[LeetCode]Sum Root to Leaf Numbers

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.

递归深搜，一类题。

 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     void dfs(TreeNode* root,int num,int& result)
13     {
14         num=num*10+root->val;
15         if(root->left==NULL && root->right==NULL)
16         {
17             result+=num;
18             return;
19         }
20         if(root->left) dfs(root->left,num,result);
21         if(root->right) dfs(root->right,num,result);
22     }
23     int sumNumbers(TreeNode* root) {
24         if(!root) return 0;
25         int num=0,result=0;
26         dfs(root,num,result);
27         return result;
28     }
29 };