【题目描述】LFU (Least Frequently Used) is a famous cache eviction algorithm.For a cache with capacity k,
LRU Chains(or LRU lists)有它们相关的算法在过去已经修改过多次。尽管算法已经修改过，但LRU chain的功能仍然相同:为了帮助被频繁访问的buffer内置在cache中和帮助
