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"""
python中的递归函数, time模块中的sleep(单位是秒s)
1- 用现有的while循环来实现
2- 递归实现，必须有一个停止的条件来调用自己
"""
import time
# def a_func(duration):
# while duration > 0:
# time.sleep(1)
# print("重新发送(%ss)" % (duration -1))
# duration -= 1
#
# a_func(3)
# def b_func(duration):
# if duration > 0:
# time.sleep(1)
# print("重新发送(%ss)" % (duration -1))
# duration -= 1
#
# b_func(duration)
# b_func(3)
"""
n! = {
if -> n * (n - 1)! if( n>=0)
else -> 1 if( n=0)
}
1- f(3) -> 3*f(2)
2- f(2) -> 2*f(1)
3- f(1) -> 1*f(0)
4- f(0) -> return 1
"""
def c_func(num):
if num > 1:
return num * c_func(num - 1)
else:
return 1
print(c_func(3))
"""
递归的核心就是将表达式分部分，重复的部分和截至的部分
递归求fib序列: 1 1 2 3 5 8
fib(n) = {
n = fib(n-2) + fib(n-1) if n>2
n = 1 else (n=1 or n=2)
}
"""
def d_func(num):
if num > 2:
return d_func(num-2) + d_func(num-1)
else:
return 1
print(d_func(6))
"""
youtube上跳楼梯的递归算法，求多少种可能性,实质答案就是fib序列
主要关键是第一步跳1还是2，或者说迈大步还是迈小步
"""
def e_func(floor):
if floor == 1 or floor == 0:
return 1
else:
return e_func(floor-1) + e_func(floor-2)
print(e_func(4))
"""
lambda关键字表示这是一个匿名函数，通过小括号来执行()
"""
# 无参数无返回值
def f_func():
print("Hello World 1")
f_func()
a_lambda = lambda: {
print("Hello World 2")
}
a_lambda()
(lambda: {print("Hello World 3")})()
# 无参数有返回值, lambda冒号后面不用写return
def e_func():
return "Hello World 4"
print(e_func())
print((lambda: "Hello World 5")())
# 有参数，无返回值,参数写在lambda后面，冒号前面
def f_func(name):
print(("Hello World 6 --> %s" % name))
f_func("张三")
(lambda name: {print(("Hello World 7 --> %s" % name))})("张三")
# 有参数，有返回值
def g_func(name):
return "Hello World 8 --> %s" % name
print(g_func("李四"))
print((lambda name: {"Hello World 9 --> %s" % name})("李四"))
"""
匿名函数lambda作为函数参数
函数内a,b进行特定操作后，最后交给callback进行回掉
"""
def h_func(a,b,callback):
print("result = %d" % callback(a,b))
# lambda a,b: a + b
h_func(3,5, lambda a,b: a + b)