leetcode+找出所有的符合sum只的情况+回溯

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//找出所有的情况，因此需要回溯
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <cstring>
#include <string.h>
#include <algorithm>
#include <vector>
#include <numeric>
#include <limits>
#include <math.h>
#include <queue>
using namespace std;
struct TreeNode {
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};
class Solution {
public:
    void dfs(TreeNode* root, int rest, vector<int>& path, vector<vector<int>>& res)
    {
        if(root==NULL) return;
        path.push_back(root->val);
        rest -= root->val;
        if(root->left==NULL && root->right==NULL){
            if(rest==0){
                res.push_back(path);
            }
        }
        else{
            if(root->left)
                dfs(root->left, rest, path, res);
            if(root->right)
                dfs(root->right, rest, path, res);
        }
        path.pop_back();
    }
    vector<vector<int>> pathSum(TreeNode* root, int sum) {
        vector<vector<int>> res;
        vector<int> path;
        dfs(root, sum, path, res);
        return res;
    }
};
int main()
{
    
    return 0;
}