kern f

points on a circle

Before I get completely rusty with LaTeX, here's another one in the series of absurdly trivial papers: this one derives a program that establishes if there are 4 points from a set of points on a circle that form a rectangle.

bridge hands in ruby

A little while ago I started looking at Ruby and Ruby on Rails. So far I like what I see. I'm doing a little address book app to try rails and for the ruby side I'm solving pretty much random finger exercises like this one: bridge hands.

#!/usr/local/bin/ruby -w

require "enumerator"

Card = Struct.new(:suit, :face)

IS_PLAYER = /^[SWNE]$/
IS_CARDS = /^([CDSH][2-9TJQKA])+$/

PLAYERS = %w{S W N E}
SUITS = %w{C D S H}
FACES = %w{2 3 4 5 6 7 8 9 T J Q K A}

deck = nil
dealer = 0

ARGF.each_line() do |line|
  line.chomp!
  next if line.empty?
  case line
  when IS_PLAYER
    deck = Array.new
    dealer = PLAYERS.index(line)
  when IS_CARDS   
    deck.concat( 
       line.enum_for(:each_byte).enum_slice(2).map do |sf|
           Card.new(sf[0], sf[1])
       end)
    if deck.size == 52 then
      # process deck
      hands = PLAYERS.inject(Hash.new) do |map, player| 
        map[player]= Array.new
        map
      end
      deck.enum_slice(4).each do |round|
        (0...4).each do |num| 
          hands[PLAYERS[(dealer + num + 1) % 4]] << round[num]
        end  
      end 
      PLAYERS.each do |player| 
        hands[player] = hands[player].sort_by do |card|
          SUITS.index(card.suit.chr) * FACES.size + 
             FACES.index(card.face.chr)
        end  
        puts hands[player].inject(player + ":") { |string, card|
           string + " " + card.suit.chr + card.face.chr
        }    
      end          
    end
  when "\#"
    Kernel.exit(0)
  else
    Kernel.exit(1)
  end    
end  

I'm still new in this ruby world so if you see some ruby idiom I'm missing or some awkward antipattern that I use feel free to correct me in comments.