理论与实践

数据输入输出

任务

条件语句

任务

for循环

任务

字符串

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while循环

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列表

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二维数组

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字典

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集合

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函数与递归

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课程 2. Conditions

难度：

任务«温室内的气候»

💻 Python

你——阿格隆，负责现代化的自动温室。你的任务——为控制气候的微控制器编写程序。系统应分析来自温度和湿度传感器的数据，并给出以下三种命令之一：“开启加热”、“给植物浇水”或报告“一切正常”。

规则如下：

寒冷检查具有最高优先级。如果温度降至 15 度以下，无论湿度如何，必须立即开启加热。
如果温室内不冷，则需要检查是否需要浇水。当温度 高于 25 度或湿度 低于 50% 时，需要浇水。
如果以上条件均不满足，则温室内气候处于最佳状态。

用户输入两个整数（温度和湿度），程序在屏幕上输出相应的命令。

输入格式

两个整数，每个占一行。第一个——温度（整数），第二个——湿度（整数）。

输出格式

一行包含推荐内容（line）。

示例

输入

28
60

输出

给植物浇水

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

测试 1

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测试 5

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测试 7

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测试 9

测试 10

开发者解答

# Считываем показания датчиков с двух разных строк
temperature = int(input()) # Вводим температуру и преобразуем в целое число
humidity = int(input())    # Вводим влажность и преобразуем в целое число

# Проверяем условия по заданному приоритету
if temperature < 15:
    # Сначала проверяем на холод, так как это самый критичный параметр
    print("Включить отопление")
elif temperature > 25 or humidity < 50:
    # Если не холодно, проверяем, не жарко ли или не сухо ли
    print("Поливать растения")
else:
    # Если все предыдущие проверки не сработали, значит, условия оптимальны
    print("Всё в порядке")