What's a good way for figuring out all possible words of a given length

Question

I\'m trying to create an algorithm in C# which produces the following output strings:

AAAA
AAAB
AAAC
...and so on...
ZZZX
ZZZY
ZZZZ

What is the

Answer 1

There's always the obligatory LINQ implementation. Most likely rubbish performance, but since when did performance get in the way of using cool new features?

var letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();

var sequence = from one in letters
               from two in letters
               from three in letters
               from four in letters
               orderby one, two, three, four
               select new string(new[] { one, two, three, four });

'sequence' will now be an IQueryable that contains AAAA to ZZZZ.

Edit:

Ok, so it was bugging me that it should be possible to make a sequence of configurable length with a configurable alphabet using LINQ. So here it is. Again, completely pointless but it was bugging me.

public void Nonsense()
{
    var letters = new[]{"A","B","C","D","E","F",
                        "G","H","I","J","K","L",
                        "M","N","O","P","Q","R","S",
                        "T","U","V","W","X","Y","Z"};

    foreach (var val in Sequence(letters, 4))
        Console.WriteLine(val);
}

private IQueryable Sequence(string[] alphabet, int size)
{
    // create the first level
    var sequence = alphabet.AsQueryable();

    // add each subsequent level
    for (var i = 1; i < size; i++)
        sequence = AddLevel(sequence, alphabet);

    return from value in sequence
           orderby value
           select value;
}

private IQueryable AddLevel(IQueryable current, string[] characters)
{
    return from one in current
           from character in characters
           select one + character;
}

The call to the Sequence method produces the same AAAA to ZZZZ list as before but now you can change the dictionary used and how long the produced words will be.