PythonChallenge —— 3（关卡）

import string
import re

text = open('info.txt').read()
text = str(text)
pattern = re.findall(r'[a-z]{1}[A-Z]{3}([a-z]{1})[A-Z]{3}[a-z]{1}',text)
print(''.join(pattern))

结果：

linkedlist