[SOLUTION][QUIZ] Second answer for quiz 84

ruby-talk
1

After looking over my earlier answer, I realized that I had re-invented
String.center and had a number of excesses. This one is a lot smaller but I
still feel I'm not using the language to its fullest.

JB

# pp_pascal.rb
# for details, see http://www.rubyquiz.com/quiz84.html

class Pascal
  def initialize( depth )
    @d = depth
    @p = [[1]]
    1.upto(@d-1) do |row|
      @p[row] = [1]
      1.upto(row-1) do |col|
        @p[row] << (@p[row-1][col-1] + @p[row-1][col])
      end
      @p[row] << 1
    end
  end
  def show
    # the middle entry in the bottom row will have the
    # most digits - use its length as the per-entry span
    span = (@p[-1][(@d / 2).to_i].to_s.length) * 2
    width = @d * span
    rows = []
    @p.each do |p|
      ret = ''
      p.each do |i|
        ret += i.to_s.center(span)
      end
      rows << ret.center(width)
    end
    rows.join("\n")
  end
end

# default to 10 rows
rows = (ARGV[0] || 10).to_i
p = Pascal.new(rows)
puts p.show