LeetCode: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. 

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     int sumNumbers(TreeNode* root) {
13              
14             int sum=0;
15             return dfs(root,sum);
16         
17     }
18     
19     int  dfs(TreeNode *root,int sum)
20     {
21         
22         if(root==NULL) return 0;
23         if(!root->left&&!root->right)
24           return sum*10+root->val;
25          
26         return dfs(root->left,sum*10+root->val)+dfs(root->right,sum*10+root->val);
27     }
28 };

 

posted @ 2015-09-06 19:51  尾巴草  阅读(130)  评论(0)  编辑  收藏  举报