# 基本输入
name = input("Enter your name: ")
print(f"Hello, {name}!")

# 数字输入（需要类型转换）
age_str = input("Enter your age: ")
age = int(age_str)
print(f"Next year you will be {age + 1}")

# 多行输入提示
prompt = "Please enter your favorite color: "
prompt += "(or 'quit' to exit) "
color = input(prompt)

# 基本while循环
count = 0
while count < 5:
    print(f"Count: {count}")
    count += 1

# 使用标志
active = True
while active:
    message = input("Enter something (or 'quit' to exit): ")
    if message == 'quit':
        active = False
    else:
        print(f"You said: {message}")

# break和continue
while True:
    item = input("Enter item (or 'done'): ")
    if item == 'done':
        break
    if item == '':
        continue
    print(f"Added: {item}")

# 从未确认移到已确认
unconfirmed = ["alice", "bob", "charlie"]
confirmed = []

while unconfirmed:
    current = unconfirmed.pop()
    print(f"Confirming: {current}")
    confirmed.append(current)

print("\nConfirmed users:")
for user in confirmed:
    print(user.title())

# 删除特定元素
pets = ["dog", "cat", "dog", "goldfish", "cat", "rabbit"]
while "cat" in pets:
    pets.remove("cat")
print(pets)

# 验证数字输入
while True:
    try:
        number = int(input("Enter a number between 1-10: "))
        if 1 <= number <= 10:
            break
        print("Number must be between 1 and 10")
    except ValueError:
        print("Please enter a valid number")

print(f"You entered: {number}")

# 验证用户名
def get_valid_username():
    while True:
        username = input("Enter username (3-20 chars): ")
        if 3 <= len(username) <= 20:
            return username
        print("Username must be 3-20 characters")

name = get_valid_username()
print(f"Username: {name}")

import random

def guess_number():
    secret = random.randint(1, 100)
    attempts = 0
    max_attempts = 7
    
    print("=== Guess the Number ===")
    print("I'm thinking of a number between 1 and 100.")
    
    while attempts < max_attempts:
        try:
            guess = int(input(f"Attempt {attempts + 1}/{max_attempts}: "))
        except ValueError:
            print("Please enter a valid number")
            continue
        
        attempts += 1
        
        if guess == secret:
            print(f"Congratulations! You guessed it in {attempts} attempts!")
            return True
        elif guess < secret:
            print("Too low!")
        else:
            print("Too high!")
    
    print(f"Game over! The number was {secret}")
    return False

# 运行游戏
while True:
    guess_number()
    play_again = input("Play again? (y/n): ")
    if play_again.lower() != 'y':
        break