From a42c13186c812e12df791b937b125cc584e74ce2 Mon Sep 17 00:00:00 2001
From: bt3gl <138340846+bt3gl-cryptographer@users.noreply.github.com>
Date: Tue, 8 Aug 2023 14:21:03 -0700
Subject: [PATCH] Update bt_preorder.py

---
 trees/bt_preorder.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/trees/bt_preorder.py b/trees/bt_preorder.py
index 396e53b..352cc05 100644
--- a/trees/bt_preorder.py
+++ b/trees/bt_preorder.py
@@ -8,4 +8,20 @@ def preorder(root) -> list:
       return []
     
   return [root.val] + preorder(root.left) + preorder(root.right)
+    
         
+def preorder_iterative(root) -> list:
+        
+        result = []
+        stack = [root]
+        
+        while stack:
+            
+            node = stack.pop()
+            
+            if node:
+                result.append(node.val) 
+                stack.append(node.right) # not the order 
+                stack.append(node.left)
+            
+        return result