sum-root-to-leaf-numbers——dfs

Given a binary tree containing digits from0-9only, each root-to-leaf path could represent a number.

An example is the root-to-leaf path1->2->3which represents the number123.

Find the total sum of all root-to-leaf numbers.

For example,

    1
   / \
  2   3

The root-to-leaf path1->2represents the number12.
The root-to-leaf path1->3represents the number13.

Return the sum = 12 + 13 =25.

 /**
  * Definition for binary tree
  * struct TreeNode {
  *     int val;
  *     TreeNode *left;
  *     TreeNode *right;
  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
  * };
  */
 class Solution {
 public:
     int sumNumbers(TreeNode *root) {
         if(root==NULL)
             return ;
         res=;
         dfs(root,);
         return res;
     }
     void dfs(TreeNode *root,int num){
         if(root!=NULL){
             num=num*+root->val;
         }
         if(root->left==NULL&&root->right==NULL){
             res+=num;
         }
         if(root->left!=NULL){
             dfs(root->left,num);
         }
         if(root->right!=NULL){
             dfs(root->right,num);
         }
     }
     int res;
 };