Question

I’m learning C# by reading a books and other online tutorials (homeandlearn.co.uk)

I’ve managed to do the FizzBuzz excercise but struggling with the below excercise. Any help would be much much appreciated.

Please explain in detail so i can learn aswell.

Excercise

filter a list of strings that should pass only six letter strings that are composed of two concatenated smaller strings that are also in the list.

For example, given the list

acks, top, cat, gr, by, bar,lap, st, ely, ades

The list should return

stacks, laptop, grades, barely

Because these are a concatenation of two other strings:

st + acks = stacks

lap + top = laptop

gr + ades = grades

bar + ely = barely

Answer 1

There really are a lot of ways to do this. Here’s one that uses pairing:

        //grab all possible pairings in one data structure
        List<KeyValuePair<string, string>> pairs = new List<KeyValuePair<string, string>>();
        string[] list = { "acks", "top", "cat", "gr", "by", "bar", "lap", "st", "ely", "ades" };
        foreach (string first in list)
        {
            foreach (string second in list)
            {
                pairs.Add(new KeyValuePair<string, string>(first, second));
            }
        }

        //test each pairing for length and whatever else you want really
        List<string> sixLetterWords = new List<string>();
        foreach (KeyValuePair<string, string> pair in pairs)
        {
            string testWord = pair.Key + pair.Value;
            if (testWord.Length == 6)
            {
                sixLetterWords.Add(testWord);
            }
        }