leetcode129

 1 class Solution:
 2     def __init__(self):
 3         self.lists = []
 4         
 5     def preOrder(self,root,path):
 6         if root != None:
 7             path.append(str(root.val))
 8             if root.left != None:
 9                 self.preOrder(root.left,path)
10             if root.right != None:
11                 self.preOrder(root.right,path)
12             
13             if root.left == None and root.right == None:
14                 self.lists.append(path[:])
15             path.pop(-1)
16         
17     def sumNumbers(self, root: TreeNode) -> int:
18         if root == None:
19             return 0
20         else:
21             self.preOrder(root,[])
22             sums = 0
23             for li in self.lists:
24                 s = ''.join(li)
25                 n = int(s)
26                 sums += n
27             return sums