struct node{
    int val;
    node* left;
    node* right;
};
//Initialize:
node* root = new node;
root->val = 7;
root->left = NULL;
root->right = NULL;

int* n = new(6);

struct node{
    int val;
    node* left;
    node* right;
    node(int);
};

node::node(int _v){
    this->val = _v;
    this->left = this->right = nullptr;
}

node *root = new node(6); // Works as you want