Create 一个php算法的实现.php

http://www.dewen.org/q/6868/%E8%AF%B7%E6%95%99%E4%B8%80%E4%B8%AAphp%E7%AE%97%E6%B3%95%E7%9A%84%E5%AE%9E%E7%8E%B0