Words combinations without repetition

Question

I have 10 words. How can I get all possible combinations of 5 words (n=10, k=5). The order does not matter.

For example: \"A\",

Answer 1

public IActionResult Index() 
{
    var list = new List { "a", "b", "c", "d", "e" };
    List ret = GetAllCombinations(list).OrderBy(_ => _).ToList();

    return View();
}

static IEnumerable GetAllCombinations(IEnumerable list)
{
    return list.SelectMany((mainItem, mi) => list.Where((otherItem, oi) => mi < oi)
                              .Select(otherItem => mainItem + otherItem));
}

Ouput ret:

ab
ac
ad
ae
bc
bd
be
cd
ce
de