Binary search tree in C++

#include <iostream>
#include <climits>
#include <algorithm>
using namespace std;

class Node {
private:
    int data;
    Node *left;
    Node *right;

    friend class Tree;
public:
    Node(int value): data(value), left(NULL), right(NULL) {}
};

class Tree {
private:
    Node *root;

    void preOrder(Node *root) {
        if (root == NULL) {
            return ;
        }
        cout << root->data << " ";
        preOrder(root->left);
        preOrder(root->right);
    }

    void inOrder(Node *root) {
        if (root == NULL) {
            return ;
        }
        inOrder(root->left);
        cout << root->data << " ";
        inOrder(root->right);
    }

    void postOrder(Node *root) {
        if (root == NULL) {
            return ;
        }
        postOrder(root->left);
        postOrder(root->right);
        cout << root->data << " ";
    }

    void insert(Node *root, int value) {
        if (value < root->data) {
            if (root->left == NULL) {
                root->left = new Node(value);
                return ;
            }
            insert(root->left, value);
            return ;
        }

        if (root->right == NULL) {
            root->right = new Node(value);
            return ;
        }
        insert(root->right, value);
    }

    int getHeight(Node *root) {
        if (root == NULL) {
            return 0;
        }
        return max(getHeight(root->left), getHeight(root->right)) + 1;
    }

    int getMax(Node *root) {
        if (root->right == NULL) {
            return root->data;
        }
        return getMax(root->right);
    }

public:
    Tree(): root(NULL) {}

    void preOrder() {
        preOrder(root);
    }

    void inOrder() {
        inOrder(root);
    }

    void postOrder() {
        postOrder(root);
    }

    void insert(int value) {
        if (root == NULL) {
            root = new Node(value);
            return ;
        }
        insert(root, value);
    }

    int getHeight() {
        return getHeight(root);
    }

    int getMax() {
        if (root == NULL) {
            return INT_MIN;
        }
        return getMax(root);
    }

};

int main() {
    int arr[10] = {5, 3, 7, 2, 8, 10, 9, 1, 4, 6};
    Tree tree;
    for (int i = 0; i < 10; ++i) {
        tree.insert(arr[i]);
    }
    tree.preOrder();
    cout << endl;
    tree.inOrder();
    cout << endl;
    tree.postOrder();
    cout << endl;
    cout << "Height = " << tree.getHeight() << endl;
    cout << "MAX = " << tree.getMax() << endl;

    return 0;
}