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HI
🎉 ¡Felicidades! 🎉
¡Has resuelto la tarea brillantemente! Era un reto difícil, pero encontraste la solución correcta. ¡Estás un paso más cerca de dominar la programación! Sigue así, cada etapa superada te hace más fuerte.
Lección 2. Conditions
Dificultad:
Tarea«El hechizo del mago»
💻 Python
El joven mago Alex encontró una receta para un hechizo de levitación en un antiguo grimorio. El libro dice que se necesitan tres componentes clave para tener éxito: una lágrima de grifo, raíz de mandrágora y polvo lunar. El viejo mago-mentor le dijo a Alex que el hechizo funcionaría solo si al menos dos de los tres ingredientes se añaden correctamente.
Escribe el programa para verificar si su hechizo funcionará. El programa debe solicitar el estado de cada uno de los tres ingredientes. El usuario introduce 1 , si el ingrediente se añade correctamente (verdadero), y 0 , si es incorrecto (falso).
Dependiendo de los datos ingresados, el programa debe mostrar uno de dos resultados: "¡El hechizo funcionó!" o "El hechizo no funcionó.".
Formato de entrada
el estado del primer ingrediente (entero: 1 o 0)
el estado del segundo ingrediente (entero: 1 o 0)
el estado del tercer ingrediente (entero: 1 o 0)
Formato de salida
El resultado del hechizo (línea)
Ejemplo
Entrada
1
1
0
Salida
The spell worked!
Pista
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
Prueba 1
Prueba 2
Prueba 3
Prueba 4
Prueba 5
Prueba 6
Prueba 7
Prueba 8
Prueba 9
Prueba 10
Solución del desarrollador
# Запрашиваем у пользователя состояние для каждого из трёх ингредиентов.
# Используем int() для преобразования введённой строки в целое число (0 или 1).
ingredient1 = int(input())
ingredient2 = int(input())
ingredient3 = int(input())
# Складываем значения всех трёх переменных.
# Если два или три ингредиента верны (1), сумма будет 2 или 3.
# Если верных ингредиентов меньше двух, сумма будет 0 или 1.
correct_ingredients_count = ingredient1 + ingredient2 + ingredient3
# Проверяем условие: если количество верных ингредиентов больше или равно двум.
if correct_ingredients_count >= 2:
# Если условие истинно, выводим сообщение об успехе.
print("Заклинание сработало!")
else:
# Если условие ложно, выводим сообщение о неудаче.
print("Заклинание не сработало.")
