/**
 * 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<int> path;
    vector<vector<int>> res;
    vector<vector<int>> findPath(TreeNode* root, int sum) {
        if(root==NULL) return res;
        path.push_back(root->val);
        //为叶子节点
        if(root->left==NULL&&root->right==NULL)
            if(sum==root->val)
                //返回
                res.push_back(path);

        if(root->left!=NULL)
            findPath(root->left,sum-root->val);
        if(root->right!=NULL)
            findPath(root->right,sum-root->val);
        path.pop_back();

        return res;
    }
};