feat: 构造二叉树专题

Author: lucifer

README.md

@@ -280,6 +280,7 @@ leetcode 题解，记录自己的 leetcode 解题之路。
 - [字符串问题](./thinkings/string-problems.md)
 - [前缀树专题](./thinkings/trie.md) 🆕
 - [《日程安排》专题](https://lucifer.ren/blog/2020/02/03/leetcode-%E6%88%91%E7%9A%84%E6%97%A5%E7%A8%8B%E5%AE%89%E6%8E%92%E8%A1%A8%E7%B3%BB%E5%88%97/) 🆕
+- [《构造二叉树》专题](https://lucifer.ren/blog/2020/02/08/%E6%9E%84%E9%80%A0%E4%BA%8C%E5%8F%89%E6%A0%91%E4%B8%93%E9%A2%98/) 🆕
 
 ### anki 卡片