Python递归函数

所谓递归就是在函数内部调用自己的函数被称之为递归，一般递归函数都有终止条件，采用的是后入先出的压栈数据结构。

阶乘函数 n!

def factorial(n):

    if n == 1:
        return 1

    return n * factorial(n - 1)

斐波那契数列 1, 1, 2, 3, 5, 8...

def fibonacci(n):

    if n < 2:
        return n

    return fibonacci(n - 2) + fibonacci(n - 1)

从递归函数谈

os.walk()
os.listdir()
os.mkdir()
os.makedirs()
os.rmdir()
os.removedirs()
copy.copy()
copy.deepcopy()

深浅拷贝

从递归函数谈reduce

os.listdir递归查找文件

children递归查找filecache

斐波拉契数列 1 1 2 3 5 8

def fibonacci(num):
    if isinstance(num, int):
        if num <= 0:
            return 0
        elif num == 1:
            return 1
        else:
            return fibonacci(num - 1) + fibonacci(num - 2)
    else:
        raise ValueError("The input number error!")

def factorial(number):

    if not isinstance(number, int) or number <= 0:
        return

    result = 1

    for n in range(1, number + 1)
        result *= n

    return result

factorial(100)

def fact(number):
    if number == 1:
        return number
    return number * fact(number - 1)

# os.walk()
import os
from pprint import pprint

def walkFolders(folderPath):
    subFileList = []
    for subFileName in os.listdir(folderPath):
        subPath = os.path.join(folderPath, subFileName)
        if os.path.isfile(subPath):
            subFile = {"type": "file", "name": subFileName}
            subFileList.append(subFile)
        else:
            subFolder = {"type": "folder", "name": subFileName, "subFiles": walkFolders(subPath)}
            subFileList.append(subFolder)
    return subFileList