Binary Tree Preorder Traversal

preorderTraversal.py

@@ -0,0 +1,26 @@
+# Definition for a  binary tree node
+# class TreeNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution:
+    # @param root, a tree node
+    # @return a list of integers
+    def preorderTraversal(self, root):
+        ll =[]
+        self.preOrder(root, ll)
+        return ll
+
+    def preOrder(self, root, ll):
+        if not root:
+            return ll
+        ll.append(root.val)
+        self.preOrder(root.left,ll)
+        self.preOrder(root.right,ll)
+        return ll
+
+
+
+