dynamically add different strings into an array list base on a pattern/algorithm/formula

is there a way to dynamically add this whole adding process instead of the manually entering the values like a.Add("1 & 2"); and 开发者_运维知识库so on by the way, this only happens if i select 5 conditions -i am doing the adding base on the maximum condition i cater which is 5

the subsets that i show below must be in that pattern although its ok that the order can be different but the values must be increment like (1 & 2 & 3).So jumping values like (1 & 4) is not allowed and no reverse subsets like (3 & 2)

ArrayList a = new ArrayList();
    a.Add("1 & 2");
    a.Add("2 & 3");
    a.Add("3 & 4");
    a.Add("4 & 5");
    a.Add("1 & 2 & 3");
    a.Add("2 & 3 & 4");
    a.Add("3 & 4 & 5");
    a.Add("1 & 2 & 3 & 4");
    a.Add("2 & 3 & 4 & 5");

So if i have 6 condition then the list will add on for type two subsets(5 & 6), type 3 subsets(4 & 5 & 6), ...goes on which will even create another type of subsets if possible which would be type 5(1 & 2 & 3 & 4 & 5) in this case

Any method/ways are welcome as long as the results are the same which is the arraylist will contain the whole set of subsets base on the maximum condition.

Cheers, Jaf

It sounds like you might want the power set (the set of all subsets of some given set), but from your example, it looks like you want to enumerate all sub-lists in a list using a sliding window.

If you want the power set:

Example code for generating power sets is available in this answer to a similar question.

If you want sliding window sub-lists:

You could do something like this with the code below. The example prints out exactly what you have above (using a sliding window size from 2 to 5 over the set {1, 2, 3, 4, 5}).

Note: For clarity's sake, there is no bounds-checking or error handling in the code below. There should absolutely be some.

class Program
{
    static void Main(string[] args)
    {
        foreach (var list in SlidingWindow<int>.Generate(new int[] { 1, 2, 3, 4, 5 }, 2, 5))
        {
            Console.WriteLine(string.Join(" & ", list));
        }
    }
}

static class SlidingWindow<T>
{
    static public IEnumerable<IEnumerable<T>> Generate(ICollection<T> items, int minWindowSize, int maxWindowSize)
    {
        for (int i = minWindowSize; i < maxWindowSize; ++i)
        {
            foreach (var list in Generate(items, i))
                yield return list;
        }
    }

    static public IEnumerable<IEnumerable<T>> Generate(ICollection<T> items, int windowSize)
    {
        for (int i = 0; i < (items.Count - windowSize + 1); ++i)
            yield return items.Skip(i).Take(windowSize);
    }
}