Understanding - Advanced, exercise 23

Text

The variable my_mat_string contains the string of a 10-digit matriculation number (e.g. "0000123456"). Study the execution of the following function when it is called as follows: f(my_mat_string).

from collections import deque

def f(m_string):
    c = 0
    s = deque(m_string)
    while s:
        cur = int(s.pop())
        if cur % 2:
            c = c + 1
    
    m_len = len(m_string)
    m_col = list()
    while c < m_len - c:
        m_col.append(m_string[c])
        c = c + 1
    
    for i, d in enumerate(reversed(m_string)):
        if d not in m_col:
            if i < len(m_col):
                m_col.insert(i, d)
            else:
                m_col.append(d)
    
    return m_col

Hints

The function f is organised in three blocks. The first block calculates the values of a variable c looking at the content of the input string. The second block modifies again the value of c according to other criteria and creates a list of strings, that is used and modified in the third block to create the final result.

Additional material

The runnable Python file is available online. You can run it executing the command python exercise_23.py in a shell, and then following the instructions on screen to specify the intended input.