Title: Sum Root to Leaf Numbers Source: leetcode.com
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,
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1 2 3 |
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.
Python solution
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''' https://leetcode.com/problems/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 __init__(self): self.total = 0 def helper(self, root, num): num = num * 10 + root.val if not (root.left or root.right): self.total += num return if root.left: self.helper(root.left, num) if root.right: self.helper(root.right, num) def sumNumbers(self, root): """ :type root: TreeNode :rtype: int """ if not root: return 0 self.helper(root, 0) return self.total |
Given a binary tree, where every node value is a Digit from 1-9 .Find the sum of all the numbers which are formed from root to leaf paths.