1.高阶函数
1.1高阶函数定义
变量可以指向函数，函数的参数能接受变量，那么一个函数就可以接收另一个函数作为参数，这种函数就称为高阶函数。
只要满足以下任意一个条件，即是高阶函数
1.接收一个或多个函数作为输入
2.return返回另外一个函数
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
def add(x, y, func):
return func(x) + func(y)
res = add(3, -6, abs)
print(res)
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
9
Process finished with exit code 0
2.递归
2.1递归定义
在函数内部，可以调用其它函数。如果一个函数在内部调用自身，这个函数就是递归函数。
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
def calc(n):
print(n)
if int(n/2) == 0:
return n
return calc(int(n/2))
calc(4)
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
4
2
1
Process finished with exit code 0
2.2递归的执行过程
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author: vita
def calc(n):
print(n)
if int(n/2) > 0:
calc(int(n/2))
print(n)
calc(4)
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
4
2
1
1
2
4
Process finished with exit code 0
```
## 2.3递归特性
>1.必须有一个明确的结束条件
>2.每次进入更深一层递归时，问题规模相比上次递归都应有所减少
>3.递归效率不高，递归层次过多会导致栈溢出（在计算机中，函数调用时通过栈(stack)这种数据结构实现的，每当进入一个函数调用，栈就会加一层栈帧，每当函数返回，栈就会减一层栈帧。由于栈的大小不是无限的，所以递归调用的次数过多，会导致栈溢出）
## 2.4二分法查找#!/usr/bin/env python-- coding:utf-8 --
Author: vita
data = [1, 3, 5, 7, 8, 10, 30, 34, 35]
def binary_search(source_data, search_data):
print(source_data)
if len(source_data) > 1:
mid_data_index = int(len(source_data)/2)
if source_data[mid_data_index] == search_data:
print("excellent,you have found it!")
elif source_data[mid_data_index] > search_data:
source_data = source_data[0:mid_data_index]
binary_search(source_data, search_data)
elif source_data[mid_data_index] < search_data:
source_data = source_data[mid_data_index + 1:]
binary_search(source_data, search_data)
else:
if len(source_data) == 0:
print("source data is null now!")
else:
if source_data[0] == search_data:
print("you have found it!")
else:
print("there is not this number!")
binary_search(data, 30)
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
[1, 3, 5, 7, 8, 10, 30, 34, 35]
[10, 30, 34, 35]
[10, 30]
excellent,you have found it!
Process finished with exit code 0
"找4"
binary_search(data, 4)
E:\PythonProject\python-test\venvP3\Scripts\python.exe E:/PythonProject/python-test/BasicGrammer/test.py
[1, 3, 5, 7, 8, 10, 30, 34, 35]
[1, 3, 5, 7]
[1, 3]
[]
source data is null now!
Process finished with exit code 0
```