题目来源：https://leetcode.cn/problems/path-sum-ii/description/

 

C++题解：采用递归法，前序遍历，遍历每个叶子节点，路径和满足条件则将该路径保存下来。

class Solution {
public:
    void getlujing(TreeNode* node, int targetSum, int sumtmp, vector<int> lujing, vector<vector<int>>& result) {
        sumtmp = sumtmp + node->val;
        lujing.push_back(node->val);
        if(node->left == nullptr && node->right == nullptr) {
            if(sumtmp == targetSum) result.push_back(lujing);
            return;
        }
        if(node->left) getlujing(node->left, targetSum, sumtmp, lujing, result);
        if(node->right) getlujing(node->right, targetSum, sumtmp, lujing, result);
    }
    vector<vector<int>> pathSum(TreeNode* root, int targetSum) {
        vector<vector<int>> result;
        vector<int> lujing;
        int sumtmp = 0;
        if(!root) return result;
        getlujing(root, targetSum, sumtmp, lujing, result);
        return result;
    }
};