Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number.
An example is the root-to-leaf path 1->2->3 which represents the number 123.
Find the total sum of all root-to-leaf numbers.
Note: A leaf is a node with no children.
Example:
Input: [1,2,3]
    1
   / \
  2   3
Output: 25
Explanation:
The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.
Therefore, sum = 12 + 13 = 25.
Example 2:
Input: [4,9,0,5,1]
    4
   / \
  9   0
 / \
5   1
Output: 1026
Explanation:
The root-to-leaf path 4->9->5 represents the number 495.
The root-to-leaf path 4->9->1 represents the number 491.
The root-to-leaf path 4->0 represents the number 40.
Therefore, sum = 495 + 491 + 40 = 1026.
# Definition for a binary tree node.
 # class TreeNode:
 #     def __init__(self, x):
 #         self.val = x
 #         self.left = None
 #         self.right = None
 from copy import deepcopy
 
 class Solution:
     def __init__(self):
         self.treeSum = 0
         
     def sumNumbers(self, root):
         """
         :type root: TreeNode
         :rtype: int
         """
         self.tree(root, [])
         return self.treeSum
     def tree(self, node, path):
         if not node:
             return False
         
         path.append(str(node.val))
         
         print(path, node.val)
         l = self.tree(node.left, copy.deepcopy(path))
         r = self.tree(node.right, copy.deepcopy(path))
         
         if not l and not r:
             self.treeSum += int(''.join(path))
         
         return True
# Definition for a binary tree node.
 # class TreeNode:
 #     def __init__(self, x):
 #         self.val = x
 #         self.left = None
 #         self.right = None
 from copy import deepcopy
 
 class Solution:
     def __init__(self):
         self.treeSum = 0
         
     def sumNumbers(self, root):
         """
         :type root: TreeNode
         :rtype: int
         """
         self.tree(root, [])
         return self.treeSum
     def tree(self, node, path):
         if not node:
             return False
         
         path.append(str(node.val))
         
         print(path, node.val)
         l = self.tree(node.left, copy.deepcopy(path))
         r = self.tree(node.right, copy.deepcopy(path))
         
         if not l and not r:
             self.treeSum += int(''.join(path))
         
         return True