My solution to 590

Author: jeremymanning

problems/590/jeremymanning.md

@@ -1,11 +1,44 @@
 # [Problem 590: N-ary Tree Postorder Traversal](https://leetcode.com/problems/n-ary-tree-postorder-traversal/description/?envType=daily-question)
 
 ## Initial thoughts (stream-of-consciousness)
+- This problem is the same as yesterday's, but with N-ary trees instead of binary trees
+- We can solve it the same way:
+    - Execute a depth-first  search, saving values to a list as we visit each node
+    - Push the root, then the children (left to right) to the stack
+    - At the end, return the list of values in reverse order
 
 ## Refining the problem, round 2 thoughts
+- The problem description doesn't say if all children are guaranteed to be non-null if there's a least one other non-null child of the given node.  I guess we'll need to see what happens when we run the code.
 
 ## Attempted solution(s)
 ```python
-class Solution:  # paste your code here!
-    ...
+"""
+# Definition for a Node.
+class Node:
+    def __init__(self, val=None, children=None):
+        self.val = val
+        self.children = children
+"""
+
+class Solution:
+    def postorder(self, root: 'Node') -> List[int]:
+        vals = []
+        stack = [root]
+        while stack:
+            node = stack.pop()
+            if node is not None:
+                vals.append(node.val)            
+                if node.children is not None:
+                    for c in node.children:
+                        stack.append(c)
+        return vals[::-1]
 ```
+- Given test cases pass
+- Let's try some others:
+    - `root = []`: pass
+    - `root = [1, null, 2, 3, 4, 5, 6, 7, 8, null, 9, 10, 11, 12, null, 13, 14, 15, 16, 17, null, 18, 19, 20, null, null, 21, 22, 23, null, 24]`: pass
+- Ok; let's submit!
+
+![Screenshot 2024-08-25 at 10 25 02 PM](https://github.com/user-attachments/assets/b8800303-2301-45f7-bbdc-9ef418d6a659)
+
+Solved 🎉!