n = int(input("请输入n的值(n≥1)："))
if n < 1:
    print("输入错误,n需≥1")
else:
    sum_series = 0.0 # 用浮点数存储结果
    for i in range(1, n + 1):
        sum_series += 1 / i
    print(f"数列前{n}项和：{sum_series:.6f}") # 保留6位小数

n = int(input("请输入一个正整数："))
if n <= 0:
    print("输入错误,请输入正整数")
else: # 计算阶乘
    factorial = 1
    for i in range(1, n + 1):
        factorial *= i
    print(f"{n}的阶乘是：{factorial}")

# 思路：每行 = 空格 + 递增字母 + 递减字母(去掉最后一个)
n = int(input("请输入金字塔高度："))
for i in range(n):
    # 1. 打印左侧空格
    print(" " * (n - 1 - i), end="")
    # 2. 打印递增字母(A到当前字母)
    for j in range(i + 1):
        print(chr(65 + j), end="")
    # 3. 打印递减字母(当前字母前一个到A)
    for j in range(i - 1, -1, -1):
        print(chr(65 + j), end="")
    # 4. 换行
    print()

# 思路：每行 = 空格 + * + 空格
# 行数5,第i行(从0开始)：空格数=4-i,*数=2i+1
height = 5
for i in range(height): # 计算空格和*的数量
    space = " " * (height - 1 - i)
    star = "*" * (2 * i + 1)
    print(space + star)

# 思路：菱形=上三角+下三角
height = 4
# 打印上三角(含中间行)
for i in range(height):
    space = " " * (height - 1 - i)
    star = "*" * (2 * i + 1)
    print(space + star)
# 打印下三角(去掉最后一行)
for i in range(height-2, -1, -1):
    space = " " * (height - 1 - i)
    star = "*" * (2 * i + 1)
    print(space + star)

primes = []
for num in range(2, 101):
    is_prime = True
    for i in range(2, num):            #质数判断
        if num % i == 0:
            is_prime = False
            break
    if is_prime:
        primes.append(str(num))
for i in range(0,len(primes),5):    #每行打印5个
    print(" ".join(primes[i:i+5]))

# 定义要统计的区间
start = 10
end = 30
# 存储区间内的质数
prime_list = []
# 遍历区间内的每个数,判断是否为质数
for num in range(start, end + 1):
    # 基础质数判断逻辑
    if num <= 1:
        continue
    if num == 2:
        prime_list.append(num)
        continue
    if num % 2 == 0:
        continue
    # 判断奇数是否为质数(只需检查到√num)
    is_prime = True
    for i in range(3,int(num ** 0.5) + 1,2):
        if num % i == 0:
            is_prime = False
            break
    if is_prime:
        prime_list.append(num)
# 打印结果
# 把质数列表转成字符串,用空格分隔
prime_str = " ".join(map(str, prime_list))
# 输出质数列表和个数
print(f"{start}到{end}之间的质数有：{prime_str}")
print(f"质数的总个数：{len(prime_list)}")

def fibonacci(n):
    # 处理边界情况：n为0或负数时返回空列表
    if n <= 0:
        return []
    # n=1时,仅返回第一个数0
    elif n == 1:
        return [0]
    # n=2时,返回前两个数[0, 1]
    elif n == 2:
        return [0, 1]
    # n>2时,循环生成后续项
    else:
        fib_list = [0, 1]
        # 从第3项（索引2）开始,直到第n项（索引n-1）
        for i in range(2, n):
            # 第i项 = 第i-1项 + 第i-2项
            next_num = fib_list[i-1] + fib_list[i-2]
            fib_list.append(next_num)
        return fib_list
print(fibonacci(6))

def generate_geometric_sequence(start, ratio, n):
    """生成等比数列,支持浮点数和边界处理"""
    if n == 0:
        return []
    sequence = [start] # 第一项为起始值
    # 从第二项开始计算
    for i in range(1, n):
        current = start * (ratio ** i)
        sequence.append(current)
    return sequence
print(generate_geometric_sequence(2, 0.5, 4)) # [2, 1.0, 0.5, 0.25]

def get_leap_years(start_year, end_year):
    leap_years = []
    # 遍历区间内的每一个年份
    for year in range(start_year, end_year + 1):
        # 闰年判断规则：
        # 1. 能被400整除  或  2. 能被4整除但不能被100整除
        if (year % 400 == 0) or (year % 4 == 0 and year % 100 != 0):
            leap_years.append(year)
    return leap_years
print(get_leap_years(2000, 2010))  # 输出：[2000, 2004, 2008]

def extract_digits(num):
    """提取非负整数的每一位数字(高位到低位)"""
    # 处理负数和非整数情况
    if not isinstance(num, int) or num < 0:
        return [] # 处理0的特殊情况
    if num == 0:
        return [0]
    # 存储数位的列表
    digits = []
    # 先将数字转为字符串,遍历每个字符再转回整数
    for char in str(num):
        digits.append(int(char))
    return digits
print(extract_digits(1234)) # [1, 2, 3, 4]
print(extract_digits(0)) # [0]
print(extract_digits(-567)) # []

def compute_sum(a, n):
    total = 0
    current = 0
    for i in range(n):
        current = current * 10 + a
        total += current
    return total
print(compute_sum(2,5))

def filter_dict_by_value(d, threshold):
    """筛选字典中值大于阈值的键值对,返回新字典"""
    filtered_dict = {} # 遍历原字典的键值对
    for key, value in d.items():
        if value > threshold:
            filtered_dict[key] = value
    return filtered_dict
scores = {"math": 85, "chinese": 92, "english": 78}
print(filter_dict_by_value(scores,80))        #{'math':85,'chinese':92}
print(filter_dict_by_value({"a": 5, "b": 3, "c": 7}, 7))     # {}

def update_nested_dict():
    # 初始化嵌套字典
    students = {
        "001": {"name": "张三", "scores": {"math": 88, "english": 90}},
        "002": {"name": "李四", "scores": {"math": 75, "english": 82}}
    }
    # 1. 获取001的数学成绩
    math_score_001 = students["001"]["scores"]["math"]
    print("001的数学成绩：", math_score_001)  # 输出88
    # 2. 修改002的英语成绩为85
    students["002"]["scores"]["english"] = 85
    # 3. 为001新增语文成绩
    students["001"]["scores"]["chinese"] = 95
    # 4. 返回修改后的字典
    return students
result = update_nested_dict()
print(result)
    # 输出：
    # {'001': {'name': '张三', 'scores': {'math': 88, 'english': 90, 'chinese': 95}},
    #  '002': {'name': '李四', 'scores': {'math': 75, 'english': 85}}}

def calculate_average(*args):
    """计算任意个数数字的平均值,过滤非数字参数"""
    # 筛选出数字类型的参数
    numbers = []
    for arg in args:
        if isinstance(arg, (int, float)):
            numbers.append(arg)
    # 处理空列表
    if not numbers:
        return 0
    # 计算平均值
    return sum(numbers) / len(numbers)
print(calculate_average(1, 2, 3, 4)) # 2.5
print(calculate_average(10, "abc", 20, 30)) # 20.0
print(calculate_average()) # 0

def calculate_bmi(weight, height, unit="m"):
    """计算BMI,支持米/厘米单位,默认米"""
    # 基础校验
    if not (isinstance(weight, (int, float)) and isinstance(height, (int, float))):
        return None
    if weight <= 0 or height <= 0:
        return None
    # 单位转换：厘米转米
    if unit == "cm":
        height = height / 100
    elif unit != "m":
        return None # 无效单位
    # 计算BMI并保留2位小数
    bmi = weight / (height ** 2)
    return round(bmi, 2)
print(calculate_bmi(60, 1.75)) # 19.59
print(calculate_bmi(60, 175, "cm")) # 19.59
print(calculate_bmi(60, 0)) # None