From: John Baylor <john.baylor@...>
Date: 2006-12-13T06:07:00+09:00
Subject: Quiz 105 Solution - now with Trees!

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Its not quite as clean as I'd like but there are other things I should be
doing...

class Tournament
  attr_reader :list

  def initialize players
    raise "Must be more than one player in the tournament!" if players < 2
    @players = players
    @list = Array.new(players) { |i| i+1 }

    # Add 'bye's up to the next power of 2
    next_power = 2 ** sprintf("%b",players).length
    unless players == next_power / 2
      (players+1).upto(next_power) { @list << 'bye' }
    end
    @list = generate @list
  end

  def generate list
    len = list.length
    return list if len <= 2
    left = list[0..(len/4-1)]+list[-(len/4)..-1]
    right= list[(len/4)..-(len/4+1)]
    [generate(left),generate(right)]
  end

  def to_s
    lines = []
    depth = sprintf("%b",@list.flatten.length).length - 1
    title = ""
    1.upto(depth) { |r| title += sprintf( "R%d  ", r ) }
    lines << title
    lines << ("=" * title.length)
    lines << to_a(@list)
    lines.join("\n")
  end

  # recursively build the tree display
  def to_a list = @list
    lines = []
    return lines if list.length < 2
    if list[0].is_a? Array
      left  = to_a(list[0]).flatten
      right = to_a(list[1]).flatten
      indent = (left + right).collect { |i| i.length }.max
      all = left[0..(left.length / 2)]
      left[(left.length / 2 + 1)..-1].each do |i|
        all << ((i + (" "*indent))[0..(indent-1)] + "|")
      end
      all << (" "*indent) + "|---"
      right[0..(right.length / 2 - 1)].each do |i|
        all << ((i + (" "*indent))[0..(indent-1)] + "|")
      end
      all << right[(right.length / 2)..-1]
    else
      return [list[0].to_s, "---", "   |---", "---", list[1].to_s]
    end
  end
end

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