Getting all possible combinations from a list of numbers

Question

I\'m looking for an efficient way to achieve this:

• you have a list of numbers 1.....n (typically: 1..5 or 1..7 or so - reasonably small, but can vary from c

Answer 1

This is something I have written in the past to accomplish such a task.

List CreateSubsets(T[] originalArray) 
{ 
    List subsets = new List(); 

    for (int i = 0; i < originalArray.Length; i++) 
    { 
        int subsetCount = subsets.Count; 
        subsets.Add(new T[] { originalArray[i] }); 

        for (int j = 0; j < subsetCount; j++) 
        { 
            T[] newSubset = new T[subsets[j].Length + 1]; 
            subsets[j].CopyTo(newSubset, 0); 
            newSubset[newSubset.Length - 1] = originalArray[i]; 
            subsets.Add(newSubset); 
        } 
    } 

    return subsets; 
}

It's generic, so it will work for ints, longs, strings, Foos, etc.