"""
Урок 37. Практикум 9 — весь код примеров одним файлом.

Источник: subjects/python-fundamentals/course/lessons/37-practice-9/examples.html
Файл собран автоматически (tools/build_lesson_examples.py): правьте страницу урока.
Запуск: python lesson-37.py
"""



# ====================================================================
# Пример 1. Задание 1 — числа, кратные 3 или 5
# ====================================================================
numbers = [16, 18, 1, 6, 3, 2, 6, 2, 14, 3, 20, 15, 19, 4, 18, 15, 15, 4, 20, 18]
result = {number for number in numbers if number % 3 == 0 or number % 5 == 0}
print(result)             # {3, 6, 15, 18, 20}
print(len(numbers), len(result))   # 20 5


# ====================================================================
# Пример 2. Задание 2 — общие ключи двух словарей
# ====================================================================
dict1 = {"a": 1, "b": 2, "c": 3}
dict2 = {"b": 5, "d": 7, "a": 8}
common_keys = set(dict1) & set(dict2)
print(sorted(common_keys))   # ['a', 'b']
if common_keys:
    print(", ".join(sorted(common_keys)))   # a, b
else:
    print("-")

dict3 = {"x": 1}
common_none = set(dict1) & set(dict3)
print(common_none if common_none else "-")   # -


# ====================================================================
# Пример 3. Задание 3 — список строк в словарь длин
# ====================================================================
words = ["apple", "banana", "cherry", "date"]
lengths = {word: len(word) for word in words}
print(lengths)   # {'apple': 5, 'banana': 6, 'cherry': 6, 'date': 4}


# ====================================================================
# Пример 4. Задание 4 — проверка подмножества словаря
# ====================================================================
dict_a = {"a": 1, "b": 2}
dict_b = {"a": 1, "b": 2, "c": 3}
is_subset = all(item in dict_b.items() for item in dict_a.items())
print(is_subset)   # True

dict_c = {"a": 1, "b": 99}
is_subset2 = all(item in dict_b.items() for item in dict_c.items())
print(is_subset2)   # False — ключи те же, а значение "b" другое


# ====================================================================
# Пример 5. Задание 5 — удаление пустых значений
# ====================================================================
data = {"a": None, "b": 2, "c": "", "d": [], "e": [1, 2], "f": 0}
cleaned = {key: value for key, value in data.items() if value}
print(cleaned)   # {'b': 2, 'e': [1, 2]}


# ====================================================================
# Пример 6. Задание 6 — потерянные страницы книги
# ====================================================================
book = {1: "Начало истории", 2: None, 3: "Глава 1", 4: None, 5: "Глава 2"}
fixed_book = {
    page: (text if text is not None else "Страница потеряна")
    for page, text in book.items()
}
print(fixed_book)
# {1: 'Начало истории', 2: 'Страница потеряна', 3: 'Глава 1', 4: 'Страница потеряна', 5: 'Глава 2'}


# ====================================================================
# Пример 7. Задание 7 — вложенный словарь оценок
# ====================================================================
grades = {
    "anna": [5, 4, 3, 5],
    "bennet": [3, 2, 4],
    "john": [5, 5, 5],
}

report = {}
for student, marks in grades.items():
    report[student] = {
        "оценки": marks,
        "средний балл": sum(marks) / len(marks),
    }

print(report)
# {'anna': {'оценки': [5, 4, 3, 5], 'средний балл': 4.25},
#  'bennet': {'оценки': [3, 2, 4], 'средний балл': 3.0},
#  'john': {'оценки': [5, 5, 5], 'средний балл': 5.0}}


# ====================================================================
# Пример 8. Задание 8 — рецепты по набору ингредиентов
# ====================================================================
recipes = {
    ("flour", "egg", "milk"): "Pancakes",
    ("milk", "flour", "egg"): "Waffles",
    ("sugar", "butter"): "Icing",
}

grouped_recipes = {}
for ingredients, recipe in recipes.items():
    grouped_recipes.setdefault(frozenset(ingredients), []).append(recipe)

print(grouped_recipes[frozenset(["egg", "milk", "flour"])])
# ['Pancakes', 'Waffles']

available = {"egg", "milk", "flour", "sugar"}
for ingredients_needed, recipe_names in grouped_recipes.items():
    if ingredients_needed.issubset(available):
        print(f"Можно приготовить: {recipe_names} из {sorted(ingredients_needed)}")
# Можно приготовить: ['Pancakes', 'Waffles'] из ['egg', 'flour', 'milk']


# ====================================================================
# Пример 9. Задание 9 — студенты с одинаковым набором предметов
# ====================================================================
students = {
    "Alice": ["Math", "Physics"],
    "Bob": ["Math", "Physics"],
    "Charlie": ["Chemistry", "Biology"],
    "David": ["Math", "Physics"],
    "Eve": ["Chemistry", "Biology"],
}

groups = {}
for student, subjects in students.items():
    groups.setdefault(frozenset(subjects), []).append(student)

for subjects, names in groups.items():
    print(f"Группа с предметами: {', '.join(sorted(subjects))}: {names}")
# Группа с предметами: Math, Physics: ['Alice', 'Bob', 'David']
# Группа с предметами: Biology, Chemistry: ['Charlie', 'Eve']


# ====================================================================
# Пример 10. Задание 10 — перевод слова с предложением добавить новое
# ====================================================================
english_words = {"cat": "кот", "dog": "собака", "bird": "птица"}

def translate(word, dictionary):
    if word in dictionary:
        return dictionary[word]
    return f"'{word}' нет в словаре — добавьте перевод"


print(translate("cat", english_words))    # кот
print(translate("fish", english_words))   # 'fish' нет в словаре — добавьте перевод

english_words["fish"] = "рыба"
print(translate("fish", english_words))   # рыба


# ====================================================================
# Пример 11. Почему frozenset, а не set, годится в ключ словаря
# ====================================================================
try:
    bad = {{"egg", "milk"}: "pancakes"}
except TypeError as error:
    print(f"TypeError: {error}")
# TypeError: unhashable type: 'set'

good = {frozenset(["egg", "milk"]): "pancakes"}
print(good)   # {frozenset({'egg', 'milk'}): 'pancakes'}
# — порядок элементов внутри frozenset не гарантирован, у вас может быть другим
print(frozenset(["egg", "milk"]) == frozenset(["milk", "egg"]))   # True