C++ 代码

/**
 * 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>> res;
    vector<int> temp;
    vector<vector<int>> findPath(TreeNode* root, int sum) {
        if(root == NULL) return res;
        dfs(root,sum);
        return res;
    }
    void dfs(TreeNode * r, int sum){
        if(r->left == NULL && r->right == NULL){
            sum -= r->val;
            temp.push_back(r->val);
            if(sum == 0){
                res.push_back(temp);
            }
            //回溯
            temp.pop_back();
            return ;
        } 
        //非叶子节点
        sum -= r->val;
        temp.push_back(r->val);
        if(r->left) dfs(r->left,sum);
        if(r->right) dfs(r->right,sum);
        temp.pop_back();
        return ;
    }
};