LRU Cache

Design a data structure that follows the constraints of a **Least Recently Used (LRU) cache**. The cache supports two operations: - `get(key)`: Return the value of `key` if it exists, otherwise return `-1`. - `put(key, value)`: Update the value of `key` if it exists. Otherwise, add the (key, value) pair to the cache. If inserting causes the cache to exceed its capacity, evict the **least recently used** key. Both operations must run in **O(1) average time**. **For the auto-grader:** implement a single function `lruCacheOps(capacity, operations)` that returns the result of each operation in order. Each operation is one of: - `["put", key, value]` → returns `null` (use `null` in JavaScript / `None` in Python). - `["get", key]` → returns the value or `-1`.