\d*/
  n = ARGV[0].to_i
else
  puts "Usage: traumdreieck.rb <number of levels>"
end

conditions = []

def first_ball_number_on_level(level)
  (2 + level + level ** 2) / 2
end

n.times do |level|
  balls = level + 1
  first_num = first_ball_number_on_level(level)
  first_num.upto(first_num + balls - 1) do |ball|
    (level + 1).upto(n - 1) do |child_level|
      ball_a = first_ball_number_on_level(child_level) + (ball - first_num)
      ball_b = ball_a + (child_level - level)
      conditions << [ball_a, ball_b, ball]
    end
  end
end

ball_colors = {}

color_counter = 1
ball_colors[1] = color_counter

def rand_choose(a, b) rand(2) == 1 ? a : b end

conditions.each do |condition| a, b, ball = *condition
  ca, cb = ball_colors[a], ball_colors[b]
  next if ca && cb
  look_at = !ca && !cb ? rand_choose(a, b) : (ca ? b : a)
  conditons_for_it = conditions.
    find_all { |e| e[0] == look_at || e[1] == look_at }.map { |e| e[2] }.
    find_all { |e| not ball_colors[e].nil? }.map { |e| ball_colors[e] }
  if conditons_for_it.empty?
    ball_colors[look_at] = rand(color_counter) + 1
  elsif conditons_for_it.length == color_counter
    color_counter += 1
    ball_colors[look_at] = color_counter
  else
    cond_color = conditons_for_it[rand(conditons_for_it.length)]
    begin
      ball_colors[look_at] = rand(color_counter) + 1
    end while ball_colors[look_at] == cond_color
  end
end

(n*(n+1)/2).times do |ball|
  next if ball_colors[ball + 1]
  ball_colors[ball + 1] = rand(color_counter) + 1
end

max = n.to_s.length

n.times do |level|
  start = first_ball_number_on_level(level)
  stop = start + level
  line = []
  start.upto(stop) { |i| line << ball_colors[i].to_s.center(max) }
  puts ' ' * (n - level) * max + line.join(' ' * max)
end

puts