Understanding - Advanced, exercise 33

Text

The variable my_mat_string contains the string of all the ten numbers of a matriculation number (e.g. "0235145398"), and my_full_name is a string of a full name all in lowercase with no spaces (e.g. "johndoe"). What is the value returned by calling the function rsel as shown as follows: rsel(my_full_name, my_mat_string).

def rsel(full_name, mat_string):
    uniq = []
    for c in full_name:
        if c not in uniq:
            uniq.append(c)
    
    r = []
    i = len(mat_string) // 2
    if i > 0:
        n = int(mat_string[i])
        if n < len(uniq):
            r.append(uniq[n])
            new_full_name = full_name[:n] + full_name[n+1:]
            new_mat_string = mat_string[:n] + mat_string[n+1:]
            r.extend(rsel(new_full_name, new_mat_string))
    
    return r

Hints

The function rsel is a recursive function that, at every call, reduce both the input parameters of one character.

Additional material

The runnable Python file is available online. You can run it executing the command python exercise_33.py in a shell, and then following the instructions on screen to specify the intended input.