Calculating all possible sub-sequences of a given length (C#)

Question

If I have a sequence as follows (let\'s say it\'s an IEnumerable):

[A, B, C, D, E]

Then what\'s the cleanest way to c

Answer 1

Something like:

static void Main()
{
    string[] data = { "A", "B", "C", "D", "E" };
    WalkSubSequences(data, 3);
}

public static void WalkSubSequences(IEnumerable data, int sequenceLength)
{
    T[] selected = new T[sequenceLength];
    WalkSubSequences(data.ToArray(), selected, 0, sequenceLength);
}
private static void WalkSubSequences(T[] data, T[] selected,
    int startIndex, int sequenceLength)
{
    for (int i = startIndex; i + sequenceLength <= data.Length; i++)
    {
        selected[selected.Length - sequenceLength] = data[i];
        if (sequenceLength == 1)
        {
            ShowResult(selected);
        }
        else
        {
            WalkSubSequences(data, selected, i + 1, sequenceLength - 1);
        }
    }
}

private static void ShowResult(T[] selected)
{
    StringBuilder sb = new StringBuilder();
    sb.Append(selected[0]);
    for (int j = 1; j < selected.Length; j++)
    {
        sb.Append(';').Append(selected[j]);
    }
    Console.WriteLine(sb.ToString());
}