What is an LRU Cache and how is it implemented?

What is an LRU Cache and how is it implemented?

An LRU (Least Recently Used) Cache is a data structure that stores a limited number of items and evicts the least recently used item when it reaches its capacity. It is commonly implemented using a combination of a hash map and a doubly linked list.

Can you explain how the hash map and doubly linked list work together?

Sure! The hash map allows for O(1) access time to cache items, while the doubly linked list maintains the order of usage. When an item is accessed, it is moved to the front of the list, and when the cache exceeds its limit, the item at the back of the list (the least recently used) is removed.

What are some common use cases for an LRU Cache?

Common use cases include caching database query results, web page data, and session information in web applications to improve performance.

Are there any drawbacks to using an LRU Cache?

Yes, the main drawbacks include increased memory usage for the data structure and potential overhead in maintaining the order of items, especially in high-frequency access scenarios.