6/22/2017 - 2:39 PM

129. Sum Root to Leaf Numbers

1. Sum Root to Leaf Numbers
``````# 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
"""
self.total = 0
self.DFS(root, 0)
return self.total
def DFS(self, node, curSum):
if node == None:
return
curSum = curSum*10 + node.val
if node.left == None and node.right == None:
self.total += curSum
if node.left:
self.DFS(node.left, curSum)
if node.right:
self.DFS(node.right, curSum)``````

https://leetcode.com/problems/sum-root-to-leaf-numbers/#/description

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`.