In LRU Cache, after moving a node in the list to the front, it updated `cacheMap[key]` to `cacheList.begin()`. But I don't think the iterator to the node will be changed after splicing.
In LRU Cache, after moving a node in the list to the front, it updated
cacheMap[key]tocacheList.begin().But I don't think the iterator to the node will be changed after splicing.