feat: update

2024/05/cpp_hashmap.md

@@ -0,0 +1,21 @@
+[Code](https://github.com/cs-learning-every-day/CS106L/tree/main/cs106L-assignment2)
+
+主要是const和template的使用结合。
+
+const函数都去直接掉用非const函数  
+
+```sh
+template <typename K, typename M, typename H>
+typename HashMap<K, M, H>::const_iterator HashMap<K, M, H>::begin() const {
+  // This is called the static_cast/const_cast trick, which allows us to reuse
+  // the non-const version of find to implement the const version.
+  // The idea is to cast this so it's pointing to a non-const HashMap, which
+  // calls the overload above (and prevent infinite recursion).
+  // Also note that we are calling the conversion operator in the iterator
+  // class!
+  return static_cast<const_iterator>(
+      const_cast<HashMap<K, M, H>*>(this)->begin());
+}
+```
+
+底层就是一个bucket array(hash索引), bucket是一个链表存储索引冲突的节点。

README.md

@@ -4,6 +4,7 @@ The best thing to do is have fun.
 - [Hobby Projects](/hobby_projects.md)
 - [Kata](/kata.md)
 - **2024-05**
+  - [怎么实现一个HashMap STL-compliant, industrial strength, robust, and blazingly fast data structure](/2024/05/cpp_hashmap.md)
   - [RC-EaseProbe 一个优雅的状态检测工具，支持多种协议和通知平台](/2024/05/rc_easeprobe.md)
   - [从一个Wiki地址如何一步一步的到另一个Wiki地址](/2024/05/wiki_start_to_wiki_end.md)
   - [如何手搓一个 CPU？](/2024/05/cs61cpu.md)