My solution for 145

Author: jeremymanning

problems/145/jeremymanning.md

@@ -1,11 +1,36 @@
 # [Problem 145: Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal/description/?envType=daily-question)
 
 ## Initial thoughts (stream-of-consciousness)
+- A nice easy one today!  This is just a depth-first search
 
 ## Refining the problem, round 2 thoughts
+- Nothing too tricky here.  The order should be "left, right, root"
+- I think we can just return the visited notes in reverse order
 
 ## Attempted solution(s)
 ```python
-class Solution:  # paste your code here!
-    ...
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def postorderTraversal(self, root: Optional[TreeNode]) -> List[int]:
+        vals = []
+        stack = [root]
+        while stack:
+            node = stack.pop()
+            if node is not None:
+                vals.append(node.val)            
+                stack.extend([node.left, node.right])
+        return vals[::-1]
 ```
+- Given test cases pass
+- New test case:
+    - `root = [1,null,2,3, 4, 5, 6, 7, null, 8, null, 9, 10, -100, -100]`: pass
+- Let's submit...
+
+![Screenshot 2024-08-24 at 8 59 51 PM](https://github.com/user-attachments/assets/ace94bdb-eab7-409d-a465-469f71e73edb)
+
+- Solved!