N-ary tree postorder traversal

Link: https://leetcode.com/problems/n-ary-tree-postorder-traversal/

Solution:

Topics: DFS

Intuition
Trivial little problem. Just do a DFS and append the parent node value to the result after all children have been visited. Postorder is typically how DP problems are structured.

Implementation

def post_order(root):
	res = []
	def dfs(node):
		if node is None:
			return
		for child in node.children:
			dfs(child)
		res.append(node.val)
	dfs(root)
	return res
 
#time: o(n)
#memory: o(n)

Review 1
Too easy. Remember that post-order is after the recursion (children added before parents).

review