Design and implement a data structure for Least Recently Used (LRU) cache that supports the operations get and put. get(key) - Get the value (will always be positive) of the key if the key exists in the cache. Otherwise return -1. put(key, value) - Set or insert the value if the key is not already present. When the cache reaches its capacity, it should invalidate the least recently used item before inserting a new item. Could you do both operations in O(1) complexity?