/**

  * 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:

     vector<vector<int>> pathSum(TreeNode* root, int sum) {

         vector<int> out;

         vector<vector<int>> res;

         dfs(root,sum,,out,res);

         return res;

     }

     //还是递归先序遍历+vector<int>容器记录路径

     void dfs(TreeNode* node,int sum,int curSum,vector<int> &out,vector<vector<int>> &res){

         if(!node) return;

         curSum+=node->val;

         out.push_back(node->val);

         if(node->left==NULL&&node->right==NULL&&curSum==sum) res.push_back(out);

         dfs(node->left,sum,curSum,out,res);

         dfs(node->right,sum,curSum,out,res);

         out.pop_back();

     }

 };