[Level 21]

We used to play this game when we were kids
When I had no idea what to do, I looked backwards.

再加一個package.pack文件，就是[Level 21]了。沒想出來，依舊百度谷歌。

游戲指的是擊鼓傳花，我們要做的是根據數據內容判斷使用zlib或bz2解壓package.pack文件，并對每一步驟進行標記。

import zlib,bz2
f = open('package.pack','rb').read()
while True:
  if f.startswith(b'BZ'):
    f = bz2.decompress(f)
  elif f.startswith(b'x\x9c'):
    f = zlib.decompress(f)
  elif f.endswith(b'\x9cx'):
    f = f[::-1]
  else:
    break

最終解出來的數據d是b'sgol ruoy ta kool'，即look at your logs，result是copper，22關的鑰匙，[Level 22]

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