組み合わせ アルゴリズム nCk C#

using System;
using System.Collections.Generic;

public class Combination
{
    public static void Main(string[] args)
    {
        new Combination();
    }

    private Combination()
    {
        string[] data = new string[] { "A", "B", "C", "D", "E", "F" };
        int k = 3;
        List<string[]> combList = GetCombination(data, k);
        WriteComb(combList);
    }

    private List<string[]> GetCombination(string[] data, int k)
    {
        int dataIndex = 0;
        string[] combs = new string[k];
        int combsIndex = 0;
        List<string[]> combList = new List<string[]>();
        Comb(data, dataIndex, combs, combsIndex, combList);
        return combList;
    }

    private void Comb(string[] data, int dataIndex, string[] combs, int combsIndex, List<string[]> combList)
    {
        if (combsIndex == combs.Length) {
            string[] copy = new string[combs.Length];
            Array.Copy(combs, copy, combs.Length);
            combList.Add(copy);
            return;
        }

        int endDataIndex = data.Length - combs.Length + combsIndex;
        for (int i = dataIndex; i <= endDataIndex; i++) {
            combs[combsIndex] = data[i];
            Comb(data, i + 1, combs, combsIndex + 1, combList);
        }
    }

    private void WriteComb(List<string[]> combList)
    {
        int n = 1;
        foreach (string[] combs in combList) {
            Console.WriteLine(string.Format("{0}: {1}", n, string.Join(",", combs)));
            n++;
        }
    }
}