TikTok OA 面试真题解析：Cache Eviction Policies | LRU / FIFO 缓存策略

Implement the Least Recently Used (LRU) and First In First Out (FIFO) cache eviction policies, respectively.

Pick ONE OR MORE options.

// LRU cache = LinkedHashMap(maxEntries)
Function put(key, value)
    if cache is full
        remove the least recently accessed entry from cache
    add the new entry to cache

// FIFO cache = Queue(maxEntries)
Function put(key, value)
    if cache is full
        remove the oldest entry from cache
    add the new entry to cache

这道题考察缓存淘汰策略的基本理解。LRU（Least Recently Used）应使用能够维护访问顺序的数据结构，例如 LinkedHashMap，当缓存满时删除“最近最少使用”的条目；而 FIFO（First In First Out）则应使用队列，缓存满时删除最早进入的条目。题目的关键是区分“按最近访问时间淘汰”和“按进入顺序淘汰”，两者在实现思路和适用场景上都不同。