C++两个vector对象拼接方式

class Solution {
public:
    vector<vector<int>> subsets(vector<int>& nums) {
       
        vector<vector<int>> res({100});
        for (int n : nums) {
            vector<vector<int>> temp;
            for (auto r : res) {
                r.push_back(n);
                temp.push_back(r);
            }
            res.insert(res.end(), temp.begin(), temp.end());//从end()位置开始，将后面的vector拼接在后面（不包括temp.end()）。
        }
        return res;
    }
};

#include<iOStream>
#include<algorithm>
#include <vector>
using namespace std;
int main()
{
  vector<int> v1,v2;
  int num1,num2;
  cin>>num1;
  while (num1!=-1)
  {
    v1.push_back(num1);
    cin>>num1;
  }
  cin>>num2;
  while(num2!=-1)
  {
    v2.push_back(num2);
    cin>>num2;
  }
  vector<int> v3;
  v3.resize(v1.size()+v2.size());
  merge(v1.begin(), v1.end(), v2.begin(), v2.end(), v3.begin());
  sort(v3.begin(),v3.end());
  
  for(int i = 0;i<v3.size()-1;i++){
      cout<<v3[i]<<" ";
  }
  cout<<v3[v3.size()-1];
}