pascal.rb

triangle = Enumerator.new do |e|
  arr = [1]
  loop do
    e << arr.join(" ")
    arr = [1, *arr.each_cons(2).map { |x| x.inject(:+) }, 1]
  end
end

while (depth = gets.to_i) > 0
  lines = triangle.take(depth)
  just = lines.last.length
  puts lines.map { |l| l.center(just) }
end