tree

#include <iostream>
#include <sstream>
#include <exception>
#include <cmath>
#include <unordered_set>
#include <vector>
#include <unordered_map>
#include <algorithm>
using namespace std;

struct node{
    int* parent;
    int* l;
    int* r;
    node* self;
    node() : parent(nullptr), l(nullptr), r(nullptr), self(this) {}
    node(int *p, int *L, int *R) : parent(p), l(L), r(R), self(this) {}
};

struct tree{
    vector <int> a = {1, 2, 3, 4, 5};


    node main_root;
    node create_subtree(int Li, int Ri) {
        /*Ri == Li + 2 - ok
        Ri == Li + 1
        Ri == Li*/
        node root();
        if (Li == Ri) {

        }

        root.self = &arr[len / 2];
        node left_root = create_subtree(0, len / 2 - 1);
        node right_root = create_subtree(len / 2 + 1, len - 1);
        root.l = left_root.self;
        root.r = right_root.self;
        return root;
    }
    void create(vector <int> arr) {
        a = arr;
        int len = a.size();
        create_subtree(0, len);
        return;
    }
    void output() {
        return;
    }
    void find_first(int*  v) {
        return;
    }
    void find_nex(int* v) {
        return;
    }
    void insert_after(int* v) { //а insert_defore надо?
        return;
    }
};

int main() {
    tree T;
    vector <int> a = {1, 2, 3, 4, 5};
    T()
}