#include <iostream>

using namespace std;

class Set {

public:

    struct Node {
        int value;
        Node* left;
        Node* right;
        Node* parent;
    };

    Set() : root_(nullptr), size_(0) {}

    void insert(const int& val) {
        if (root_ == nullptr) {
            root_ = new Node{ val, nullptr, nullptr, nullptr };
            size_++;
            return;
        }
        Node* parent = nullptr;
        Node* node = root_;
        while (node != nullptr && node->value != val) {
            parent = node;
            node = node->value > val ? node->left : node->right;
        }
        if (node == nullptr) {
            node = new Node{ val, nullptr, nullptr, parent };
            parent->value > val ? parent->left = node : parent->right = node;
            size_++;
        }
    }

    void print() {
        print(root_);
        cout << endl;
    }

private:

    void print(Node* node) {
        if (node != nullptr) {
            print(node->left);
            cout << node->value << " ";
            print(node->right);
        }
    }

    Node* root_;
    int size_;
};


int main() {

    int arr[]{ 45,30,50,27,39,90,15,70,103 };

    Set st;

    for (int i = 0; i < 9; i++) {
        st.insert(arr[i]);
    }

    st.print();
}