快速算法，用于查找字符串是否包含给定数组中的任何字符串

Question

I have a list of about 50 keywords and about 50000 strings. I check every string if it contains at least one of the keywords. I'm not interested in the matched keyword or the number of matched keywords. I only want a "true" or "false" back, as fast as possible.

So, I bet there's an algorithm out there that outperforms my current LINQ version by far:

class MyEnumerableExtension
{
    public static bool ContainsAny(this string searchString, IEnumerable<string> keywords)
    {
        return keywords.Any(keyword => searchString.Contains(keyword))
    }
}

bool foundAny = "abcdef".ContainsAny(new string[] { "ac", "bd", "cd" } );

Answer 1

这与你今天的其他问题本质上是不一样的高效算法，用于查找文本中的所有关键字，除了修改后一旦找到匹配就返回？

Answer 2

有多种算法可以在文本中搜索一组子字符串。

Answer 3

Yo可以实现Knuth-Morris-Pratt算法 。

Answer 4

A quick analysis shows that you are iteratively searching for the keywords. If you could search in one pass for all fo the keywords, you should have an overall improvement in your algorithm. A Regex expression can do that and couple it with the "Compiled" option and you should begin to see a performance increase (because it will single pass the string for all keywords). But, it would only benefit you if you have several keywords. Here's a quick idea to help you along, but note, I have not actually tested the performance against your algorithm.

        string[] keywords = { "ac", "bd", "cd" };
        string[] tosearch = { "abcdef" };
        string pattern = String.Join("|", keywords);
        Regex regex = new Regex(pattern, RegexOptions.Compiled);
        foundAny = regex.IsMatch(String.Join("|", tosearch));

Also note, this works as long as your keywords do not contain any Regex special characters (and your search strings do not contain the pipe symbol. However, the special characters could be overcome with escape sequences, and the search strings do not have to be joined as I've done.