leetcode 113 路径总和Ⅱ

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    vector<vector<int>> pathSum(TreeNode* root, int targetSum) {
        int sum=0;
        vector<vector<int>> res;   //存储最终结果
        vector<int> temp; //存储临时结果
        DFS(root,targetSum,sum,res,temp);
        return res;
    }
    void DFS(TreeNode* root,int targetSum,int sum,vector<vector<int>>& res,vector<int>& temp)
    {
        if(!root)
        {
            return;
        }
        if(!root->left && !root->right) //叶节点判断是否等值
        {
            sum+=root->val;
            if(sum==targetSum)
            {
                temp.push_back(root->val);
                res.push_back(temp);
                int value=temp[temp.size()-1];//移除该结果，返回上一层
                sum-=value;
                temp.pop_back();
                return;
            }
            sum-=root->val;
            return;
        }
        sum+=root->val;
        temp.push_back(root->val);
        DFS(root->left,targetSum,sum,res,temp);
        DFS(root->right,targetSum,sum,res,temp);
        sum-=root->val;
        temp.pop_back();//返回上一层
    }
};