Sort an array of arrays like a snail (clockwise spiral sorting) with Ruby.

snail.rb

def snail(array)
  result = Array.new
  n = array.length
  runs = n.downto(0).each_cons(2).to_a.flatten
  delta = [[1,0], [0,1], [-1,0], [0,-1]].cycle
  x, y = -1, 0
  for run in runs
    dx,dy = delta.next
    run.times do |i|
      x += dx
      y += dy
      result << array[y][x]
    end
  end
  result
end