利用一个递归算法，对用户自行的输入的数据进行加密，并且可以对加密的数据进行反向解码。-via a recursive algorithm, the program can encrypt the data the user input, and can encrypt data on the reverse decoding.

The greatest common divisor of integers x and y is the largest integer that evenly divides both x and y. Write a recursive function gcd that returns the greatest common divisor of x and y, define recursively as follows. It y is equal to 0, then gcd(x

B编码C++方案，用递归的方式解决，实现编码和解码-B coding C++ programs, using a recursive solution to achieve encoding and decoding