Example of O(n!)?

Question

What is an example (in code) of a O(n!) function? It should take appropriate number of operations to run in reference to n; that is, I\'m asking a

Answer 1

In C#

Wouldn't this be O(N!) in space complexity? because, string in C# is immutable.

string reverseString(string orgString) {
    string reversedString = String.Empty;

    for (int i = 0; i < orgString.Length; i++) {
        reversedString += orgString[i];
    }

    return reversedString;
}