Exercise 06-22:
Write a program that compares two lists. Consider the first list as the initial version and the second as the version after changes. Using operations with sets, your program should print the list of modifications between these two versions, listing:
- The elements that haven’t changed
- The new elements
- The elements that were removed
Answer:
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# Python From Scratch
# Author: Nilo Ney Coutinho Menezes
# Editora Novatec (c) 2010-2025 - LogiKraft 2025
# Site: https://pythonfromscratch.com
# ISBN: 978-85-7522-949-1 (Paperback), 978-85-7522-950-7 (hardcover), 978-85-7522-951-4 (ebook)
#
# File: chapter 06/exercise-06-22.py.py
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BEFORE = [1, 2, 5, 6, 9]
AFTER = [1, 2, 8, 10]
before_set = set(BEFORE)
after_set = set(AFTER)
# Sets support the & operator to perform intersection, that is,
# A & B results in the set of elements present in both A and B
print("Before:", BEFORE)
print("After:", AFTER)
print("Elements that did not change: ", before_set & after_set)
print("New elements:", after_set - before_set)
print("Elements that were removed:", before_set - after_set)