最长重复子串 [英] Longest repeated substring

问题描述

在我去上学的同时学习 Python.本质上，我需要在字符串列表中找到最长的重复子字符串，如这篇文章，并对我应该做的事情有所了解.

learning python as I go for school work. Essentially, I need to find the longest repeated substring in a list of string as shown here. I have been reading through this article and have an understanding of what I should do.

到目前为止，我的实现如下:

so far my implementation is as follows:

def long_rptr_subString(testList):
    longSubstring = ''

    if len(testList) > 1 and len(testList[0]) > 0:
        for i in range(len(testList[0])):
            for j in range(len(testList[0])-i+1):
                if j > len(longSubstring) and all(testList[0][i:i+j] in x for x in testList):
                    longSubstring = testList[0][i:i+j]
    return longSubstring

现在当我用 ['slide'，'glidb'，'flidt'，'cridz'，'bidr'] 调用函数时作为我最长的子字符串，我得到了'id'的正确结果.

now when I call my function with let's say ['slide', 'glidb', 'flidt', 'cridz', 'bidr'] I get the correct result of 'id' as being my longest substring.

但是，当我通过列表 ['slide'，'glidb'，'flidt'，'cridz'，'bidr'，'balh'，'tejka'，'djakljskdl'，'blah'，'等等'，我没有得到任何返回结果.我应该取回'blah'作为我最长的子字符串，但是我还没有找到实现此目的的方法.看来我只能在列表的所有项目中都匹配子字符串.如何修改代码/逻辑以获取出现多次的最长子字符串?

However, when I pass the list ['slide', 'glidb', 'flidt', 'cridz', 'bidr', 'balh', 'tejka', 'djakljskdl', 'blah', 'blah', 'blah'] I don't get any return results. I should be getting back 'blah' as my longest substring, but I haven't figured out a way to accomplish this. It seems I am only able to match substrings when they are in ALL items of the list. How might I modify my code/logic to get the longest substring that occurs more than once?

谢谢.

推荐答案

您只能匹配 all 项目中的子字符串，因为这正是您要的:

You can only match substrings in all items because that's exactly what you ask for:

all(testList[0][i:i+j] in x for x in testList)

即使您进行了更改，也只能找到 first 子字符串中最长的子字符串，因为您只能通过 testlist [0] 进行检查.

Even if you change that, you can only find the longest substring that is in the first substring, because you only check through testlist[0] .

相反，请尝试以下操作:

Instead, try something like:

def longest_substr(lst):
    longest = None
    for word in lst:
        for i in range(len(word)):
            for j in range(i+1, len(word)+1):
                if ((longest is None or (j - i > len(longest))) and
                    sum(word[i:j] in w for w in lst) > 1):
                    longest = word[i:j]
    return longest

这会找到至少两个(> 1 )个单词中最长的子字符串(或者对于空列表或空字符串列表，不返回)并给出以下结果:

This finds the longest substring that's in at least two (> 1) of the words (or will return None for an empty list or list of empty strings) and gives me the following results:

>>> longest_substr(['slide', 'glidb', 'flidt', 'cridz', 'bidr'])
'lid'
>>> longest_substr(['slide', 'glidb', 'flidt', 'cridz', 'bidr', 'balh', 'tejka', 'djakljskdl', 'blah', 'blah', 'blah'])
'blah'

请注意，一旦删除了必须在所有字符串中包含子字符串的要求，则第一个单词列表中最长的实际上就是'lid'.

Note that, once you remove the requirement that the substring must be in all strings, the longest in your first list of words is actually 'lid'.

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