Question

I have a string such as “big bad dog”, how can I get an string[] array which includes all the possible word/phrase combinations?

So, I would like to return “big”, “bad”, “dog”, “big bad”, “bad dog” and “big bad dog” – therefore the order of the words in the original string must be respected.

Is this something that could be done with a regular expression?

Answer 1

I think this is a nice problem to solve recursively. My take:

public static String[] findWords(params string[] args)
{

        if (args.Count() == 0)
        {
            return new String[] { "" };
        }
        else
        {
            String[] oldWords = findWords(args.Skip(1).ToArray());
            String[] newWords = oldWords.Where(word => word == "" || word.Split(new String[] { " " }, StringSplitOptions.RemoveEmptyEntries)[0] == args[1])
                                        .Select(word => (args[0] + " " + word).Trim()).ToArray();

            return oldWords.Union(newWords).ToArray();
        }
} 

A findWords("big", "bad", "dog") returns your list of phrases.

Edit: Edited to only include consecutive phrases.