codeiq863.py

# -*- coding: utf-8 -*-
import re

def find_greedy(plans):
  if len(plans)==0: return []

  plans.sort(key=lambda x: x[3]) # 終了時間でソート
  next_plan = plans[0]           # (残った中で)一番早く終わるチケットを選択

  result = [next_plan]
  result.extend(find_greedy(filter(lambda x: x[2] > next_plan[3], plans)))
  return result

# initialize
plans = []
p = re.compile('([a-zA-Z]+) ([0-9]+)/([0-9]+)-([0-9]+)/([0-9]+)')
for i,line in enumerate(open('tickets.txt')):
  m = p.match(line)
  plans.append((i, m.group(1), int(m.group(2))*100+int(m.group(3)), int(m.group(4))*100+int(m.group(5)))) # ソートしやすいように日付を数値化

# solve
ans = find_greedy(plans)
ans.sort(key=lambda x:x[0])

# output
out = str(len(ans))
for a in ans:
  out += ' ' + a[1]
open('answer.txt', 'w').write(out)