# Takeuchi function - concurrent version

def tak(x, y, z)
  unless y < x
    z
  else
    tak(tak(x-1, y, z),
         tak(y-1, z, x),
         tak(z-1, x, y))
  end
end

def tak2(x, y, z)
  unless y < x
    z
  else
    tak2(tak2(x-1, y, z),
         tak2(y-1, z, x),
         tak2(z-1, x, y))
  end
end

require 'benchmark'

max = (ARGV.shift || 22).to_i

puts "Max: #{max}"

puts Benchmark.measure {
  threads = []
  threads << Thread.new do
    p tak(max, 9, 0)
  end

  threads << Thread.new do
    p tak2(max, 9, 0)
  end

  threads.each { |t| t.join }
}