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你出色地完成了任务！这是一个不小的挑战，但你找到了正确答案。你离编程大师又近了一步！继续保持，每一步都让你更强大。
课程 2. Conditions
难度：
任务«虚拟农场»
💻 Python
农夫费奥多尔决定清点他的农场，并将所有动物安置在三个宽敞的新畜栏中。每个畜栏的容量——正好是10只动物。
编写一个程序，帮助费奥多尔快速判断是否有足够的空间容纳所有动物。程序应询问农夫奶牛、绵羊和鸡的数量，然后告知它们是否能被安置在三个畜栏中。如果有空间，程序还应计算会剩余多少个空位。如果空间不足，则需要指出有多少只动物没有位置。
输入格式
三个整数，每个整数在相应的提示后从新的一行输入。
第一个数字：奶牛的数量（整数）。
第二个数字：绵羊的数量（整数）。
第三个数字：鸡的数量（整数）。
输出格式
两行文本。
第一行：关于是否能够安置动物的答案（行）。
第二行：剩余空位或缺少位置的数量（行）。
示例
输入
5
8
10
输出
是的，所有动物都可以被放置。
将有7个空位。
提示
Nested conditions
You can nest some conditional statements (if) into others to create more complex and multi-level checks. This is useful when the next action depends on several consecutive conditions.
The key point here is the correct indentation (usually 4 spaces), which shows Python which block of code belongs to which condition.
Example:
x = 10
if x > 5:
print("First check passed: x is greater than 5.")
if x < 20:
print("Second check passed: x is also less than 20.")
else:
print("Second check failed: x is at least 20.")
else:
print("First check failed: x is less than or equal to 5.")
A useful tip: Try not to create too many nesting levels (3 or more). Deeply embedded code becomes difficult to read and understand. Often, complex nesting can be simplified by using logical operators.
Logical operators
Logical operators in Python are used to combine two or more conditions. They allow you to build complex logic without putting conditions into each other. The main logical operators are and, or and not.
| The | Name | Description |
|---|---|---|
or |
logical "OR" | Returns True if at least one condition is true. |
and |
logical "And" | Returns True only if both conditions are true. |
not |
logical "NOT" (negation) | Inverts the result: True becomes False and vice versa. |
Examples:
a = 5
b = 7
# and: both conditions must be true
s1 = a > 3 and b < 10 # True and True -> True
# or: at least one condition must be true
s2 = a != 5 or b >= 7 # False or True -> True
# not: inverts the result
s3 = not (a < b) # not (True) -> False
When using and, the result will be true only if both operands are true. When using or, it is sufficient for at least one of the operands to be true. The not operator turns a lie into the truth and vice versa.
Analysis of a complex example:
a, b, c = 7, 10, 11
# Original expression:
print(not(a > 7 and b <= 10) or c != 17)
# Let's take it step by step:
# 1. a > 7 -> 7 > 7 -> False
# 2. b <= 10 -> 10 <= 10 -> True
# 3. (False and True) -> False
# 4. not(False) -> True
# 5. c != 17 -> 11 != 17 -> True
# 6. True or True -> True
# Result: True
A useful tip: To improve readability and avoid errors in complex expressions, always use parentheses () to explicitly specify the order of calculations, even if you remember the precedence of operators (not has the highest priority, then and, then or).
The ternary operator
The ternary operator is a compact way to write a simple if-else condition that returns a value. It allows you to assign a variable a value depending on the condition, and all this in one line.
Syntax: [value if true] if [condition] else [value if false]
Examples:
x = 10
# If x > 5, result will be 100, otherwise 200
result = 100 if x > 5 else 200
print(result) # Will output: 100
y = 20
# Assign the larger of the two values to the variable z
z = x if x > y else y
print(z) # Outputs: 20
# Assign a text value
result_text = "positive" if x > 0 else "non-positive"
print(result_text) # Outputs: positive
A useful tip: The ternary operator is great for simple assignments. However, if the logic becomes more complicated or if, depending on the condition, you need to perform different actions (rather than just return a value), it is better to use a full-fledged if-else construct to preserve the readability of the code.
One-line conditions
If the condition body (if, elif, or else) consists of only one instruction, Python allows you to write it in the same line after the colon.
Example:
x = 10
if x > 5: print("x is greater than 5")
Important style note: Although this notation is syntactically correct, it is often not recommended by the Python Code Style Guide (PEP 8). Placing instructions on a separate line with indentation improves readability and is a generally accepted standard. Use a one-line entry with care, mostly for very simple and obvious actions.
main.py
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测试 10
开发者解答
# Запрашиваем у пользователя количество животных каждого вида.
# Функция int() преобразует введенный текст в целое число.
cows = int(input())
sheep = int(input())
chickens = int(input())
# Рассчитываем общее количество животных путем сложения.
total_animals = cows + sheep + chickens
# Определяем общую вместимость всех загонов (3 загона * 10 мест).
total_capacity = 30
# Используем условие if/else для проверки, поместятся ли все животные.
if total_animals <= total_capacity:
# Этот блок кода выполняется, если общее количество животных меньше или равно вместимости.
free_space = total_capacity - total_animals # Вычисляем количество свободных мест.
print("Да, всех животных можно разместить.")
print("Останется свободных мест:", free_space)
else:
# Этот блок кода выполняется, если животных больше, чем мест.
shortage = total_animals - total_capacity # Вычисляем, скольких мест не хватает.
print("Нет, всех животных разместить нельзя.")
print("Не хватает мест:", shortage)
