Implement LRU Cache

Design and implement a data structure for LRU (Least Recently Used) cache. It should support the following 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. Implement the LRUCache class with optimal time complexity O(1). Input: 2 put 1 1 put 2 2 get 1 put 3 3 get 2 put 4 4 get 1 get 3 get 4 Output: 1 -1 -1 3 4 Example Input 2 put 1 1 put 2 2 get 1 put 3 3 get 2 put 4 4 get 1 get 3 get 4