问如何在C++中创建树？

EN

#include <vector>
#include <map>
#include <iostream>

using namespace std;

int main()
{
    map< int, vector<int> > adj_list;

    int edges;
    cin >> edges;
    for ( int i=0; i<edges; ++i ){
        int u, v;
        cin>>u>>v;
        adj_list[u].push_back(v);
        //adj_list[v].push_back(u); // uncomment this line if your graph is directed
    }

    for ( auto it = adj_list.begin(); it != adj_list.end(); ++it ){
        const auto& children = it->second;
        cout << "children of " << it->first << " is:" << endl;
        for ( int i=0; i < children.size(); ++i ){
            cout << children[i] << " ";
        }
        cout << endl;
    }
}

8
7 2
7 3
7 4
3 5
3 6
5 8
5 9
6 1

children of 3 is:
5 6 
children of 5 is:
8 9 
children of 6 is:
1 
children of 7 is:
2 3 4 

struct tree_node
{
    int value;
    std::vector<std::unique_ptr<tree_node>> children;
};