From 629c6a367cd609001c6e743eca2a7094b5825cfd Mon Sep 17 00:00:00 2001
From: Beena P Jha <jhabeena95@gmail.com>
Date: Tue, 29 Oct 2019 21:02:16 +0530
Subject: [PATCH] Create Tree traversal - Preorder

---
 Tree traversal - Preorder | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 Tree traversal - Preorder

diff --git a/Tree traversal - Preorder b/Tree traversal - Preorder
new file mode 100644
index 0000000..fcb5292
--- /dev/null
+++ b/Tree traversal - Preorder	
@@ -0,0 +1,29 @@
+Tree Traversal - Preorder:
+
+###Iteration###
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution:
+    def preorderTraversal(self, root: TreeNode) -> List[int]:
+        res,stack = [],[root]
+        while stack:
+            cur = stack.pop()
+            if cur:
+                res.append(cur.val)
+                stack.append(cur.right)
+                stack.append(cur.left)
+        return res
+        
+###Recursion###:
+
+class Solution:
+    def preorderTraversal(self, root: TreeNode) -> List[int]:
+        res =[]
+        if root:
+            res += [root.val]+self.preorderTraversal(root.left)+ self.preorderTraversal(root.right)
+        return res