LRU

Subtitle / Summary LeetCode 146 is not a memorize-the-template problem. It is the core cache-design exercise: how to support fast lookup and fast recency updates at the same time. Reading time: 14-18 min Tags: Hot100, LRU, hash table, doubly linked list SEO keywords: LRU Cache, hash table + doubly linked list, O(1) get put, LeetCode 146, Hot100 Meta description: A derivation-first ACERS guide to LRU Cache using a hash table plus doubly linked list, with engineering scenarios, pitfalls, and runnable multi-language code. A - Algorithm (Problem and Algorithm) Problem Restatement Design a data structure LRUCache with: ...

Subtitle / Summary This is not a memorization question. It is core cache-engineering practice: satisfy fast lookup and least-recently-used eviction at the same time, both in constant average time. We derive the optimal structure from naive approaches and provide runnable implementations. Reading time: 14-18 min Tags: LRU, hash map, doubly linked list, system design SEO keywords: LRU Cache, LeetCode 146, hash map, doubly linked list, O(1) Meta description: Build an LRU cache with hash map + doubly linked list to achieve O(1) average get/put, with engineering use cases, pitfalls, and six-language implementations. A — Algorithm (Problem & Algorithm) Problem Restatement Design and implement LRUCache: ...