I looked long and hard for a suitable sample of the Enumerable::SelectMany static method in C++, but could not find one. After some tweaking and converting from C#, I now have a suitable example. The tricky part when converting this FROM C# is that C# does not require the extra Select inside the SelectMany, but C++ requires it.
This code takes a two dimensional array of strings and collapses it into a distinct list of strings.
Part of the magic was figuring out to cast the array as an IEnumerable^>^, which was apparent after first creating this in C#.
I had to change this to a graphic as my code importer was stripping off things in angle brackets.