LRU Cache

Implement an LRUCache class. LRU means least recently used.

When the cache exceeds its capacity, it should evict the least recently used key.

API

const cache = new LRUCache(2);
cache.set('a', 1);
cache.set('b', 2);
cache.get('a'); // 1, now a is most recent
cache.set('c', 3); // evicts b

Requirements

• get(key) returns the value or -1 when missing.
• set(key, value) inserts or updates a key.
• Both get and set should update recency.
• Evict the least recently used key when size exceeds capacity.
• Use O(1) average operations.