题目
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.
解题思路
递归向下传递当前路径的数，如果是叶节点，返回这个数，否则返回两个子树和
代码
class Solution:
def sumNumbers(self, root: TreeNode) -> int:
def find(root, n):
if root is None:
return 0
cur = n * 10 + root.val
if root.left is None and root.right is None:
return cur
return find(root.left, cur) + find(root.right, cur)
return find(root, 0)
