Create trie_preorder.py

tries/trie_preorder.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# author: bt3gl
+
+
+def preorder(root: 'Node'):
+        
+        if root is None:
+            return []
+        
+        stack, result = [root, ], []
+
+        while stack:
+            node = stack.pop()
+            result.append(node.val)
+            stack.extend(node.children[::-1])
+            
+        return result