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,0,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();
    }
};