leetcode 113 path Sum II 路径和

递归先序遍历+vector<int>容器记录路径

 /**
  * 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();
     }
 };