递归小列

Posted 2020-10-30 zqxqx

1 用递归求5！

方法一

#!/urs/bin/env python
# -*- coding:utf-8 -*-


def factorial(num):
    """
    求5的阶乘
    :param num: 
    :return: 
    """
    if num < 5:
        return num*factorial(num+1)
    else:
        return num
if __name__ == "__main__":
    evaluation = factorial(1)
    print(evaluation)

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 方法二

#!/urs/bin/env python
# -*- coding:utf-8 -*-
import functools
result = (lambda k: functools.reduce(int.__mul__, range(1, k+1), 1))(5)
print(result)

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2  [0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, **, **, **, **, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99],查找一个数字,如果找到则打印该数字,如果找不到,则输出“not found!”

方法一

#!/urs/bin/evn python
# -*- coding:utf-8 -*-

# c = [] 测试
number = [0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99]


def name(num):
    for i in number:
        if num == i:
            return num
    else:
        return "not found!"
if __name__ == "__main__":
    while True:
        number1 = int(input("请输入要判断的数在不在："))
        results = name(number1)
        print("查询结果：%s" % results)

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方法二

#!/urs/bin/evn python
# -*- coding:utf-8 -*-
number_list = [0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99]


def search(num_list, num):
    """
    查找num的值是否在num_list中，二分法。
    :param num_list:
    :param num:
    :return:
    """
    lower = 0
    upper = len(num_list)-1
    if lower == upper:
        if num == num_list[upper]:
            return True
        else:
            return False
    else:
        middle = upper//2
        if num < num_list[middle]:
            num_list = num_list[:middle]
            return search(num_list, num)
        if num > num_list[middle]:
            num_list = num_list[middle+1:]
            return search(num_list, num)
        else:
            return True


def main():
    """
    主程序
    :return: 
    """
    while True:
        num = input(">>:").strip()
        try:
            num = int(num)
        except:
            raise TypeError("请输入数字")
        if search(number_list, num):
            print("%d存在列表中" % num)
        else:
            print("该值不存在")
if __name__ == "__main__":
    main()

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