Leetcode 129 Sum Root to Leaf Numbers

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

.

class Solution(object):
def sumNumbers(self, root):
return self.sn(0,root)

def sn(self,num,root):
if not root:
return 0
num = num*10 + root.val
if not root.left and not root.right:
return num
return self.sn(num,root.left) + self.sn(num,root.right)