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.
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思路：
DFS。
c++ code:
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
int sumNumbers(TreeNode* root) {
return sumNumbers(root, 0);
}
// 自定义函数
int sumNumbers(TreeNode* root, int sum) {
if(!root) return 0;
int tmp = sum * 10 + root->val;
if(!root->left && !root->right) return tmp;
return sumNumbers(root->left, tmp) + sumNumbers(root->right, tmp);
}
};LeetCode:Sum Root to Leaf Numbers
原文：http://blog.csdn.net/itismelzp/article/details/51636419