最长子串 可以使用 difflib

longestsubstring.py

def longest_substring(str1, str2):
    """
    >>> longest_substring("apple pie available", "apple pies")
    'apple pie'
    >>> longest_substring("apples", "appleses")
    'apples'
    >>> longest_substring("bapples", "cappleses")
    'apples'
    """
    result = ""
    len1, len2 = len(str1), len(str2)
    for i in range(len1):
        match = ""
        for j in range(len2):
            if (i + j < len1 and str1[i + j] == str2[j]):
                match += str2[j]
            else:
                if (len(match) > len(result)):
                    result = match
                match = ""
    return result


if __name__ == '__main__':
    import doctest
    doctest.testmod(verbose=False)