leetcode @python 129. Sum Root to Leaf Numbers
2016-04-03 11:17
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题目链接
https://leetcode.com/problems/sum-root-to-leaf-numbers/题目原文
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.
题目大意
计算从根到叶节点的数的和解题思路
使用递归求解,使用字符串存储从根到叶节点的数,求和的时候在转成整数代码
# 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): ans = 0 def sumNumbers(self, root): """ :type root: TreeNode :rtype: int """ if root == None: return 0 return self.helper(root, "") def helper(self, root, num): if root == None: return None num += str(root.val) l = self.helper(root.left, num) r = self.helper(root.right, num) if not l and not r: self.ans += int(num) return self.ans
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