Code IQ チケットゴブル問題

ticketgobble.rb

#! /usr/bin/ruby -w
# encoding: utf-8

require 'date'

class Ticket
  def initialize(string)
    @nation, term = string.split
    @departure, @arrival = term.split(/-/).map { |e| Date.parse("2012/" + e) }
    @trip_num = 1
    @next = nil
  end

  def to_str
    @departure.to_s + " - " + @arrival.to_s + "\t" + @nation
  end

  def add_trip(ticket)
    @next = ticket
    @trip_num += ticket.trip_num
  end

  attr_reader:nation, :departure, :arrival, :next, :trip_num
end

def show_continuous(ticket)
  print ticket.to_str
  print "\n"
  if !ticket.next.nil?
    print show_continuous(ticket.next)
  end
end

def show_answer(max_ticket)
  tickets = []
  tickets << max_ticket.nation
  next_ticket = max_ticket.next
  while !next_ticket.nil?
    tickets << next_ticket.nation
    next_ticket = next_ticket.next
  end
  tickets = tickets.sort
  print tickets.length()
  tickets.each do |t|
    print " "
    print t
  end
end


#チケットをファイルから読んで到着順に並べ替える
tickets = []
ARGF.each do |line|
  obj = Ticket.new(line.chomp)
  tickets << obj
end
tickets.sort! { |a, b| a.arrival <=> b.arrival  }

last_max = tickets.size() -1
ticket_idx = tickets.size() -1

#到着順にチェック
while 0 <= ticket_idx
  ticket = tickets[ticket_idx]
  chk_idx = ticket_idx

  max_num = 0
  max_ticket = nil
  max_chk = last_max
  trip_num = 0

  # 到着日に対する最長のチケットまで調べる．
  #
  #         ------ <----------- check
  #       --------- 1
  #         -------- 1
  # ~~~~~~~~~~~~~~~~~~~~~~~~~~~
  #            -------- 1
  #                ------ 2  <- ここまで調べればOK
  #              ----------- 1
  #                        -- 1
  #
  while chk_idx <= last_max
    jticket = tickets[chk_idx]
    if ticket.arrival < jticket.departure
      trip_num = jticket.trip_num
      if max_num < trip_num
        max_num = trip_num
        max_ticket = jticket
        max_jdx = chk_idx
      end
    end
    chk_idx = chk_idx + 1
  end

  if !max_ticket.nil?
    ticket.add_trip(max_ticket)
    last_max = max_chk
  end
  ticket_idx = ticket_idx - 1
end

max_trip = tickets.max_by{|c| c.trip_num}
#show_continuous(max_trip)
show_answer(max_trip)