Listing all permutations of a string/integer

Question

A common task in programming interviews (not from my experience of interviews though) is to take a string or an integer and list every possible permutation.

Is there

Answer 1

It's just two lines of code if LINQ is allowed to use. Please see my answer here.

EDIT

Here is my generic function which can return all the permutations (not combinations) from a list of T:

static IEnumerable>
    GetPermutations(IEnumerable list, int length)
{
    if (length == 1) return list.Select(t => new T[] { t });

    return GetPermutations(list, length - 1)
        .SelectMany(t => list.Where(e => !t.Contains(e)),
            (t1, t2) => t1.Concat(new T[] { t2 }));
}

Example:

IEnumerable> result =
    GetPermutations(Enumerable.Range(1, 3), 3);

Output - a list of integer-lists:

{1,2,3} {1,3,2} {2,1,3} {2,3,1} {3,1,2} {3,2,1}

As this function uses LINQ so it requires .net 3.5 or higher.