| 25 | insert(Tree, element) |
| 26 | return Tree |
| 27 | class Solution(object): |
| 28 | def preorderTraversal(self, root): |
| 29 | res = [] |
| 30 | st = [] |
| 31 | node = root |
| 32 | while node or st: |
| 33 | while node: |
| 34 | if node.data != None: |
| 35 | res.append(node.data) |
| 36 | st.append(node) |
| 37 | node = node.left |
| 38 | temp = st[-1] |
| 39 | st.pop() |
| 40 | if temp.right: |
| 41 | node = temp.right |
| 42 | return res |
| 43 | ob1 = Solution() |
| 44 | head = make_tree([3,9,20,None,None,15,7]) |
| 45 | print(ob1.preorderTraversal(head)) |