sds:
https://blog.youkuaiyun.com/yellowriver007/article/details/79020923
zi[plist:(包含Redis set的并、交、差算法的复杂度)
https://blog.youkuaiyun.com/yellowriver007/article/details/79021049
skiplist
https://blog.youkuaiyun.com/yellowriver007/article/details/79021103