How would you calculate all possible permutations of 0 through N iteratively?

Question

I need to calculate permutations iteratively. The method signature looks like:

int[][] permute(int n)

For n = 3 for example, the r

Answer 1

Below is my generics version of the next permutation algorithm in C# closely resembling the STL's next_permutation function (but it doesn't reverse the collection if it is the max possible permutation already, like the C++ version does)

In theory it should work with any IList<> of IComparables.

    static bool NextPermutation(IList a) where T: IComparable
    {
        if (a.Count < 2) return false;
        var k = a.Count-2;

        while (k >= 0 && a[k].CompareTo( a[k+1]) >=0) k--;
        if(k<0)return false;

        var l = a.Count - 1;
        while (l > k && a[l].CompareTo(a[k]) <= 0) l--;

        var tmp = a[k];
        a[k] = a[l];
        a[l] = tmp;

        var i = k + 1;
        var j = a.Count - 1;
        while(i

And the demo/test code:

        var src = "1234".ToCharArray();
        do
        {
            Console.WriteLine(src);
        } 
        while (NextPermutation(src));