检查字符串是否是未知子字符串的重复

问题描述：

我正在尝试编写一个正则表达式或 Ruby 方法，它会在字符串中找到最长的重复模式.例如:

I'm trying to write a regex or Ruby method which will find the longest repeated pattern in a string. For example:

"abcabc"  => "abc"  
"cccc" => "c"
"abcd" => "abcd"

实现此目的的最佳方法是什么?我天真地尝试了 /^(.*)*$/ 但这不起作用，因为它只匹配完整的字符串.

What is the best way to implement this? I naïvely tried /^(.*)*$/ but that won't work as it just matches the full string.

答

我知道事情不会那么复杂，所以我想了想，找到了一个解决方案:

I knew it couldn't be that complicated, so I thought it over and found a solution:

def unrepeat(str)
  n = str.size

  newstr = str
  n.times do |i|
     newstr = newstr[-1] + newstr[0..-2]
     if newstr == str
        return i + 1
     end
  end
end

这将返回重复模式的长度.它通过生成字符串的旋转来找到它.

This will return the length of the repeated pattern. It finds this by generating rotations of the string.

检查字符串是否是未知子字符串的重复

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