refactor 145

fishercoder1534 · fishercoder1534 · commit 04108bf7bec4 · 2021-09-23T09:50:59.000-07:00
diff --git a/README.md b/README.md
@@ -1079,7 +1079,7 @@ _If you like this project, please leave me a star._ &#9733;
 |149|[Max Points on a Line](https://leetcode.com/problems/max-points-on-a-line/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_149.java)| |Hard|
 |147|[Insertion Sort List](https://leetcode.com/problems/insertion-sort-list/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_147.java) ||Medium| Linked List
 |146|[LRU Cache](https://leetcode.com/problems/lru-cache/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_146.java)|  |Hard| Doubly Linked List, LinkedHashMap
-|145|[Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_145.java)|[:tv:](https://youtu.be/B6XTLPpsW7k) |Hard| Binary Tree
+|145|[Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_145.java)|[:tv:](https://youtu.be/B6XTLPpsW7k) |Easy| Binary Tree
 |144|[Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_144.java)|[:tv:](https://youtu.be/367McfIeBDM) and [:tv:](https://youtu.be/vMHaqhiTn7Y)|Medium| Binary Tree
 |143|[Reorder List](https://leetcode.com/problems/reorder-list/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_143.java)|  |Medium|
 |142|[Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_142.java)|  |Medium| Linked List
