class Tree {

private:

// class TNode is private to the Tree class.
// nobody outside this class needs to know what nodes look like.
class TNode {
public: // a very open class...

  int data;  // int to keep life simple
  // . . .  other data could be added here if desired
  TNode *left, *right;

  TNode (int data, TNode *left, TNode *right) {
    TNode::data = data; TNode::left = left; TNode::right = right;
  }

};

TNode *root;  // root pointer
int size; // number of values in the tree

// deletes all of the nodes in a specified subtree
void purge (TNode* subroot);

// displays a subtree graphically using specified prefix strings
void subDisplay (String2002 leftPreString, String2002 midPreString,
                         String2002 rightPreString, TNode *subRoot);


public:

// simple methods are often implemented directly in the header file.
// this goes somewhat against the principle of "hiding" as many implementation
// details as possible in the header file, but does keep things simpler.
Tree () { // default constructor
  root = NULL; size = 0;
}

~Tree();  // destructor

// returns true if insertion successful (data does not already exist)
// and false otherwise.
bool insert (int data);

// returns true if deletion successful (data existed in tree)
// and false otherwise.
bool remove (int data);

// outputs tree graphically to "cout"
void display ();

// performs an LL rotation at the node containing the specified data value.
// returns true if the rotation was successfully performed and false otherwise
// (value not in tree or the node lacks a left child).
bool rotateLL (int data);

// performs an RR rotation at the node containing the specified data value.
// returns true if the rotation was successfully performed and false otherwise
// (value not in tree or the node lacks a right child).
bool rotateRR (int data);

// returns the height of the tree and sets "isBalanced" to true or
// false depending upon whether tree is balanced.
int height (bool &isBalanced);

};