# # 【LeetCode】129. Sum Root to Leaf Numbers 解题报告（Python）

## # 题目描述：

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.

``````For example,

1
/ \
2   3
The root-to-leaf path 1->2 represents the number 12.
The root-to-leaf path 1->3 represents the number 13.

Return the sum = 12 + 13 = 25.
``````

## # 解题方法

``````# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
def sumNumbers(self, root):
"""
:type root: TreeNode
:rtype: int
"""
if root == None:
return 0
res = [0]
self.dfs(root, res, root.val)
return res[0]

def dfs(self, root, res, path):
if root.left == None and root.right == None:
res[0] += path
if root.left != None:
self.dfs(root.left, res, path * 10 + root.left.val)
if root.right != None:
self.dfs(root.right, res, path * 10 + root.right.val)
``````

2018 年 2 月 25 日