# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def sumNumbers(self, root: TreeNode) -> int:
res = 0
def dfs(node, path):
if node is None:
return
path.append(node.val)
if node.left is None and node.right is None:
nonlocal res
for i, num in enumerate(path[::-1]):
res += num * 10 ** i
else:
dfs(node.left, path)
dfs(node.right, path)
path.pop()
dfs(root, [])
return res