c# - 从 C# 中的重复字符串中确定唯一字符串

Question

我需要开发一种有效的算法来确定给定具有重复内容(并且仅重复内容)的字符串的唯一(重复)字符串...

例如:

“AbcdAbcdAbcdAbcd” => “Abcd”

“你好” => “你好”

我在想出一个相当有效的算法时遇到了一些麻烦；任何意见将不胜感激。

澄清:我想要最短的字符串，当重复足够多次时，它等于总字符串。

Answer 1

    private static string FindShortestRepeatingString(string value)
    {
        if (value == null) throw new ArgumentNullException("value", "The value paramter is null.");

        for (int substringLength = 1; substringLength <= value.Length / 2; substringLength++)
            if (IsRepeatingStringOfLength(value, substringLength))
                return value.Substring(0, substringLength);
        return value;
    }

    private static bool IsRepeatingStringOfLength(string value, int substringLength)
    {
        if (value.Length % substringLength != 0)
            return false;
        int instanceCount = value.Length / substringLength;
        for (int characterCounter = 0; characterCounter < substringLength; characterCounter++)
        {
            char currentChar = value[characterCounter];
            for (int instanceCounter = 1; instanceCounter < instanceCount; instanceCounter++)
                if (value[instanceCounter * substringLength + characterCounter] != currentChar)
                    return false;
        }
        return true;
    }