Understanding - Advanced, exercise 6

Text

The variable my_gn contains the string of a given name in lowercase (e.g. "john"), while the variable my_fn contains the string of a family name lowercase (e.g. "doe"). Study the execution of the following functions when they are called as follows: r(my_gn, my_fn).

def r(gn, fn):
    g = ""
    f = None
    fl = list()
    for c in fn:
        fl.append(c)

    if len(fn) <= 1:
        return fn + gn
    else:
        for c in reversed(gn):
            if c >= fn[0]:
                g += c
            else:
                f = fn[1]
                g += f

        if f:
            fl.remove(f)
        else:
            fl.remove(fl[0])

        return r(g, "".join(fl))

Hints

The recursive function r checks the composition of the family name (variable fn) to decide if it should return a result by combining the two input strings, or if it should modify them somehow and continue the processing by a recursive call.

Additional material

The runnable Python file is available online. You can run it executing the command python exercise_6.py in a shell, and then following the instructions on screen to specify the intended input.