#338 · #146 · LRU Cache(LRU 缓存)

Design a Least Recently Used (LRU) cache with a fixed capacity. Implement get(key) returning the value or -1, and put(key, value). Both must run in O(1) average time. When the capacity is exceeded, evict the least recently used key. Constraints: 1 <= capacity <= 3000; at most 2 * 10^5 calls.