项目有个脚本，操作【文件/文件夹】用的【cp/rm】命令（平时在Mac上使用），现在要在Windows上也能使用，便用Python重写了下，文件/文件夹操作这部分封装了几个函数，做个记录以备后查。...

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.

Given an integer, write a function to determine if it is a power of three.

Given a non-negative integer num, repeatedly add all its digits until the result has only one digit. For example: Given num = 38, the process is like: 3 + ...