（1）FIFO：First In First Out，先进先出 （2）LRU：Least Recently Used，最近最少使用 （3）LFU：Least Frequently Used，最不经常使用-（1）FIFO：First In First Out （2）LRU：Least Recently Used （3）LFU：Least Frequently Used

实现cache替换算法，思路是改进的LRU和LFU算法，在一定程度上提高了原来的LRU算法的命中率。-Achieve cache replacement algorithm, idea is to improve the LRU and LFU algorithms, to a certain extent, the original LRU algorithm to improve the hit rate.