Default to HashMap / HashSet. Switch to: LinkedHashMap when output order should match insertion order. (It can also be configured for access order, which turns it into a simple LRU cache, the eviction ...

This repo has various data structures and algorithms implementations and problems around that for preparing the coding interviews. 🚀 👨‍💻💻 🚩 ...

Java集合框架中，Map和Set是最常用的两类容器，而HashSet与HashMap更是面试与工程实践的高频主角。 很多人能背出“HashMap存键值对、HashSet存唯一元素”的表面区别，却未必理解其底层设计同源——HashSet内部其实就持有一个HashMap，元素被当作key存储，value统一为一个占位对象。